ch-1material science of polymers for engineers
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7252019 CH-1Material Science of Polymers for Engineers
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Osswald Menges
Material Science of Polymers for Engineers
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 238
7252019 CH-1Material Science of Polymers for Engineers
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Material Science
of Polymersfor Engineers
Tim A Osswald
Georg Menges
Hanser Publishers Munich Hanser Publications Cincinnati
3rd Edition
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 438
Te Author
Pro Dr im A OsswaldUniversity o Wisconsin-Madison Polymer Processing Research GroupDepartment o Mechanical Engineering 1513 University Avenue Madison USA
Pro Dr-Ing Georg MengesAm Beulardstein 19 Aachen Germany
Distributed in North and South America byHanser Publications6915 Valley Avenue Cincinnati Ohio 45244-3029 USAFax (513) 527-8801Phone (513) 527-8977wwwhanserpublicationscom
Distributed in all other countries byCarl Hanser VerlagPostach 86 04 20 81631 Muumlnchen GermanyFax +49 (89) 98 48 09wwwhanserde
Te use o general descriptive names trademarks etc in this publication even i the ormer are not especiallyidentified is not to be taken as a sign that such names as understood by the rade Marks and Merchandise MarksAct may accordingly be used reely by anyoneWhile the advice and inormation in this book are believed to be true and accurate at the date o going to pressneither the authors nor the editors nor the publisher can accept any legal responsibility or any errors or omissionsthat may be made Te publisher makes no warranty express or implied with respect to the material containedherein
Library o Congress Cataloging-in-Publication Data
Osswald im A Material science o polymers or engineers im A Osswald Georg Menges -- 3rd edition pages cm Includes bibliographical reerences and indexes ISBN 978-1-56990-514-2 (hardcover) -- ISBN (invalid) 978-1-56990-524-1 (e-book) 1 Polymers 2 Plastics--Molding I Menges Georg 1923- II itle
P1120O848 2012 6689--dc23
2012019893
Bibliografische Inormation Der Deutschen BibliothekDie Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografiedetaillierte bibliografische Daten sind im Internet uumlber lthttpdnbd-nbdegt abrufar
ISBN 978-1-56990-514-2E-Book-ISBN 9781569905241
All rights reserved No part o this book may be reproduced or transmitted in any orm or by any meanselectronic or mechanical including photocopying or by any inormation storage and retrieval systemwithout permission in writing rom the publisher
copy Carl Hanser Verlag Munich 2010Production Management Steffen Joumlrg
Coverconcept Marc Muumlller-Bremer wwwrebrandingde MuumlnchenCoverdesign Stephan Roumlnigk ypeset printed and bound by Koumlsel KrugzellPrinted in Germany
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7252019 CH-1Material Science of Polymers for Engineers
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VI Preface to the First Edition
are grateul to Richard Theriault or prooreading the entire manuscript We also
thank the ollowing people who helped prooread or gave suggestions during the
preparation o the book Susanne Belovari Bruce A Davis Jeffrey Giacomin Paul J
Gramann Matthew Kaegebein Gwan-Wan Lai Maria del Pilar Noriega E Antoine C
Rios B Linards U Stradins and Ester M Sun Susanne Belovari and Andrea Jung-Mack are acknowledged or translating portions o Werkstoffkunde Kunststoffe rom
German to English We also thank Tara Ruggiero or preparing the camera-ready
manuscript Many o the figures were taken rom class notes o the mechanical engi-
neering senior elective course Engineering Design with Polymers Special thanks
are offered to Lynda Litzkow Philipp Ehrenstein and Bryan Hutchinson or the
superb job o drawing those figures Matthias Mahlke o Bayer AG in Leverkusen
Germany Laura Dietsche Joseph Dooley and Kevin Hughes o Dow Chemical in Mid-
land Michigan and Mauricio DeGrei and Juan Diego Sierra o the ICIPC in Medelliacuten
Colombia are acknowledged or some o the figures Thanks are due to Marcia
Sanders or copy editing the final manuscript We are grateul to Wolgang Glenz
Martha Kuumlrzl Ed Immergut and Carol Radtke o Hanser Publishers or their support
throughout the development o this book Above all the authors thank their wives
or their patience
Summer 1995
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
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The first edition o this book was adopted by several universities in North and
South America Europe and Asia as a textbook to introduce engineering students
to the materials science o polymers The book was also translated into Japanese in
1998 Korean in 1999 and Spanish in 2008 The proessors who taught with thefirst and second editions as well as their students liked the unified approach we
took The changes and additions that were introduced in this edition are based on
suggestions rom these proessors and their students as well as rom our own
experience using it as a class textbook
Afer two revisions and two decades o teaching it has become clear that sustaina-
bility and profits are important when dealing with polymeric materials Thereore
the 4Prsquos o the first edition have expanded to the 6Prsquos in the third edition polymer
processing product perormace post-consumer lie and profit In the last 18
years this book has become a reerence or many practicing engineers most o
whom were introduced to the book as students The first and second editions were
praised because o the vast number o graphs and data that can be used as reer-
ences We have urther strengthened this attribute by expanding a comprehensive
table in the appendix that contains material property graphs or several polymers
Furthermore in this edition we added color to the figures and graphs making the
book more appealing to the reader
With this edition we owe our gratitude to Dr Christine Strohm or editing the book
and catching those small typos and inconsistencies in the text and equations Wethank Dr Nadine Warkotsch and Steffen Joerg o Hanser Publishers or their coop-
eration during the production o this book We are grateul to Luz Mayed D
Nouguez and Tobias Mattner or the superb job drawing the figures and to Tobias
Mattner or his suggestions on how to make many o the figures more understand-
able A special thanks to Katerina Saacutenchez or the graphs related to recycling o
plastics in Chapter 1 and to Nora Catalina Restrepo or generating the polymer
statistic graphs in Chapter 2 My graduate students Roberto Monroy Luisa Loacutepez
Tom Mulholland Jakob Onken Camilo Peacuterez Daniel Ramiacuterez Jochen Wellekoetter
and Yuxiao Zhang organized by William Aquite supplied extra problems and solu-
tions or the third edition thank you Special thanks to Diane or ndash as always ndash
serving as a sounding board and advisor during this project
Spring 2012
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
Preface to the
Third Edition
3
Z e i l e n
Uuml b e r s a t z
b i t t e
k uuml r z e n
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Contents
Preface to the First Edition V
Preface to the Third Edition VII
983089 Introduction 983091
983089983089 The 983094 Prsquos 983091
983089983090 General Information 983094
983089983091 Identification of Polymers 983089983091
983089983092 Sustainability ndash The 983094th P 983089983093
References 983090983088
983090 Historical Background 983090983089
983090983089 From Natural to Synthetic Rubber 983090983089
983090983090 Cellulose and the $983089983088983088983088983088 Idea 983090983095
983090983091 Galalith ndash The Milk Stone 983091983088
983090983092 Leo Baekeland and the Plastics Industry 983091983089
983090983093 Herman Mark and the American Polymer Education 983091983092
983090983094 Wallace Hume Carothers and Synthetic Polymers 983091983095
983090983095 Polyethylene ndash A Product of Brain and Brawn 983091983097
983090983096 The Super Fiber and the Woman Who Invented It 983092983090
983090983097 One Last Word ndash Plastics 983092983092
References 983092983095
983091 Structure of Polymers 983092983097
983091983089 Macromolecular Structure of Polymers 983092983097983091983090 Molecular Bonds and Inter-Molecular Attraction 983093983088
983091983091 Molecular Weight 983093983089
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
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Material Science
of Polymersfor Engineers
Tim A Osswald
Georg Menges
Hanser Publishers Munich Hanser Publications Cincinnati
3rd Edition
7252019 CH-1Material Science of Polymers for Engineers
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Te Author
Pro Dr im A OsswaldUniversity o Wisconsin-Madison Polymer Processing Research GroupDepartment o Mechanical Engineering 1513 University Avenue Madison USA
Pro Dr-Ing Georg MengesAm Beulardstein 19 Aachen Germany
Distributed in North and South America byHanser Publications6915 Valley Avenue Cincinnati Ohio 45244-3029 USAFax (513) 527-8801Phone (513) 527-8977wwwhanserpublicationscom
Distributed in all other countries byCarl Hanser VerlagPostach 86 04 20 81631 Muumlnchen GermanyFax +49 (89) 98 48 09wwwhanserde
Te use o general descriptive names trademarks etc in this publication even i the ormer are not especiallyidentified is not to be taken as a sign that such names as understood by the rade Marks and Merchandise MarksAct may accordingly be used reely by anyoneWhile the advice and inormation in this book are believed to be true and accurate at the date o going to pressneither the authors nor the editors nor the publisher can accept any legal responsibility or any errors or omissionsthat may be made Te publisher makes no warranty express or implied with respect to the material containedherein
Library o Congress Cataloging-in-Publication Data
Osswald im A Material science o polymers or engineers im A Osswald Georg Menges -- 3rd edition pages cm Includes bibliographical reerences and indexes ISBN 978-1-56990-514-2 (hardcover) -- ISBN (invalid) 978-1-56990-524-1 (e-book) 1 Polymers 2 Plastics--Molding I Menges Georg 1923- II itle
P1120O848 2012 6689--dc23
2012019893
Bibliografische Inormation Der Deutschen BibliothekDie Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografiedetaillierte bibliografische Daten sind im Internet uumlber lthttpdnbd-nbdegt abrufar
ISBN 978-1-56990-514-2E-Book-ISBN 9781569905241
All rights reserved No part o this book may be reproduced or transmitted in any orm or by any meanselectronic or mechanical including photocopying or by any inormation storage and retrieval systemwithout permission in writing rom the publisher
copy Carl Hanser Verlag Munich 2010Production Management Steffen Joumlrg
Coverconcept Marc Muumlller-Bremer wwwrebrandingde MuumlnchenCoverdesign Stephan Roumlnigk ypeset printed and bound by Koumlsel KrugzellPrinted in Germany
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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VI Preface to the First Edition
are grateul to Richard Theriault or prooreading the entire manuscript We also
thank the ollowing people who helped prooread or gave suggestions during the
preparation o the book Susanne Belovari Bruce A Davis Jeffrey Giacomin Paul J
Gramann Matthew Kaegebein Gwan-Wan Lai Maria del Pilar Noriega E Antoine C
Rios B Linards U Stradins and Ester M Sun Susanne Belovari and Andrea Jung-Mack are acknowledged or translating portions o Werkstoffkunde Kunststoffe rom
German to English We also thank Tara Ruggiero or preparing the camera-ready
manuscript Many o the figures were taken rom class notes o the mechanical engi-
neering senior elective course Engineering Design with Polymers Special thanks
are offered to Lynda Litzkow Philipp Ehrenstein and Bryan Hutchinson or the
superb job o drawing those figures Matthias Mahlke o Bayer AG in Leverkusen
Germany Laura Dietsche Joseph Dooley and Kevin Hughes o Dow Chemical in Mid-
land Michigan and Mauricio DeGrei and Juan Diego Sierra o the ICIPC in Medelliacuten
Colombia are acknowledged or some o the figures Thanks are due to Marcia
Sanders or copy editing the final manuscript We are grateul to Wolgang Glenz
Martha Kuumlrzl Ed Immergut and Carol Radtke o Hanser Publishers or their support
throughout the development o this book Above all the authors thank their wives
or their patience
Summer 1995
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
7252019 CH-1Material Science of Polymers for Engineers
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The first edition o this book was adopted by several universities in North and
South America Europe and Asia as a textbook to introduce engineering students
to the materials science o polymers The book was also translated into Japanese in
1998 Korean in 1999 and Spanish in 2008 The proessors who taught with thefirst and second editions as well as their students liked the unified approach we
took The changes and additions that were introduced in this edition are based on
suggestions rom these proessors and their students as well as rom our own
experience using it as a class textbook
Afer two revisions and two decades o teaching it has become clear that sustaina-
bility and profits are important when dealing with polymeric materials Thereore
the 4Prsquos o the first edition have expanded to the 6Prsquos in the third edition polymer
processing product perormace post-consumer lie and profit In the last 18
years this book has become a reerence or many practicing engineers most o
whom were introduced to the book as students The first and second editions were
praised because o the vast number o graphs and data that can be used as reer-
ences We have urther strengthened this attribute by expanding a comprehensive
table in the appendix that contains material property graphs or several polymers
Furthermore in this edition we added color to the figures and graphs making the
book more appealing to the reader
With this edition we owe our gratitude to Dr Christine Strohm or editing the book
and catching those small typos and inconsistencies in the text and equations Wethank Dr Nadine Warkotsch and Steffen Joerg o Hanser Publishers or their coop-
eration during the production o this book We are grateul to Luz Mayed D
Nouguez and Tobias Mattner or the superb job drawing the figures and to Tobias
Mattner or his suggestions on how to make many o the figures more understand-
able A special thanks to Katerina Saacutenchez or the graphs related to recycling o
plastics in Chapter 1 and to Nora Catalina Restrepo or generating the polymer
statistic graphs in Chapter 2 My graduate students Roberto Monroy Luisa Loacutepez
Tom Mulholland Jakob Onken Camilo Peacuterez Daniel Ramiacuterez Jochen Wellekoetter
and Yuxiao Zhang organized by William Aquite supplied extra problems and solu-
tions or the third edition thank you Special thanks to Diane or ndash as always ndash
serving as a sounding board and advisor during this project
Spring 2012
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
Preface to the
Third Edition
3
Z e i l e n
Uuml b e r s a t z
b i t t e
k uuml r z e n
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7252019 CH-1Material Science of Polymers for Engineers
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Contents
Preface to the First Edition V
Preface to the Third Edition VII
983089 Introduction 983091
983089983089 The 983094 Prsquos 983091
983089983090 General Information 983094
983089983091 Identification of Polymers 983089983091
983089983092 Sustainability ndash The 983094th P 983089983093
References 983090983088
983090 Historical Background 983090983089
983090983089 From Natural to Synthetic Rubber 983090983089
983090983090 Cellulose and the $983089983088983088983088983088 Idea 983090983095
983090983091 Galalith ndash The Milk Stone 983091983088
983090983092 Leo Baekeland and the Plastics Industry 983091983089
983090983093 Herman Mark and the American Polymer Education 983091983092
983090983094 Wallace Hume Carothers and Synthetic Polymers 983091983095
983090983095 Polyethylene ndash A Product of Brain and Brawn 983091983097
983090983096 The Super Fiber and the Woman Who Invented It 983092983090
983090983097 One Last Word ndash Plastics 983092983092
References 983092983095
983091 Structure of Polymers 983092983097
983091983089 Macromolecular Structure of Polymers 983092983097983091983090 Molecular Bonds and Inter-Molecular Attraction 983093983088
983091983091 Molecular Weight 983093983089
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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7252019 CH-1Material Science of Polymers for Engineers
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
7252019 CH-1Material Science of Polymers for Engineers
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 1538
983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 3: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/3.jpg)
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Material Science
of Polymersfor Engineers
Tim A Osswald
Georg Menges
Hanser Publishers Munich Hanser Publications Cincinnati
3rd Edition
7252019 CH-1Material Science of Polymers for Engineers
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Te Author
Pro Dr im A OsswaldUniversity o Wisconsin-Madison Polymer Processing Research GroupDepartment o Mechanical Engineering 1513 University Avenue Madison USA
Pro Dr-Ing Georg MengesAm Beulardstein 19 Aachen Germany
Distributed in North and South America byHanser Publications6915 Valley Avenue Cincinnati Ohio 45244-3029 USAFax (513) 527-8801Phone (513) 527-8977wwwhanserpublicationscom
Distributed in all other countries byCarl Hanser VerlagPostach 86 04 20 81631 Muumlnchen GermanyFax +49 (89) 98 48 09wwwhanserde
Te use o general descriptive names trademarks etc in this publication even i the ormer are not especiallyidentified is not to be taken as a sign that such names as understood by the rade Marks and Merchandise MarksAct may accordingly be used reely by anyoneWhile the advice and inormation in this book are believed to be true and accurate at the date o going to pressneither the authors nor the editors nor the publisher can accept any legal responsibility or any errors or omissionsthat may be made Te publisher makes no warranty express or implied with respect to the material containedherein
Library o Congress Cataloging-in-Publication Data
Osswald im A Material science o polymers or engineers im A Osswald Georg Menges -- 3rd edition pages cm Includes bibliographical reerences and indexes ISBN 978-1-56990-514-2 (hardcover) -- ISBN (invalid) 978-1-56990-524-1 (e-book) 1 Polymers 2 Plastics--Molding I Menges Georg 1923- II itle
P1120O848 2012 6689--dc23
2012019893
Bibliografische Inormation Der Deutschen BibliothekDie Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografiedetaillierte bibliografische Daten sind im Internet uumlber lthttpdnbd-nbdegt abrufar
ISBN 978-1-56990-514-2E-Book-ISBN 9781569905241
All rights reserved No part o this book may be reproduced or transmitted in any orm or by any meanselectronic or mechanical including photocopying or by any inormation storage and retrieval systemwithout permission in writing rom the publisher
copy Carl Hanser Verlag Munich 2010Production Management Steffen Joumlrg
Coverconcept Marc Muumlller-Bremer wwwrebrandingde MuumlnchenCoverdesign Stephan Roumlnigk ypeset printed and bound by Koumlsel KrugzellPrinted in Germany
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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VI Preface to the First Edition
are grateul to Richard Theriault or prooreading the entire manuscript We also
thank the ollowing people who helped prooread or gave suggestions during the
preparation o the book Susanne Belovari Bruce A Davis Jeffrey Giacomin Paul J
Gramann Matthew Kaegebein Gwan-Wan Lai Maria del Pilar Noriega E Antoine C
Rios B Linards U Stradins and Ester M Sun Susanne Belovari and Andrea Jung-Mack are acknowledged or translating portions o Werkstoffkunde Kunststoffe rom
German to English We also thank Tara Ruggiero or preparing the camera-ready
manuscript Many o the figures were taken rom class notes o the mechanical engi-
neering senior elective course Engineering Design with Polymers Special thanks
are offered to Lynda Litzkow Philipp Ehrenstein and Bryan Hutchinson or the
superb job o drawing those figures Matthias Mahlke o Bayer AG in Leverkusen
Germany Laura Dietsche Joseph Dooley and Kevin Hughes o Dow Chemical in Mid-
land Michigan and Mauricio DeGrei and Juan Diego Sierra o the ICIPC in Medelliacuten
Colombia are acknowledged or some o the figures Thanks are due to Marcia
Sanders or copy editing the final manuscript We are grateul to Wolgang Glenz
Martha Kuumlrzl Ed Immergut and Carol Radtke o Hanser Publishers or their support
throughout the development o this book Above all the authors thank their wives
or their patience
Summer 1995
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
7252019 CH-1Material Science of Polymers for Engineers
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The first edition o this book was adopted by several universities in North and
South America Europe and Asia as a textbook to introduce engineering students
to the materials science o polymers The book was also translated into Japanese in
1998 Korean in 1999 and Spanish in 2008 The proessors who taught with thefirst and second editions as well as their students liked the unified approach we
took The changes and additions that were introduced in this edition are based on
suggestions rom these proessors and their students as well as rom our own
experience using it as a class textbook
Afer two revisions and two decades o teaching it has become clear that sustaina-
bility and profits are important when dealing with polymeric materials Thereore
the 4Prsquos o the first edition have expanded to the 6Prsquos in the third edition polymer
processing product perormace post-consumer lie and profit In the last 18
years this book has become a reerence or many practicing engineers most o
whom were introduced to the book as students The first and second editions were
praised because o the vast number o graphs and data that can be used as reer-
ences We have urther strengthened this attribute by expanding a comprehensive
table in the appendix that contains material property graphs or several polymers
Furthermore in this edition we added color to the figures and graphs making the
book more appealing to the reader
With this edition we owe our gratitude to Dr Christine Strohm or editing the book
and catching those small typos and inconsistencies in the text and equations Wethank Dr Nadine Warkotsch and Steffen Joerg o Hanser Publishers or their coop-
eration during the production o this book We are grateul to Luz Mayed D
Nouguez and Tobias Mattner or the superb job drawing the figures and to Tobias
Mattner or his suggestions on how to make many o the figures more understand-
able A special thanks to Katerina Saacutenchez or the graphs related to recycling o
plastics in Chapter 1 and to Nora Catalina Restrepo or generating the polymer
statistic graphs in Chapter 2 My graduate students Roberto Monroy Luisa Loacutepez
Tom Mulholland Jakob Onken Camilo Peacuterez Daniel Ramiacuterez Jochen Wellekoetter
and Yuxiao Zhang organized by William Aquite supplied extra problems and solu-
tions or the third edition thank you Special thanks to Diane or ndash as always ndash
serving as a sounding board and advisor during this project
Spring 2012
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
Preface to the
Third Edition
3
Z e i l e n
Uuml b e r s a t z
b i t t e
k uuml r z e n
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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Contents
Preface to the First Edition V
Preface to the Third Edition VII
983089 Introduction 983091
983089983089 The 983094 Prsquos 983091
983089983090 General Information 983094
983089983091 Identification of Polymers 983089983091
983089983092 Sustainability ndash The 983094th P 983089983093
References 983090983088
983090 Historical Background 983090983089
983090983089 From Natural to Synthetic Rubber 983090983089
983090983090 Cellulose and the $983089983088983088983088983088 Idea 983090983095
983090983091 Galalith ndash The Milk Stone 983091983088
983090983092 Leo Baekeland and the Plastics Industry 983091983089
983090983093 Herman Mark and the American Polymer Education 983091983092
983090983094 Wallace Hume Carothers and Synthetic Polymers 983091983095
983090983095 Polyethylene ndash A Product of Brain and Brawn 983091983097
983090983096 The Super Fiber and the Woman Who Invented It 983092983090
983090983097 One Last Word ndash Plastics 983092983092
References 983092983095
983091 Structure of Polymers 983092983097
983091983089 Macromolecular Structure of Polymers 983092983097983091983090 Molecular Bonds and Inter-Molecular Attraction 983093983088
983091983091 Molecular Weight 983093983089
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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7252019 CH-1Material Science of Polymers for Engineers
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 4: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/4.jpg)
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Te Author
Pro Dr im A OsswaldUniversity o Wisconsin-Madison Polymer Processing Research GroupDepartment o Mechanical Engineering 1513 University Avenue Madison USA
Pro Dr-Ing Georg MengesAm Beulardstein 19 Aachen Germany
Distributed in North and South America byHanser Publications6915 Valley Avenue Cincinnati Ohio 45244-3029 USAFax (513) 527-8801Phone (513) 527-8977wwwhanserpublicationscom
Distributed in all other countries byCarl Hanser VerlagPostach 86 04 20 81631 Muumlnchen GermanyFax +49 (89) 98 48 09wwwhanserde
Te use o general descriptive names trademarks etc in this publication even i the ormer are not especiallyidentified is not to be taken as a sign that such names as understood by the rade Marks and Merchandise MarksAct may accordingly be used reely by anyoneWhile the advice and inormation in this book are believed to be true and accurate at the date o going to pressneither the authors nor the editors nor the publisher can accept any legal responsibility or any errors or omissionsthat may be made Te publisher makes no warranty express or implied with respect to the material containedherein
Library o Congress Cataloging-in-Publication Data
Osswald im A Material science o polymers or engineers im A Osswald Georg Menges -- 3rd edition pages cm Includes bibliographical reerences and indexes ISBN 978-1-56990-514-2 (hardcover) -- ISBN (invalid) 978-1-56990-524-1 (e-book) 1 Polymers 2 Plastics--Molding I Menges Georg 1923- II itle
P1120O848 2012 6689--dc23
2012019893
Bibliografische Inormation Der Deutschen BibliothekDie Deutsche Bibliothek verzeichnet diese Publikation in der Deutschen Nationalbibliografiedetaillierte bibliografische Daten sind im Internet uumlber lthttpdnbd-nbdegt abrufar
ISBN 978-1-56990-514-2E-Book-ISBN 9781569905241
All rights reserved No part o this book may be reproduced or transmitted in any orm or by any meanselectronic or mechanical including photocopying or by any inormation storage and retrieval systemwithout permission in writing rom the publisher
copy Carl Hanser Verlag Munich 2010Production Management Steffen Joumlrg
Coverconcept Marc Muumlller-Bremer wwwrebrandingde MuumlnchenCoverdesign Stephan Roumlnigk ypeset printed and bound by Koumlsel KrugzellPrinted in Germany
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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VI Preface to the First Edition
are grateul to Richard Theriault or prooreading the entire manuscript We also
thank the ollowing people who helped prooread or gave suggestions during the
preparation o the book Susanne Belovari Bruce A Davis Jeffrey Giacomin Paul J
Gramann Matthew Kaegebein Gwan-Wan Lai Maria del Pilar Noriega E Antoine C
Rios B Linards U Stradins and Ester M Sun Susanne Belovari and Andrea Jung-Mack are acknowledged or translating portions o Werkstoffkunde Kunststoffe rom
German to English We also thank Tara Ruggiero or preparing the camera-ready
manuscript Many o the figures were taken rom class notes o the mechanical engi-
neering senior elective course Engineering Design with Polymers Special thanks
are offered to Lynda Litzkow Philipp Ehrenstein and Bryan Hutchinson or the
superb job o drawing those figures Matthias Mahlke o Bayer AG in Leverkusen
Germany Laura Dietsche Joseph Dooley and Kevin Hughes o Dow Chemical in Mid-
land Michigan and Mauricio DeGrei and Juan Diego Sierra o the ICIPC in Medelliacuten
Colombia are acknowledged or some o the figures Thanks are due to Marcia
Sanders or copy editing the final manuscript We are grateul to Wolgang Glenz
Martha Kuumlrzl Ed Immergut and Carol Radtke o Hanser Publishers or their support
throughout the development o this book Above all the authors thank their wives
or their patience
Summer 1995
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
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The first edition o this book was adopted by several universities in North and
South America Europe and Asia as a textbook to introduce engineering students
to the materials science o polymers The book was also translated into Japanese in
1998 Korean in 1999 and Spanish in 2008 The proessors who taught with thefirst and second editions as well as their students liked the unified approach we
took The changes and additions that were introduced in this edition are based on
suggestions rom these proessors and their students as well as rom our own
experience using it as a class textbook
Afer two revisions and two decades o teaching it has become clear that sustaina-
bility and profits are important when dealing with polymeric materials Thereore
the 4Prsquos o the first edition have expanded to the 6Prsquos in the third edition polymer
processing product perormace post-consumer lie and profit In the last 18
years this book has become a reerence or many practicing engineers most o
whom were introduced to the book as students The first and second editions were
praised because o the vast number o graphs and data that can be used as reer-
ences We have urther strengthened this attribute by expanding a comprehensive
table in the appendix that contains material property graphs or several polymers
Furthermore in this edition we added color to the figures and graphs making the
book more appealing to the reader
With this edition we owe our gratitude to Dr Christine Strohm or editing the book
and catching those small typos and inconsistencies in the text and equations Wethank Dr Nadine Warkotsch and Steffen Joerg o Hanser Publishers or their coop-
eration during the production o this book We are grateul to Luz Mayed D
Nouguez and Tobias Mattner or the superb job drawing the figures and to Tobias
Mattner or his suggestions on how to make many o the figures more understand-
able A special thanks to Katerina Saacutenchez or the graphs related to recycling o
plastics in Chapter 1 and to Nora Catalina Restrepo or generating the polymer
statistic graphs in Chapter 2 My graduate students Roberto Monroy Luisa Loacutepez
Tom Mulholland Jakob Onken Camilo Peacuterez Daniel Ramiacuterez Jochen Wellekoetter
and Yuxiao Zhang organized by William Aquite supplied extra problems and solu-
tions or the third edition thank you Special thanks to Diane or ndash as always ndash
serving as a sounding board and advisor during this project
Spring 2012
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
Preface to the
Third Edition
3
Z e i l e n
Uuml b e r s a t z
b i t t e
k uuml r z e n
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7252019 CH-1Material Science of Polymers for Engineers
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Contents
Preface to the First Edition V
Preface to the Third Edition VII
983089 Introduction 983091
983089983089 The 983094 Prsquos 983091
983089983090 General Information 983094
983089983091 Identification of Polymers 983089983091
983089983092 Sustainability ndash The 983094th P 983089983093
References 983090983088
983090 Historical Background 983090983089
983090983089 From Natural to Synthetic Rubber 983090983089
983090983090 Cellulose and the $983089983088983088983088983088 Idea 983090983095
983090983091 Galalith ndash The Milk Stone 983091983088
983090983092 Leo Baekeland and the Plastics Industry 983091983089
983090983093 Herman Mark and the American Polymer Education 983091983092
983090983094 Wallace Hume Carothers and Synthetic Polymers 983091983095
983090983095 Polyethylene ndash A Product of Brain and Brawn 983091983097
983090983096 The Super Fiber and the Woman Who Invented It 983092983090
983090983097 One Last Word ndash Plastics 983092983092
References 983092983095
983091 Structure of Polymers 983092983097
983091983089 Macromolecular Structure of Polymers 983092983097983091983090 Molecular Bonds and Inter-Molecular Attraction 983093983088
983091983091 Molecular Weight 983093983089
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
7252019 CH-1Material Science of Polymers for Engineers
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 5: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/5.jpg)
7252019 CH-1Material Science of Polymers for Engineers
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VI Preface to the First Edition
are grateul to Richard Theriault or prooreading the entire manuscript We also
thank the ollowing people who helped prooread or gave suggestions during the
preparation o the book Susanne Belovari Bruce A Davis Jeffrey Giacomin Paul J
Gramann Matthew Kaegebein Gwan-Wan Lai Maria del Pilar Noriega E Antoine C
Rios B Linards U Stradins and Ester M Sun Susanne Belovari and Andrea Jung-Mack are acknowledged or translating portions o Werkstoffkunde Kunststoffe rom
German to English We also thank Tara Ruggiero or preparing the camera-ready
manuscript Many o the figures were taken rom class notes o the mechanical engi-
neering senior elective course Engineering Design with Polymers Special thanks
are offered to Lynda Litzkow Philipp Ehrenstein and Bryan Hutchinson or the
superb job o drawing those figures Matthias Mahlke o Bayer AG in Leverkusen
Germany Laura Dietsche Joseph Dooley and Kevin Hughes o Dow Chemical in Mid-
land Michigan and Mauricio DeGrei and Juan Diego Sierra o the ICIPC in Medelliacuten
Colombia are acknowledged or some o the figures Thanks are due to Marcia
Sanders or copy editing the final manuscript We are grateul to Wolgang Glenz
Martha Kuumlrzl Ed Immergut and Carol Radtke o Hanser Publishers or their support
throughout the development o this book Above all the authors thank their wives
or their patience
Summer 1995
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
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The first edition o this book was adopted by several universities in North and
South America Europe and Asia as a textbook to introduce engineering students
to the materials science o polymers The book was also translated into Japanese in
1998 Korean in 1999 and Spanish in 2008 The proessors who taught with thefirst and second editions as well as their students liked the unified approach we
took The changes and additions that were introduced in this edition are based on
suggestions rom these proessors and their students as well as rom our own
experience using it as a class textbook
Afer two revisions and two decades o teaching it has become clear that sustaina-
bility and profits are important when dealing with polymeric materials Thereore
the 4Prsquos o the first edition have expanded to the 6Prsquos in the third edition polymer
processing product perormace post-consumer lie and profit In the last 18
years this book has become a reerence or many practicing engineers most o
whom were introduced to the book as students The first and second editions were
praised because o the vast number o graphs and data that can be used as reer-
ences We have urther strengthened this attribute by expanding a comprehensive
table in the appendix that contains material property graphs or several polymers
Furthermore in this edition we added color to the figures and graphs making the
book more appealing to the reader
With this edition we owe our gratitude to Dr Christine Strohm or editing the book
and catching those small typos and inconsistencies in the text and equations Wethank Dr Nadine Warkotsch and Steffen Joerg o Hanser Publishers or their coop-
eration during the production o this book We are grateul to Luz Mayed D
Nouguez and Tobias Mattner or the superb job drawing the figures and to Tobias
Mattner or his suggestions on how to make many o the figures more understand-
able A special thanks to Katerina Saacutenchez or the graphs related to recycling o
plastics in Chapter 1 and to Nora Catalina Restrepo or generating the polymer
statistic graphs in Chapter 2 My graduate students Roberto Monroy Luisa Loacutepez
Tom Mulholland Jakob Onken Camilo Peacuterez Daniel Ramiacuterez Jochen Wellekoetter
and Yuxiao Zhang organized by William Aquite supplied extra problems and solu-
tions or the third edition thank you Special thanks to Diane or ndash as always ndash
serving as a sounding board and advisor during this project
Spring 2012
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
Preface to the
Third Edition
3
Z e i l e n
Uuml b e r s a t z
b i t t e
k uuml r z e n
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Contents
Preface to the First Edition V
Preface to the Third Edition VII
983089 Introduction 983091
983089983089 The 983094 Prsquos 983091
983089983090 General Information 983094
983089983091 Identification of Polymers 983089983091
983089983092 Sustainability ndash The 983094th P 983089983093
References 983090983088
983090 Historical Background 983090983089
983090983089 From Natural to Synthetic Rubber 983090983089
983090983090 Cellulose and the $983089983088983088983088983088 Idea 983090983095
983090983091 Galalith ndash The Milk Stone 983091983088
983090983092 Leo Baekeland and the Plastics Industry 983091983089
983090983093 Herman Mark and the American Polymer Education 983091983092
983090983094 Wallace Hume Carothers and Synthetic Polymers 983091983095
983090983095 Polyethylene ndash A Product of Brain and Brawn 983091983097
983090983096 The Super Fiber and the Woman Who Invented It 983092983090
983090983097 One Last Word ndash Plastics 983092983092
References 983092983095
983091 Structure of Polymers 983092983097
983091983089 Macromolecular Structure of Polymers 983092983097983091983090 Molecular Bonds and Inter-Molecular Attraction 983093983088
983091983091 Molecular Weight 983093983089
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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7252019 CH-1Material Science of Polymers for Engineers
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
7252019 CH-1Material Science of Polymers for Engineers
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 6: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/6.jpg)
7252019 CH-1Material Science of Polymers for Engineers
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VI Preface to the First Edition
are grateul to Richard Theriault or prooreading the entire manuscript We also
thank the ollowing people who helped prooread or gave suggestions during the
preparation o the book Susanne Belovari Bruce A Davis Jeffrey Giacomin Paul J
Gramann Matthew Kaegebein Gwan-Wan Lai Maria del Pilar Noriega E Antoine C
Rios B Linards U Stradins and Ester M Sun Susanne Belovari and Andrea Jung-Mack are acknowledged or translating portions o Werkstoffkunde Kunststoffe rom
German to English We also thank Tara Ruggiero or preparing the camera-ready
manuscript Many o the figures were taken rom class notes o the mechanical engi-
neering senior elective course Engineering Design with Polymers Special thanks
are offered to Lynda Litzkow Philipp Ehrenstein and Bryan Hutchinson or the
superb job o drawing those figures Matthias Mahlke o Bayer AG in Leverkusen
Germany Laura Dietsche Joseph Dooley and Kevin Hughes o Dow Chemical in Mid-
land Michigan and Mauricio DeGrei and Juan Diego Sierra o the ICIPC in Medelliacuten
Colombia are acknowledged or some o the figures Thanks are due to Marcia
Sanders or copy editing the final manuscript We are grateul to Wolgang Glenz
Martha Kuumlrzl Ed Immergut and Carol Radtke o Hanser Publishers or their support
throughout the development o this book Above all the authors thank their wives
or their patience
Summer 1995
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
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The first edition o this book was adopted by several universities in North and
South America Europe and Asia as a textbook to introduce engineering students
to the materials science o polymers The book was also translated into Japanese in
1998 Korean in 1999 and Spanish in 2008 The proessors who taught with thefirst and second editions as well as their students liked the unified approach we
took The changes and additions that were introduced in this edition are based on
suggestions rom these proessors and their students as well as rom our own
experience using it as a class textbook
Afer two revisions and two decades o teaching it has become clear that sustaina-
bility and profits are important when dealing with polymeric materials Thereore
the 4Prsquos o the first edition have expanded to the 6Prsquos in the third edition polymer
processing product perormace post-consumer lie and profit In the last 18
years this book has become a reerence or many practicing engineers most o
whom were introduced to the book as students The first and second editions were
praised because o the vast number o graphs and data that can be used as reer-
ences We have urther strengthened this attribute by expanding a comprehensive
table in the appendix that contains material property graphs or several polymers
Furthermore in this edition we added color to the figures and graphs making the
book more appealing to the reader
With this edition we owe our gratitude to Dr Christine Strohm or editing the book
and catching those small typos and inconsistencies in the text and equations Wethank Dr Nadine Warkotsch and Steffen Joerg o Hanser Publishers or their coop-
eration during the production o this book We are grateul to Luz Mayed D
Nouguez and Tobias Mattner or the superb job drawing the figures and to Tobias
Mattner or his suggestions on how to make many o the figures more understand-
able A special thanks to Katerina Saacutenchez or the graphs related to recycling o
plastics in Chapter 1 and to Nora Catalina Restrepo or generating the polymer
statistic graphs in Chapter 2 My graduate students Roberto Monroy Luisa Loacutepez
Tom Mulholland Jakob Onken Camilo Peacuterez Daniel Ramiacuterez Jochen Wellekoetter
and Yuxiao Zhang organized by William Aquite supplied extra problems and solu-
tions or the third edition thank you Special thanks to Diane or ndash as always ndash
serving as a sounding board and advisor during this project
Spring 2012
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
Preface to the
Third Edition
3
Z e i l e n
Uuml b e r s a t z
b i t t e
k uuml r z e n
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7252019 CH-1Material Science of Polymers for Engineers
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Contents
Preface to the First Edition V
Preface to the Third Edition VII
983089 Introduction 983091
983089983089 The 983094 Prsquos 983091
983089983090 General Information 983094
983089983091 Identification of Polymers 983089983091
983089983092 Sustainability ndash The 983094th P 983089983093
References 983090983088
983090 Historical Background 983090983089
983090983089 From Natural to Synthetic Rubber 983090983089
983090983090 Cellulose and the $983089983088983088983088983088 Idea 983090983095
983090983091 Galalith ndash The Milk Stone 983091983088
983090983092 Leo Baekeland and the Plastics Industry 983091983089
983090983093 Herman Mark and the American Polymer Education 983091983092
983090983094 Wallace Hume Carothers and Synthetic Polymers 983091983095
983090983095 Polyethylene ndash A Product of Brain and Brawn 983091983097
983090983096 The Super Fiber and the Woman Who Invented It 983092983090
983090983097 One Last Word ndash Plastics 983092983092
References 983092983095
983091 Structure of Polymers 983092983097
983091983089 Macromolecular Structure of Polymers 983092983097983091983090 Molecular Bonds and Inter-Molecular Attraction 983093983088
983091983091 Molecular Weight 983093983089
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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7252019 CH-1Material Science of Polymers for Engineers
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
7252019 CH-1Material Science of Polymers for Engineers
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
7252019 CH-1Material Science of Polymers for Engineers
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
7252019 CH-1Material Science of Polymers for Engineers
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
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7252019 CH-1Material Science of Polymers for Engineers
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The first edition o this book was adopted by several universities in North and
South America Europe and Asia as a textbook to introduce engineering students
to the materials science o polymers The book was also translated into Japanese in
1998 Korean in 1999 and Spanish in 2008 The proessors who taught with thefirst and second editions as well as their students liked the unified approach we
took The changes and additions that were introduced in this edition are based on
suggestions rom these proessors and their students as well as rom our own
experience using it as a class textbook
Afer two revisions and two decades o teaching it has become clear that sustaina-
bility and profits are important when dealing with polymeric materials Thereore
the 4Prsquos o the first edition have expanded to the 6Prsquos in the third edition polymer
processing product perormace post-consumer lie and profit In the last 18
years this book has become a reerence or many practicing engineers most o
whom were introduced to the book as students The first and second editions were
praised because o the vast number o graphs and data that can be used as reer-
ences We have urther strengthened this attribute by expanding a comprehensive
table in the appendix that contains material property graphs or several polymers
Furthermore in this edition we added color to the figures and graphs making the
book more appealing to the reader
With this edition we owe our gratitude to Dr Christine Strohm or editing the book
and catching those small typos and inconsistencies in the text and equations Wethank Dr Nadine Warkotsch and Steffen Joerg o Hanser Publishers or their coop-
eration during the production o this book We are grateul to Luz Mayed D
Nouguez and Tobias Mattner or the superb job drawing the figures and to Tobias
Mattner or his suggestions on how to make many o the figures more understand-
able A special thanks to Katerina Saacutenchez or the graphs related to recycling o
plastics in Chapter 1 and to Nora Catalina Restrepo or generating the polymer
statistic graphs in Chapter 2 My graduate students Roberto Monroy Luisa Loacutepez
Tom Mulholland Jakob Onken Camilo Peacuterez Daniel Ramiacuterez Jochen Wellekoetter
and Yuxiao Zhang organized by William Aquite supplied extra problems and solu-
tions or the third edition thank you Special thanks to Diane or ndash as always ndash
serving as a sounding board and advisor during this project
Spring 2012
Tim A Osswald Georg Menges
Madison Wisconsin USA Aachen Germany
Preface to the
Third Edition
3
Z e i l e n
Uuml b e r s a t z
b i t t e
k uuml r z e n
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7252019 CH-1Material Science of Polymers for Engineers
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Contents
Preface to the First Edition V
Preface to the Third Edition VII
983089 Introduction 983091
983089983089 The 983094 Prsquos 983091
983089983090 General Information 983094
983089983091 Identification of Polymers 983089983091
983089983092 Sustainability ndash The 983094th P 983089983093
References 983090983088
983090 Historical Background 983090983089
983090983089 From Natural to Synthetic Rubber 983090983089
983090983090 Cellulose and the $983089983088983088983088983088 Idea 983090983095
983090983091 Galalith ndash The Milk Stone 983091983088
983090983092 Leo Baekeland and the Plastics Industry 983091983089
983090983093 Herman Mark and the American Polymer Education 983091983092
983090983094 Wallace Hume Carothers and Synthetic Polymers 983091983095
983090983095 Polyethylene ndash A Product of Brain and Brawn 983091983097
983090983096 The Super Fiber and the Woman Who Invented It 983092983090
983090983097 One Last Word ndash Plastics 983092983092
References 983092983095
983091 Structure of Polymers 983092983097
983091983089 Macromolecular Structure of Polymers 983092983097983091983090 Molecular Bonds and Inter-Molecular Attraction 983093983088
983091983091 Molecular Weight 983093983089
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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7252019 CH-1Material Science of Polymers for Engineers
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
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7252019 CH-1Material Science of Polymers for Engineers
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Contents
Preface to the First Edition V
Preface to the Third Edition VII
983089 Introduction 983091
983089983089 The 983094 Prsquos 983091
983089983090 General Information 983094
983089983091 Identification of Polymers 983089983091
983089983092 Sustainability ndash The 983094th P 983089983093
References 983090983088
983090 Historical Background 983090983089
983090983089 From Natural to Synthetic Rubber 983090983089
983090983090 Cellulose and the $983089983088983088983088983088 Idea 983090983095
983090983091 Galalith ndash The Milk Stone 983091983088
983090983092 Leo Baekeland and the Plastics Industry 983091983089
983090983093 Herman Mark and the American Polymer Education 983091983092
983090983094 Wallace Hume Carothers and Synthetic Polymers 983091983095
983090983095 Polyethylene ndash A Product of Brain and Brawn 983091983097
983090983096 The Super Fiber and the Woman Who Invented It 983092983090
983090983097 One Last Word ndash Plastics 983092983092
References 983092983095
983091 Structure of Polymers 983092983097
983091983089 Macromolecular Structure of Polymers 983092983097983091983090 Molecular Bonds and Inter-Molecular Attraction 983093983088
983091983091 Molecular Weight 983093983089
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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7252019 CH-1Material Science of Polymers for Engineers
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PART 983089Basic Principles
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 2038
7252019 CH-1Material Science of Polymers for Engineers
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
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7252019 CH-1Material Science of Polymers for Engineers
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Contents
Preface to the First Edition V
Preface to the Third Edition VII
983089 Introduction 983091
983089983089 The 983094 Prsquos 983091
983089983090 General Information 983094
983089983091 Identification of Polymers 983089983091
983089983092 Sustainability ndash The 983094th P 983089983093
References 983090983088
983090 Historical Background 983090983089
983090983089 From Natural to Synthetic Rubber 983090983089
983090983090 Cellulose and the $983089983088983088983088983088 Idea 983090983095
983090983091 Galalith ndash The Milk Stone 983091983088
983090983092 Leo Baekeland and the Plastics Industry 983091983089
983090983093 Herman Mark and the American Polymer Education 983091983092
983090983094 Wallace Hume Carothers and Synthetic Polymers 983091983095
983090983095 Polyethylene ndash A Product of Brain and Brawn 983091983097
983090983096 The Super Fiber and the Woman Who Invented It 983092983090
983090983097 One Last Word ndash Plastics 983092983092
References 983092983095
983091 Structure of Polymers 983092983097
983091983089 Macromolecular Structure of Polymers 983092983097983091983090 Molecular Bonds and Inter-Molecular Attraction 983093983088
983091983091 Molecular Weight 983093983089
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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7252019 CH-1Material Science of Polymers for Engineers
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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7252019 CH-1Material Science of Polymers for Engineers
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
7252019 CH-1Material Science of Polymers for Engineers
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
7252019 CH-1Material Science of Polymers for Engineers
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
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X Contents
983091983092 Conformation and Configuration of Polymer Molecules 983093983094
983091983093 Arrangement of Polymer Molecules 983093983097
983091983093983089 Thermoplastic Polymers 983094983088
983091983093983090 Amorphous Thermoplastics 983094983088
983091983093983091 Semi-Crystalline Thermoplastics 983094983090
983091983093983092 Thermosets and Cross-Linked Elastomers 983095983090
983091983094 Copolymers and Polymer Blends 983095983091
983091983095 Polymer Additives 983095983093
983091983095983089 Flame Retardants 983095983093
983091983095983090 Stabilizers 983095983095
983091983095983091 Antistatic Agents 983095983096
983091983095983092 Fillers 983095983096
983091983095983093 Blowing Agents 983095983097
References 983096983090
983092 Thermal Properties of Polymers 983096983091
983092983089 Material Properties 983096983093
983092983089983089 Thermal Conductivity 983096983093
983092983089983090 Specific Heat 983097983089
983092983089983091 Density 983097983091
983092983089983092 Thermal Diffusivity 983097983094 983092983089983093 Linear Coefficient of Thermal Expansion 983097983095
983092983089983094 Thermal Penetration 983097983096
983092983089983095 Glass Transition Temperature 983097983097
983092983089983096 Melting Temperature 983097983097
983092983090 Measuring Thermal Data 983097983097
983092983090983089 Differential Thermal Analysis (DTA) 983089983088983088
983092983090983090 Differential Scanning Calorimeter (DSC) 983089983088983089
983092983090983091 Thermomechanical Analysis (TMA) 983089983088983091 983092983090983092 Thermogravimetry (TGA) 983089983088983092
983092983090983093 Density Measurements 983089983088983093
References 983089983088983097
983093 Rheology of Polymer Melts 983089983089983089
983093983089 Introduction 983089983089983089
983093983089983089 Continuum Mechanics 983089983089983089
983093983089983090 The Generalized Newtonian Fluid 983089983089983091983093983089983091 Normal Stresses in Shear Flow 983089983089983093
983093983089983092 Deborah Number 983089983089983094
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
7252019 CH-1Material Science of Polymers for Engineers
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
7252019 CH-1Material Science of Polymers for Engineers
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
7252019 CH-1Material Science of Polymers for Engineers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 11: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/11.jpg)
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 1538
983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
7252019 CH-1Material Science of Polymers for Engineers
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3138
983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3238
983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3338
983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 12: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/12.jpg)
7252019 CH-1Material Science of Polymers for Engineers
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XII Contents
983094983090983090 Dispersive Mixing 983089983096983092
983094983090983090983089 Break-Up of Particulate Agglomerates 983089983096983092
983094983090983090983090 Break-Up of Fluid Droplets 983089983096983094
983094983090983091 Mixing Devices 983089983096983097
983094983090983091983089 Static Mixers 983089983097983088983094983090983091983090 Banbury Mixer 983089983097983088
983094983090983091983091 Mixing in Single Screw Extruders 983089983097983090
983094983090983091983092 Co-Kneader 983089983097983092
983094983090983091983093 Twin Screw Extruders 983089983097983093
983094983090983092 Energy Consumption During Mixing 983089983097983096
983094983090983093 Mixing Quality and Efficiency 983089983097983097
983094983090983094 Plasticization 983090983088983089
983094983091 Injection Molding 983090983088983094983094983091983089 The Injection Molding Cycle 983090983088983095
983094983091983090 The Injection Molding Machine 983090983089983088
983094983091983090983089 The Plasticating and Injection Unit 983090983089983088
983094983091983090983090 The Clamping Unit 983090983089983089
983094983091983090983091 The Mold Cavity 983090983089983091
983094983092 Special Injection Molding Processes 983090983089983094
983094983092983089 Multi-Component Injection Molding 983090983089983094
983094983092983090 Co-Injection Molding 983090983089983096
983094983092983091 Gas-Assisted Injection Molding (GAIM) 983090983089983097983094983092983092 Injection-Compression Molding 983090983090983089
983094983092983093 Reaction Injection Molding (RIM) 983090983090983090
983094983092983094 Liquid Silicone Rubber Injection Molding 983090983090983093
983094983093 Secondary Shaping 983090983090983094
983094983093983089 Fiber Spinning 983090983090983094
983094983093983090 Film Production 983090983090983095
983094983093983090983089 Cast Film Extrusion 983090983090983095
983094983093983090983090 Film Blowing 983090983090983096983094983093983091 Blow Molding 983090983091983088
983094983093983091983089 Extrusion Blow Molding 983090983091983088
983094983093983091983090 Injection Blow Molding 983090983091983090
983094983093983091983091 Thermoforming 983090983091983091
983094983094 Calendering 983090983091983093
983094983095 Coating 983090983091983096
983094983096 Compression Molding 983090983092983088
983094983097 Foaming 983090983092983090
983094983089983088 Rotational Molding 983090983092983092
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 1338
983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
7252019 CH-1Material Science of Polymers for Engineers
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 1538
983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 13: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/13.jpg)
7252019 CH-1Material Science of Polymers for Engineers
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983094983089983089 Computer Simulation in Polymer Processing 983090983092983093
983094983089983089983089 Mold Filling Simulation 983090983092983094
983094983089983089983090 Orientation Predictions 983090983092983096
983094983089983089983091 Shrinkage and Warpage Predictions 983090983092983097
References 983090983094983088
983095 Anisotropy Development During Processing 983090983094983091
983095983089 Orientation in the Final Part 983090983094983091
983095983089983089 Processing Thermoplastic Polymers 983090983094983091
983095983089983090 Processing Thermoset Polymers 983090983095983089
983095983090 Predicting Orientation in the Final Part 983090983095983093
983095983090983089 Planar Orientation Distribution Function 983090983095983094
983095983090983090 Single Particle Motion 983090983095983096 983095983090983091 Jefferyrsquos Model 983090983095983097
983095983090983092 Folgar-Tucker Model 983090983096983088
983095983090983093 Tensor Representation of Fiber Orientation 983090983096983089
983095983090983093983089 Predicting Orientation in Complex Parts Using
Computer Simulation 983090983096983090
983095983091 Fiber Damage 983090983096983095
References 983090983097983091
983096 Solidification of Polymers 983090983097983093
983096983089 Solidification of Thermoplastics 983090983097983093
983096983089983089 Thermodynamics During Cooling 983090983097983093
983096983089983090 Morphological Structure 983090983097983097
983096983089983091 Crystallization 983091983088983088
983096983089983092 Heat Transfer During Solidification 983091983088983091
983096983090 Solidification of Thermosets 983091983088983095
983096983090983089 Curing Reaction 983091983088983096983096983090983090 Cure Kinetics 983091983088983097
983096983090983091 Heat Transfer During Cure 983091983089983092
983096983091 Residual Stresses and Warpage of Polymeric Parts 983091983089983094
983096983091983089 Residual Stress Models 983091983089983097
983096983091983089983089 Residual Stress Model Without Phase Change Effects 983091983090983089
983096983091983089983090 Model to Predict Residual Stresses with
Phase Change Effects 983091983090983090
983096983091983090 Other Simple Models to Predict Residual Stresses and Warpage 983091983090983092983096983091983090983089 Uneven Mold Temperature 983091983090983094
983096983091983090983090 Residual Stress in a Thin Thermoset Part 983091983090983095
983096983091983090983091 Anisotropy Induced Curvature Change 983091983090983096
Contents XIII
7252019 CH-1Material Science of Polymers for Engineers
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 1538
983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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7252019 CH-1Material Science of Polymers for Engineers
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
7252019 CH-1Material Science of Polymers for Engineers
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
7252019 CH-1Material Science of Polymers for Engineers
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
7252019 CH-1Material Science of Polymers for Engineers
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
7252019 CH-1Material Science of Polymers for Engineers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
7252019 CH-1Material Science of Polymers for Engineers
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 14: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/14.jpg)
7252019 CH-1Material Science of Polymers for Engineers
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XIV Contents
983096983091983091 Predicting Warpage in Actual Parts 983091983090983097
References 983091983091983094
983097 Mechanical Behavior of Polymers 983091983092983089
983097983089 Basic Concepts of Stress and Strain 983091983092983089
983097983089983089 Plane Stress 983091983092983090
983097983089983090 Plane Strain 983091983092983091
983097983090 Viscoelastic Behavior of Polymers 983091983092983091
983097983090983089 Stress Relaxation Test 983091983092983092
983097983090983090 Time-Temperature Superposition (WLF-Equation) 983091983092983094
983097983090983091 The Boltzmann Superposition Principle 983091983092983095
983097983091 Applying Linear Viscoelasticity to Describe the Behavior of Polymers 983091983092983096
983097983091983089 The Maxwell Model 983091983092983097
983097983091983090 Kelvin Model 983091983093983088
983097983091983091 Jeffrey Model 983091983093983090
983097983091983092 Standard Linear Solid Model 983091983093983092
983097983091983093 The Generalized Maxwell Model 983091983093983094
983097983092 The Short-Term Tensile Test 983091983094983089
983097983092983089 Rubber Elasticity 983091983094983090
983097983092983090 The Tensile Test and Thermoplastic Polymers 983091983094983095
983097983093 Creep Test 983091983095983092
983097983093983089 Isochronous and Isometric Creep Plots 983091983095983096
983097983094 Dynamic Mechanical Tests 983091983095983097
983097983094983089 Torsion Pendulum 983091983095983097
983097983094983090 Sinusoidal Oscillatory Test 983091983096983091
983097983095 Effects of Structure and Composition on Mechanical Properties 983091983096983093
983097983095983089 Amorphous Thermoplastics 983091983096983093
983097983095983090 Semi-Crystalline Thermoplastics 983091983096983096
983097983095983091 Oriented Thermoplastics 983091983097983088983097983095983092 Crosslinked Polymers 983091983097983093
983097983096 Mechanical Behavior of Filled and Reinforced Polymers 983091983097983095
983097983096983089 Anisotropic Strain-Stress Relation 983091983097983097
983097983096983090 Aligned Fiber Reinforced Composite Laminates 983092983088983088
983097983096983091 Transformation of Fiber Reinforced Composite Laminate
Properties 983092983088983090
983097983096983092 Reinforced Composite Laminates with a Fiber Orientation
Distribution Function 983092983088983092983097983097 Strength Stability Under Heat 983092983088983093
References 983092983090983089
7252019 CH-1Material Science of Polymers for Engineers
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 15: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/15.jpg)
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983089983088 Failure and Damage of Polymers 983092983090983091
983089983088983089 Fracture Mechanics 983092983090983091
983089983088983089983089 Fracture Predictions Based on the Stress Intensity Factor 983092983090983092
983089983088983089983090 Fracture Predictions Based on an Energy Balance 983092983090983094
983089983088983089983091 Linear Viscoelastic Fracture Predictions Based on J -Integrals 983092983090983096
983089983088983090 Short-Term Tensile Strength 983092983091983088
983089983088983090983089 Brittle Failure 983092983091983088
983089983088983090983090 Ductile Failure 983092983091983092
983089983088983090983091 Failure of Highly Filled Systems or Composites 983092983091983095
983089983088983091 Impact Strength 983092983092983088
983089983088983091983089 Impact Test Methods 983092983092983094
983089983088983091983090 Fracture Mechanics Analysis of Impact Failure 983092983093983088
983089983088983092 Creep Rupture 983092983093983093
983089983088983092983089 Creep Rupture Tests 983092983093983094
983089983088983092983090 Fracture Mechanics Analysis of Creep Rupture 983092983093983097
983089983088983093 Fatigue 983092983093983097
983089983088983093983089 Fatigue Test Methods 983092983094983088
983089983088983093983090 Fracture Mechanics Analysis of Fatigue Failure 983092983094983096
983089983088983094 Friction and Wear 983092983095983088
983089983088983095 Stability of Polymer Structures 983092983095983091983089983088983096 Environmental Effects on Polymer Failure 983092983095983093
983089983088983096983089 Weathering 983092983095983093
983089983088983096983090 Chemical Degradation 983092983096983088
983089983088983096983091 Thermal Degradation of Polymers 983092983096983090
References 983092983096983094
983089983089 Electrical Properties of Polymers 983092983096983097
983089983089983089 Dielectric Behavior 983092983096983097983089983089983089983089 Dielectric Coefficient 983092983096983097
983089983089983089983090 Mechanisms of Dielectrical Polarization 983092983097983091
983089983089983089983091 Dielectric Dissipation Factor 983092983097983094
983089983089983089983092 Implications of Electrical and Thermal Loss in a Dielectric 983092983097983097
983089983089983090 Electric Conductivity 983093983088983088
983089983089983090983089 Electric Resistance 983093983088983088
983089983089983090983090 Physical Causes of Volume Conductivity 983093983088983089
983089983089983091 Application Problems 983093983088983092983089983089983091983089 Electric Breakdown 983093983088983092
983089983089983091983090 Electrostatic Charge 983093983088983096
Contents XV
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
7252019 CH-1Material Science of Polymers for Engineers
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
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XVI Contents
983089983089983091983091 Electrets 983093983088983097
983089983089983091983092 Electromagnetic Interference Shielding (EMI Shielding) 983093983088983097
983089983089983092 Magnetic Properties 983093983089983088
983089983089983092983089 Magnetizability 983093983089983088
983089983089983092983090 Magnetic Resonance 983093983089983088
References 983093983089983089
983089983090 Optical Properties of Polymers 983093983089983091
983089983090983089 Index of Refraction 983093983089983091
983089983090983090 Photoelasticity and Birefringence 983093983089983094
983089983090983091 Transparency Reflection Absorption and Transmittance 983093983090983088
983089983090983092 Gloss 983093983090983094983089983090983093 Color 983093983090983095
983089983090983094 Infrared Spectroscopy 983093983091983089
983089983090983095 Infrared Pyrometry 983093983091983090
983089983090983096 Heating with Infrared Radiation 983093983091983092
References 983093983091983094
983089983091 Permeability Properties of Polymers 983093983091983095 983089983091983089 Sorption 983093983091983095
983089983091983090 Diffusion and Permeation 983093983091983097
983089983091983091 Measuring S D and P 983093983092983092
983089983091983092 Corrosion of Polymers and Cracking [983093] 983093983092983093
983089983091983093 Diffusion of Polymer Molecules and Self-diffusion 983093983092983096
References 983093983092983096
983089983092 Acoustic Properties of Polymers 983093983092983097
983089983092983089 Speed of Sound 983093983092983097
983089983092983090 Sound Reflection 983093983093983089
983089983092983091 Sound Absorption 983093983093983090
References 983093983093983091
Appendix 983093983093983093
Appendix I 983093983093983094
Appendix II 983093983094983092
Appendix III 983093983094983093
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
7252019 CH-1Material Science of Polymers for Engineers
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
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Appendix IV ndash Balance Equations 983093983096983091
Continuity Equation 983093983096983091
Energy Equation for a Newtonian Fluid 983093983096983091
Momentum Balance 983093983096983092
Momentum Equation in Terms of τ 983093983096983092Navier-Stokes Equation 983093983096983092
Index 983093983096983095
Contents XVII
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
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7252019 CH-1Material Science of Polymers for Engineers
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 19: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/19.jpg)
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PART 983089Basic Principles
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 20: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/20.jpg)
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 21: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/21.jpg)
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1As the word itsel suggests polymers1 are materials composed o many molecules
or parts that result in long chains These large molecules are generally reerred to
as macromolecules The unique material properties o polymers and the versatility
o their processing methods are attributed to their molecular structure For many
applications the ease with which polymers and plastics 2 are processed makes
them the most sought-afer material today Because o their relatively low density
and their ability to be shaped and molded at relatively low temperatures compared
to traditional materials such as metals plastics and polymers are the material o
choice when integrating several parts into a single component ndash a design aspect
usually called part consolidation In act parts and components that have tra-
ditionally been made o wood metal ceramic or glass are redesigned or plastics
on a daily basisHowever the properties o a finished product depend not only on the choice o
material and additives but also on the process used to manuacture the part The
relation that exists between the material and product perormance is reerred to as
the 6 Prsquos Polymer Process Product Performance Post-consumer Life and Profit
This approach and philosophy is used throughout this book
11 The 6 Prsquos
As a result o years o experience in plastics engineering a technique has emerged
that the authors ofen reer to as the 6 Prsquos Basically this approach which is used
throughout this book states that when addressing any one particular o the 6 Prsquos
all other Prsquos must be taken into account To design a product exhibiting a desired
performance at a specific cost (profit) the material (plastic) and the manuacturing
1 From the Greek poli which means many andmeros which means parts
2 The term ldquoplasticsrdquo describes a compound o polymers and various additives fillers and reinorcing
agents
Introduction
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
7252019 CH-1Material Science of Polymers for Engineers
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 22: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/22.jpg)
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983092 1 Introduction
technique (process) as well as sustainability issues (post-consumer life) must be
considered The 6 Prsquos is a way to uniy polymer or plastics engineering not only
or students in the classroom but also or practicing engineers and researchers
Figure 11 presents a summary o the 6 Prsquos Each o the 6 Prsquos can be described
individually
Plastic Plastic signifies the molecule the material used and additives such as
fillers fibers pigments mold release agents to name a ew
Process The process can be extrusion injection molding compression molding
or any other process during which the polymeric material is heated melted
mixed pumped shaped and solidified As a result o the thermal history and the
deormation the material in the final part will exhibit a certain morphology a
molecular or filler orientation and even a certain level o degradation that may
influence the properties o the material in the product Product The product can be a pellet a film a fiber a component or an assembly
Performance The product needs to ulfill certain requirements such as with-
standing a thermal load exhibiting specific mechanical properties or having a
certain optical quality to name a ew Furthermore all this may be required in
an environment that can be damaging to the plastic product
Polymer
Post-consumer Life
Performance
Product
Process
MoleculeFillersFibersAdditives
ExtrusionInjectionCompression
CompatibilityAdhesionRegulationLegislation
Properties of polymerProperties of fiberProperties of additives
HeatingMixingPumpingForming
MorphologyOrientationDegradation
PelletFilmFiberComponentAssembly
ThermalMechanicalOpticalEnvironmental
RecyclingEnvironment
SustainabilityRegulationLegislation
Profit
Material costDie and mold costMachine and energy costLabor and automation cost
Figure 11 The 6 Prsquos
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
7252019 CH-1Material Science of Polymers for Engineers
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
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7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 23: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/23.jpg)
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983089983089 The 983094 Prsquos 983093
Profit The success o any product or project is measured by how this product
contributes to the bottom line profits The cost o a product is one o many ac-
tors determining the success o a product It depends on material costs mold and
die costs machine costs and labor costs decisions about automation versus
labor play a significant role
Post-consumer life and Sustainability Today post-consumer lie is primarily
concerned with recycling However issues such as environmental impact and
sustainability should be in every engineerrsquos mind when designing a plastic
product or developing a material to manuacture the product Furthermore engi-
neers should always stay one step ahead o legislation and government regula-
tions regarding products materials and additives
Figure 12 is an illustrative example o how the 6 Prsquos are interrelated within a
single design It depicts an assembly injection molded saety gear clutch where aninner gear is injection molded first and then overmolded with an outer gear The
outer gear shrinks over the inner gear generating sufficient residual hoop stress
to orce the two gears together The combination o the hoop stress between the
gears and the coefficient o riction between the two materials used to mold the
gears results in a maximum torque that the two gears can be subjected to beore
they start sliding past each other One application or such a system is the saety
device or side mirrors in an automobile that allows them to rotate beore breaking
Polymer
Post-consumer Life Performance
Product
(1) Flow
(3) Heat transfer(5) Fiber orientation
(6) Fiber damage
(7) Degradation
(2) Rheological properties
(4) Thermal properties(10) Mechanical properties
(14) Friction coefficients
(12) Assembly(13) Functionality
(15) Disassembly
(16) Choice of materials(17) Regulations and legislation
(8) Anisotropy
(9) Mechanical behavior
(11) Stresses
Process
Profit(18) Material cost
(19) Mold cost(20) Machine cost
(21) Energy cost(22) Value of recycled material
Figure 12 The 6 Prsquos and an assembly injection molded clutch gear (Courtesy Institute or
Plastics Technology (LKT) University o Erlangen-Nuremberg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
7252019 CH-1Material Science of Polymers for Engineers
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 24: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/24.jpg)
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983094 1 Introduction
Figure 12 presents a filled mold (right) and a short shot (lef) The short shot shows
how the polymer (1) flows during mold filling The flow depends on the (2) rheo-
logical properties o the polymer melt which in turn depends on the (3) heat trans-
fer inside the cavity The heat transer is dependent on the (4) thermal properties o
the polymer The deormation during flow causes (5) fiber orientation (6) fiber dam- age and possibly (7) material degradation The orientation and fiber length dis-
tribution resulting rom the fiber damage lead to (8) anisotropy in the finished
product that determines the (9) mechanical behavior o the part The anisotropic
mechanical behavior o the finished product depends on the combined (10) mechan-
ical properties o the basic materials that compose the original resin The final
mechanical properties control the (11) stresses and mechanical response o the
(12) assembly and its (13) functionality In turn the maximum torque within this
system is also controlled by the (14) friction coefficients o the materials At the end
o its service lie it may be necessary to (15) disassemble the gears i the (16)
choice of materials does not permit recycling o the assembled part Furthermore
at the end o product service lie the (17) regulations and legislations may have
changed perhaps banning the use o a specific material or additive Furthermore
the (18) material cost (19) mold cost (20) machine or molding costs (21) energy
consumption during processing and the (22) value of the recovered resin from sprue
and runner systems as well as from post-service life recycling are all o extreme
importance
12 General Information
Plastics have become the most important material in many fields and applications
They are lightweight some have excellent optical properties some are electric and
thermal insulators and in general they are easier and less expensive to make and
to process into a final product Some o their properties exceed the properties omore traditional materials while in other areas they are no match to conventional
engineering materials Figure 13 compares polymers to other materials with steel
providing the reerence (= 10) While the mechanical properties o steel aluminum
and ceramics all clearly outperorm those o thermoplastics thermoplastic mate-
rials are much lighter can be processed at significantly lower temperatures and
are excellent thermal insulators
Polymers are differentiated in three categories thermoplastics thermosets or
elastomers Thermoplastics in turn include a special amily called thermoplastic
elastomers However all these material have in common that they are made o
large molecules Some o these molecules are not crosslinked which means that
each molecule can move reely relative to its neighbors and others are crosslinked
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
7252019 CH-1Material Science of Polymers for Engineers
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
7252019 CH-1Material Science of Polymers for Engineers
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
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983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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7252019 CH-1Material Science of Polymers for Engineers
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 25: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/25.jpg)
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983089983090 General Information 983095
which means that ldquobridgesrdquo or physical links interconnect the polymer molecules
Thermoplastics and un-vulcanized elastomers are non-crosslinked Vulcanized
rubbers or elastomers and thermosets are crosslinked
Thermoplastics are polymers that solidiy as they are cooled no longer allowing
the long molecules to move reely and when heated again these materials regain
the ability to ldquoflowrdquo as the molecules are able to slide past each other with ease
Thermoplastic polymers are divided into two classes amorphous and semi-crystal-
line polymers Amorphous thermoplastics are those with molecules that remain
in disorder as they cool leading to materials with a airly random molecular struc-
tures An amorphous polymer solidifies or vitrifies as it is cooled below its glass
transition temperature T g Semi-crystalline thermoplastics on the other hand
solidiy while establishing a certain order in their molecular structure Hence asthey are cooled they harden when the molecules begin to arrange in a regular
order below what is usually reerred to as the melting temperature T m The mole-
cules in semi-crystalline polymers that are not transormed into ordered regions
remain in small amorphous regions These amorphous regions within the semi-
crystalline domains lose their ldquoflowabilityrdquo below their glass transition tempera-
ture Most semi-crystalline polymers have a glass transition temperature at subzero
temperatures hence behaving like rubbery or leathery materials at room tempe-
rature On the other hand thermosetting polymers solidiy by a chemical curing
process Here the long macromolecules crosslink with each other during curing
resulting in a network o molecules that cannot slide past each other The orma-
tion o these networks causes the material to lose the ability to ldquoflowrdquo even afer
Figure 13 Properties o thermoplastics aluminum and ceramics with respect to steel
(Courtesy E Schmachtenberg)
Density
0001
Pricedm3
Pricekg
Strength
Stiffness
Thermal expansion
Thermal conductivity
Melting temperature
10010100001001
Properties with respect to steel (steel = 10)
Thermoplastics
Aluminum
Ceramics
Steel
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
7252019 CH-1Material Science of Polymers for Engineers
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
7252019 CH-1Material Science of Polymers for Engineers
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 2938
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3038
983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
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983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
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Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
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983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 26: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/26.jpg)
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983096 1 Introduction
reheating A high crosslinking density between the molecules makes thermo-
setting materials stiff and brittle Thermosets also exhibit a glass transition tem-
perature that is sometimes near or above thermal degradation temperatures The
crosslinks between the molecules are chemical bonds such as covalent and ionic
bonds Another general type o bond between molecules in polymers is a physicalbond such as van der Waals forces Finally another type o bond is the hydrogen
bond that results rom the attraction between a hydrogen atom and an electro-
negative atom such as oxygen or nitrogen The highest bond strength results rom
a chemical bond and the lowest rom a physical bond [1]
Compared to thermosets elastomers are only lightly crosslinked which permits
almost ull extension o the molecules However the links across the molecules
hinder them rom sliding past each other making even large deormations rever-
sible One common characteristic o elastomeric materials is that the glass tran-sition temperature is much lower than room temperature Their ability to ldquoflowrdquo is
lost afer they are vulcanized or crosslinked Because at room temperature
crosslinked elastomers are significantly above their glass transition temperature
they are very sof and very compliant elastic solids
Table 11 presents the most common amorphous and semi-crystalline thermoplas-
tics as well as thermosets and elastomers with some o their applications Table
12 presents many polymers and their ISO abbreviations Today polymers are
ound everywhere The skier in Fig 14 presents just one example o where we can
find polymers in everyday lie He is protected by a helmet that is composed o
various polymer components His skiing equipment is also composed o a variety
o polymers and polymer composites and he is keeping warm using layers o
polymer abrics and insulating materials It should be pointed out that not all the
polymer components the skier is wearing are listed in the figure and that in
addition to the specific polymers listed in Fig 14 there are many more options o
polymeric materials to choose rom For example some skiing boots are reinorced
with aramid fibers
There are thousands o different grades o polymers available to the design engi-neer These materials cover a wide range o properties rom sof to hard ductile to
brittle and weak to tough Figure 15 shows this range by plotting important aver-
age properties or selected polymers The values corresponding to each material in
Fig 15 represent only an average There is a wide range in properties even or
materials o the same class The range in properties is ofen increased by the di-
erent additives and fillers that a resin may contain At this point it is important to
note that the properties listed in Fig 15 should not be used or design decisions
The properties represent a general trend in stiffness and toughness o the various
materials and should be used only when comparing one material against another
As will be discussed in later chapters properties that are used in design need to be
time-dependent such that loading time or loading rate can be included as design
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983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
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983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3138
983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3238
983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3338
983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 27: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/27.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 2738
983089983090 General Information 983097
Table 11 Common Polymers and Some o Their Applications
Polymer Applications
Thermoplastics
Amorphous
Polystyrene Mass-produced transparent articles thermoormed packaging
oamed packaging and thermal insulation products etc
Polymethyl methacrylate Skylights airplane windows lenses bulletproo windows
automotive stop lights etc
Polycarbonate Helmets eyeglass lenses CDrsquos hockey masks bulletproo
windows blinker lights head lights etc
Unplasticized polyvinyl chloride Tubes window rames siding rain gutters bottles thermoormed
packaging etc
Plasticized polyvinyl chloride Shoes hoses roto-molded hollow articles such as balls and other
toys calendered films or raincoats and tablecloths etcSemi-crystalline
High density polyethylene Milk and soap bottles mass production o household goods o
higher quality tubes paper coating etc
Low density polyethylene Mass production o household goods squeeze bottles grocery
bags etc
Polypropylene Goods such as suitcases tubes engineering application
(fiberglass-reinorced) housings or electric appliances etc
Polytetrafluoroethylene Coating o cooking pans lubricant-ree bearings etc
Polyamide Bearings gears bolts skate wheels pipes fishing line textiles
ropes etc
Thermosets
Epoxy Adhesive glass fiber reinorced automotive lea springs carbon
fiber reinorced bicycle rames aircraf wings and uselage etc
Melamine Decorative heat-resistant suraces or kitchens and urniture
dishes etc
Phenolics Heat-resistant handles or pans irons and toasters electric
outlets etc
Unsaturated polyester Toaster sides iron handles satellite dishes glass fiber reinorced
breaker switch housings and automotive body panels etc
Elastomers
Polybutadiene Automotive tires (blended with natural rubber and styrene
butadiene rubber) gol ball skin etc
Ethylene propylene rubber Automotive radiator hoses and window seals roo covering etc
Natural rubber (polyisoprene) Automotive tires engine mounts etc
Polyurethane elastomer Roller skate wheels sport arena floors ski boots automotive
seats (oamed) shoe soles (oamed) etc
Silicone rubber Seals parts or medical applications membranes heat resistant
kitchen containers etc
Styrene butadiene rubber Automotive tire treads etc
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 2838
983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 2938
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3038
983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3138
983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3238
983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3338
983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 28: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/28.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 2838
983089983088 1 Introduction
Table 12 Abbreviations o Common Polymers (TP = thermoplastic E = elastomer
TS = thermoset)
Polymer Abbrev (Type) Polymer Abbrev (Type)
Acrylonitrile-butadiene-styrene ABS (TP) Polyether ether ketone PEEK (TP)
Butadiene rubber BR (E) Polyether sulone PES (TP)
Cellulose acetate CA (TP) Polyethylene
terephthalate
PET (TP)
Cellulose acetate butyrate CAB (TP) Polyimide PI (TP)
Cellulose nitrate CN (TP) Polyisobutylene PIB (TP)
Epoxy EP (TS) Polymethyl
methacrylate
PMMA (TP)
Ethylene-propylene-diene rubber EPDM (E) Polyphenylene sulfide PPS (TP)
Expanded polystyrene EPS (TP) Polyphenylene sulone PPSU (TP)
High density polyethylene PE-HD (TP) Polypropylene PP (TP)
Impact resistant polystyrene PS-HI (TP) Polypropylene
copolymer
PP-CO (TP)
Linear low density polyethylene PE-LLD (TP) Polystyrene PS (TP)
Linear medium density polyethylene PE-LMD (TP)
Liquid crystalline polymer LCP (TP) Polysulone PSU (TP)
Low density polyethylene PE-LD (TP) Polytetrafluoroethylene PTFE (TP)
Melamine-ormaldehyde MF (TS) Polyurethane PUR (TS)
Metallocene catalyzed polyethylene mPE (TP) Polyvinylidene acetate PVAC (TP)
Natural rubber NR (E) Polyvinyl alcohol PVAL (TP)
Olefinic thermoplastic elastomer TPO (TP) Polyvinyl carbazole PVK (TP)
Phenol-ormaldehyde (phenolic) PF (TS) Polyvinyl chloride PVC (TP)
PF mineral filled moldings PF-m (TS) Polyvinylidene fluoride PVDF (TP)
PF organic filled moldings PF-o (TS) Rigid PVC PVC-U (TP)
Plasticized PVC PVC-P (TP) Silicone SI (E)
Polyacetal (polyoxymethylene) POM (TP) Silicone rubber SI (E)
Polyacrylate PAR (TP) Styrene-acrylonitrile
copolymer
SAN (TP)
Polyacrylonitrile PAN (TP) Thermoplastic
elastomer
TPE (TP)
Polyamide 6 PA6 (TP) Thermoplastic poly-
urethane elastomer
TPU (TP)
Polyamide 66 PA66 (TP) Unsaturated polyester UP (TS)
Polybutylene terephthalate PBT (TP) Urea-ormaldehyde UF (TS)
Polycarbonate PC (TP) Vinyl ester resin VE (TP)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 2938
7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
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httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3138
983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3238
983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
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httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3338
983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
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983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 29: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/29.jpg)
7252019 CH-1Material Science of Polymers for Engineers
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7252019 CH-1Material Science of Polymers for Engineers
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983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3138
983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3238
983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3338
983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 30: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/30.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3038
983089983090 1 Introduction
100
10
1000 20
15
10
10
10
100
1000
Elongationat break
at 23degC ASTM D 638
IZOD impactstrength
Jm (notched 23degC) ASTM D 256
Specific gravity ASTM D 792
HIPS HIPS
HIPS
PP
PP
PP
PC PC
PC
PVC
PVC
PVC
Epoxy
Epoxy
EpoxyPhenolic
Phenolic
Phenolic
POM
POM
POM
PMMA
PMMA
PMMA
PET
PET
PET
PA66
PA66PA66
HDPE
HDPE
HDPE
LDPE
LDPE no break
LDPE
05
PSPS
PS
SANSAN
SAN
ABS
ABS
ABS
PTFE
PTFE
PTFE
PI
PI
PI
UP
UP
UP
20
Market price $ lb(March 2010)
300
200
100
00
5
10
15200
150
100
50
0
1000
10000
100
Deflectiontemperature degCunder flexuralload (182 MPa) ASTM D 648
Thermalexpansioncoefficient
10-5 mm degC ASTM D 696
Tensilestrength MPaat 23degC ASTM D 638
Flexuralmodulus MPaat 23degC ASTM D 790
HIPS
HIPS
HIPS
HIPSPP
PP
PP
PP
PC PC
PC
PC PVC
PVC
PVC
PVC
Epoxy
Epoxy
Epoxy
EpoxyPhenolic
PhenolicPhenolic
Phenolic
POM
POM
POM
POM
PMMA
PMMA
PMMA
PMMA
PET
PET
PET
PET
PA66
PA66
PA66
PA66
HDPE
HDPE
HDPE
HDPELDPE
LDPE
LDPE
LDPEPS
PS
PS
PS
SAN
SAN
SAN
SAN
ABS
ABS
ABS
ABS
PTFE
PTFE
PTFE
PTFE
PI
PI
PI
PI
UP
UP
UP
UP
20
10
15
10
07PETHDPE Phenolic
LDPEPS
PMMA
HIPS
PI
EpoxyPP
SAN
UP
PVC
PC
ABSPOM
PTFE
PA66
ABS HDPEPET Recycled
grades
Figure 15 Average properties or common polymers
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3138
983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3238
983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3338
983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 31: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/31.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3138
983089983091 Identification of Polymers 983089983091
13 Identification of Polymers
Perhaps one o the most important skills a plastics design engineer needs to haveis the ability to identiy a specific polymer or polymer component An experienced
plastics engineer can ofen identiy a polymer by touching smelling or tapping it
However the complete identification o the chemical composition additives and
fillers o a plastic material is an extremely complicated task To achieve this equip-
ment that perorms differential scanning calorimetry inrared spectroscopy and
dynamic mechanical analysis to name a ew is available3 Most process and design
engineers do not have these measuring devices at hand nor do they have the ana-
lytical experience to run them and interpret the resulting data However ofen only
simple means are needed in addition to basic knowledge o polymer chemistry to
identiy a polymer Through simple observation a burn test and experience an
engineer is able to identiy most plastics Figure 16 presents a summarized guide
to aid in the identification o polymers
Inormation presented in guides such as in Fig 16 are only helpul when used
with common sense and engineering insight For example the attribute labeled
ldquoAppearancerdquo can sometimes be misleading Depending on the additives or color-
ants added even an amorphous thermoplastic such as polystyrene can be opaque
The stiffness attribute is broken down into three categories flexible semi-rigidand rigid Flexible are those materials that eel rubbery or leathery while mate-
rials are semi-rigid when they are strong and stiff but can deflect a substantial
amount The materials that all under the rigid category are those that are stiff but
brittle During the burn test make sure not to inhale the umes released by a burn-
ing plastic or those released soon afer extinguishing the burning polymer Even
without directly inhaling the umes one can still discern the particular smells o
the material during the burning test Due to the benzene ring in their molecular
structure styrenic materials such as PS ABS and SAN have a sweet smell while
polyolefin plastics such as PE and PP smell waxy Because o the nitrogen atoms in
their structure polyamides can smell like burning hair When burning POM a
strong smell o ormaldehyde is released Burning PVC releases HCl To no sur-
prise cellulose plastics smell like burning paper All burn tests must be perormed
under a ventilation hood or in a well ventilated room
3 These tests are discussed in detail in Chapters 3 and 8 o this book
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3238
983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3338
983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 32: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/32.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3238
983089983092 1 Introduction
Appearance SurfaceStiffness Burn test
T r a n s p a r e n t
T r a n s p a r e n t ( t h i n f i l m )
T r a n s l u s c e n t
O p a q u e
F l e x i b l e ( r e s i l i e n t )
S e m i - r i g i d
R i g i d ( B r i t t l e )
G l a s s y
W a x y
D u l l
B l a c k s o o t
B u r n s c l e a n
S e l f e x t i n g u i s h i n g
D r i p s
D o e s n o t d r i p
Y e l l o w f l a m e
B l u e f l a m e
G r e e n f l a m e
PE-LD
PE-HD
PP
PP-CO
PS
PS-HI
SAN
ABS
PVC-R
PVC-P
PTFE
PVDF
PVAC
PVAL
PMMAPOM
PA6
PA66
PSU
PI
CA
CAB
CN
PCPET
PBT
PF
PF-MF
PF-OF
UP
EP
PUR
SI
Figure 16 Plastics identification attributes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3338
983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 33: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/33.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3338
983089983092 Sustainability ndash The 983094th P 983089983093
14 Sustainability ndash The 6th P
The first edition o this book was published at the end o the 20th century when theterm bdquosustainabilityldquo was used by only a ew and recycling o plastics was starting
to become a topic o environmental and economic interest Today 15 years afer the
publication o that first edition and already in the second decade o the 21st
century we live in a world that is orced to think and act with the environment in
mind While topics such as biopolymers biodegradability and biocompatibility are
playing an increasingly more important role in this arena recycling is the main
topic that we consider within the 6th P Post-consumer lie
We can divide plastics recycling into two major categories industrial and postcon-sumer plastic scrap recycling Industrial scrap is easily recycled and re-introduced
into the manuacturing stream either within the same company as a regrind or
sold to third parties as a homogeneous reliable and uncontaminated source o
resin Post-consumer plastic scrap recycling requires the material to go through a
ull lie cycle prior to being reclaimed This lie cycle can last rom a ew days or
packaging material to several years or electronic equipment housing material
Post-consumer plastic scrap can origin rom commercial agricultural or muni-
cipal waste Municipal plastic scrap primarily consists o packaging waste but also
plastics rom de-manuactured retired appliances and electronic equipment
Post-consumer plastic scrap recycling requires collecting handling cleaning sort-
ing and grinding Availability and collection o post-consumer plastic scrap is per-
haps one o the most critical aspects Today the demand or recycled plastics is
higher than the availability o these materials Although the availability o HDPE
rom bottles has seen a slight increase the availability o recycled PET bottles has
decreased in the last ew years One o the main reasons or the decrease o post-
consumer PET is the act that single-serving PET bottles are primarily consumed
outside o the home making recycling and collection more difficult On the other
hand HDPE bottles which come rom milk containers soap and cleaner bottles
are consumed in the home and are thereore thrown into the recycling bin by the
consumer A crucial issue when collecting plastic waste is identiying the type o
plastic used to manuacture the product Packaging is ofen identified with the
standard SPI identification symbol which contains the triangular-shaped recyc-
ling arrows and a number between 1 and 7 Ofen this is accompanied by the
abbre viated name o the plastic Table 13 and Fig 17 present the seven commonly
recycled plastic materials in the United States along with the characteristics o
each plastic the main sources or packaging applications and the common appli-cations or the recycled materials Electronic housings are ofen identified with a
molded-in name o the polymer used such as ABS as well as an identifier that
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 34: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/34.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3438
983089983094 1 Introduction
Table 13 Plastics Characteristics Applications and Use Afer Recycling
Codes Characteristics Packaging Applications Recycled Products
(1) PET Clarity strength
toughness barrier to
gas and moisture
resistance to heat
Plastic bottles or sof drink
water sports drink beer
mouthwash catsup and salad
dressing peanut butter
pickle jelly and jam jars
heatable film and ood trays
Fiber tote bags clothing film
and sheet ood and beverage
containers carpet strapping
fleece wear luggage and
bottles
(2) PE-HD Stiffness strength
toughness resistance
to chemicals and
moisture permeability
to gas ease o pro-
cessing and ease o
orming
Milk water juice shampoo
dish and laundry detergent
bottles yogurt and margarine
tubs cereal box liners
grocery trash and retail bags
Liquid laundry detergent
shampoo conditioner and
motor oil bottles pipe
buckets crates flower pots
garden edging film and sheet
recycling bins benches dog
houses plastic lumber floor
tiles picnic tables encing
(3) PVC Versatility clarity
ease o blendingstrength toughness
resistance to grease
oil and chemicals
Clear ood and non-ood
packaging medical tubingwire and cable insulation film
and sheet construction pro-
ducts such as pipes fittings
siding floor tiles carpet
backing and window rames
Packaging loose-lea binders
decking paneling guttersmud flaps film and sheet
floor tiles and mats resilient
flooring electrical boxes
cables traffic cones garden
hose mobile home skirting
(4) PE-LD Ease o processing
strength toughness
flexibility ease o
sealing barrier to
moisture
Dry cleaning bread and
rozen ood bags squeezable
bottles e g honey mustard
Shipping envelopes garbage
can liners floor tile urniture
film and sheet compost bins
paneling trash cans land-
scape timber lumber
(5) PP Strength toughnessresistance to heat
chemicals grease and
oil versatile barrier to
moisture
Catsup bottles yogurtcontainers and margarine
tubs medicine bottles
Automobile battery casessignal lights battery cables
brooms brushes ice scrapers
oil unnels bicycle racks
rakes bins pallets sheeting
trays
(6) PS Versatility insulation
clarity easily ormed
Compact disc jackets ood
service applications grocery
store meat trays egg cartons
aspirin bottles cups plates
cutlery
Thermometers light switch
plates thermal insulation egg
cartons vents desk trays
rulers license plate rames
oam packing oam plates
cups utensils
(7) Other Dependent on resin or
combination o resins
Three and five gallon reusable
water bottles some citrus
juice and catsup bottles
Bottles plastic lumber
applications
1 2 3 4 5 6 7
PETE HDPE V LDPE PP PS OTHER
Figure 17 SPI resin identification codes
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 35: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/35.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3538
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 36: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/36.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3638
983089983096 1 Introduction
Table 14 Plastic Bottle Recycling Statistics or 2010 (American Plastics Council)
Plastic bottle type Resin sold (mill Lb) Recycled plastic Recycling rate
PET 5350 1557 291
PE-HD natural 1604 4341 271
PE-HD pigmented 1682 5500 327
Total PE-HD bottles 3286 9841 299
PVC 68 14 20
PE-LD 56 10 19
PP 193 354 183
Total 8953 2579 288
-100
-80
-60
-40
-20
0
POM (MFI0 = 1548)
PC (MFI0 = 210)
PP (MFI0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 029)
Extrusion
Processing event number
( ( M F I 0 -
M F I
F ) M F I 0 ) x 1 0 0
0 1 2 3 4 5
20
40
Figure 18 Change in MFI as a unction o number o extrusion processing events
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 37: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/37.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3738
Problems
1 Determine what material was used to abricate the samples supplied to
you by the instructor
2 An opaque semi-rigid plastic toy with a smooth surace is subjected to a
burn test It does not drip as it burns clean with a blue flame There is a
penetrating smell when the flame is extinguished What material was
used to manuacture this toy Which o the above attributes shouldusually not be taken into account in the decision process
3 A transparent and stiff cup that is involved in a Hamburger-Burger ldquocold
juice spillrdquo lawsuit is given to you by a group o lawyers O the various
materials it could be made o what is your first guess Explain
4 A competitor o yours makes a toy that is opaque stiff and has a smooth
surace You want to know what material it is made o You burn a corner
o the toy The flame is yellow What do you conclude rom your tables
Which one o the attributes can you eliminate to make your decision
easier5 What general type o plastic are you dealing with that does not melt
when heated and remains relatively rigid
-100
-80
-
60
-40
-20
0
20
40
( ( M F I 0 -
M F I F ) M F I 0 ) x 1 0 0
Processing event number
PC (MFI0 = 210)
PP (MFI 0 = 305)
PLA (MFI0 = 1420)
PMMA (MFI0 = 2110)
LDPE (MFI0 = 197)
HDPE (MFI0 = 3780)
Injection
0 1 2 3 4 5
Figure 19 Change in MFI as a unction o number o injection molding processing events
983089983092 Sustainability ndash The 983094th P 983089983097
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)
![Page 38: CH-1Material Science of Polymers for Engineers](https://reader034.vdocument.in/reader034/viewer/2022052607/56d6be591a28ab301691bf7b/html5/thumbnails/38.jpg)
7252019 CH-1Material Science of Polymers for Engineers
httpslidepdfcomreaderfullch-1material-science-of-polymers-for-engineers 3838
983090983088 1 Introduction
6 Write the combustion reaction when burning a PVC sample
7 What material would you select to manuacture saety helmets to be
used in a chemical plant
References
[1] Calhoun A and Peacock A Polymer Chemistry ndash Properties and Applications
Hanser Publishers Munich (2006)
[2] Termonia Y and Smith P High Modulus Polymers A E Zachariades and R S Por-
ter Eds Marcel Dekker Inc New York (1988)[3] Ehrenstein G W Faserverbund-Kunststoffe Hanser Publishers Munich (2006)
[4] Naranjo A Noriega M Osswald T A Roldaacuten A and Sierra J Plastics Testing and
Characterization ndash Industrial Applications Hanser Verlag Muumlnchen (2006)
[5] Saacutenchez K Stoumlckl K Perdomo A and Osswald T A Journal of Plastics Tech-
nology accepted or publication (2012)