F.AShutov

Integral/Structural Polymer Foams Technology, Properties and Applications

Editors: G. Henrici-Olive and S. Olive

English by F. A. Shutov

With 127 Figures and 95 Tables

Springer-Verlag Berlin Heidelberg GmbH

Professor Dr. Fjodor A. Shutov

Mendeleev Institute of Chemistry and Technology, Department of Polymer Processing, Polymer Faculty, Moscow 125820jUSSR

ISBN 978-3-662-02488-1 ISBN 978-3-662-02486-7 (eBook) DOI 10.1007/978-3-662-02486-7

This work is subject to copyright. All rights are reserved, whether the whole or part of the materials is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photocopying machine or similar means, and storage in data banks. Under § 54 of the German Copyright Law where copies are made for other than private use, a fee is payable to the publisher, the amount to "Verwertungsgesellschaft Wort", Munich.

© Springer-Verlag Berlin Heidelberg 1986 Originally published by Springer-Verlag Berlin Heidelberg New York Tokyo in 1986 Softcover reprint ofthe hardcover I st edition 1986

The use of general descriptive names, trademarks, etc. in this publication, even if the former are not especially identified, is not to be taken as a sign that such names, as understood by the Trade Marks and Merchandise Marks Act. may accordingly be used freely by anyone.

Typesetting and Offsetprinting: Th. Miintzer, GDR;

2154/3020-543210

To my beloved parents: Natali and Anatol

Preface

Integral, or structural, foams are one of the most remarkable materials that have been developed over the last fifteen years.

As with all rapidly growing fields, the terminology seems to have grown even faster. Thus there are two names for the material structure itself. In the United States and in Japan the term for these plastics is Structural Foams, whereas in Europe and the USSR the term used is usually Integral Foams. We have adhered to the European term in the text and hope our colleagues will bear with us.

Integral foams have a specific structure: a cellular core that gradually turns into a solid skin. The skin gives the part its form and stiffness, while the cellular core contributes to the very high strength-to-weight values of the material. These are higher than those of some unfoamed plastics and metals.

The sandwich-like structure with its unique mechanical properties was prompted by nature. Wood and bone are strong and light-weight natural materials having a cellular structure.

Since the sandwich-like structure of the integral foams resembles that of natural wood, the foams are often referred to as artifical wood or plastic wood, thereby emphasizing not only the formal structural similarity of these materials, but also one of the main functional applications of integral foams - replacement of wooden articles in various fields of engineering and construction.

There is another very important aspect to the use of foamed plastics. These materials can help resolve two current global crises, i.e. the depletion of non-renewable organic raw materials (oil and gas) and the energy crisis. Foamed plastics use less polymer (than unfoamed plastics) because a considerable part of the volume is plastics taken up by a gas (air). As to the energy crisis, the cellular structure produces a very low thermal conductivity making foamed excellent thermal insulators.

It is the physics of manufacturing these materials that is unique. Indeed, the integral structure is created by the interplay of the main physical parameters - temperature and pressure - on the foaming polymer melts or solutions. This is why I have devoted a considerable portion of the book to a discussion of the technology and equipment of integral foams and to an analysis of the optimum processing parameters.

This book covers in detail the fundamental correlations between the morphology and properties of integral foams and the formulation, equipment, and processing parameters.

Various applications of the products are discussed together with a review of the design and marketing problems. In addition, I have included an economic analysis of the commercial processes, for most of the materials.

I have tried to write a book that will be useful for:

chemists and physicists, who create the integral foams, technologists and engineers, who manufacture them, consumers and managers, who apply these plastics, and

Preface

students and post-graduates, who study the science, technology and applications of polymer materials.

I tried to write not just a scientific monograph, but a manual and handbook as well.

The references are surveyed trough Summer 1985. I should be extremely grateful for any comments or criticism you may care to

send me.

Moscow, July 1985 Fyodor A. Shutov

Acknowledgements

Scientists from many countries have been "invisible" coauthors to this book, for it is their efforts that have resulted in the remarkable scientific and practical developments in the field of integral foamed plastics. I would like to express my deep gratitude to my colleagues in different countries who kindly took part in the discussions of this manuscript, or sent me copies of their papers and reports.

I have the pleasure to acknowledge the contributions of the following workers in the field:

Argentina: R. J. J. Williams; Austria: L. Golser, H. Hubeny, P. J. Schmidt; Belgium: J. L. Lambert, P. Stachel, R. H. Young; Bulgaria: N. Popov, S. Semerdjiev; Canada: C. C. Elliott; England: G. E. Anderton, R. H. Burton, K. T. Collington, P. R. Hornsly, D. R.

Moore, G. Woods; France: Ch. Bonfillon, P. Jentet; Federal Republic of Germany: H.-J. Barth, A. Bauer, W. Becker, G. Blay, F. L.

Boschke, H. Borger, H. Eckardt, V. Faroga, H. Hauf, J. Harting, W. Kleber, A. Malburg, G. Menges, H. Miiller, U. Osinski, K. Pontius, H. Reichstein, H. Sadlon, R. Schaffrath, E. Schirlbauer, K. Schluter, E. Zahn, H. Zehender;

Holland: G. Hesse, P. Salwiczek; Italy: C. Fiorentini, L. Nicolais, O. Orlandi, R. Pernice; Japan: K. Ashida, H. Okamoto, Y. Oyanagi; Mexico: A. Rios Sanchez; Switzerland: B. Baumberger, G. H. Hull, J. P. Sormani, A. Sternfield, W. K. Veith; USA: J. Ahnemiller, M. Amon, R. G. Angell, E. W. Archer, W. E. Becker, D. L.

Bernard,-W. R. Burk, N. Chessin, M. Cook, R. Drake, J. A. Gribens, C. D. Han, G. T. Harrick, R. L. Heck, V. Herbert, S. Hettinga, S. Hobbs, E. Hunerberg, J. Klemm, D. L. Leis, L. T. Luft, R. J. Manno, G. L. Nelson, F. R. Nissel, R. C. Progel­hof, D. Reithoffer, C. Rosis, M. Rubenstein, D. L. Smith, C. D. Storms, P. M. Thomas, J. L. Throne, H. P. Torner, C. S. Wang, B. C. Wendle, A. C. Werner, J. E. Widdel, and M. G. Wilson.

lowe thanks to my colleagues from the USSR who kindly agreed to look through various chapters of this manuscript and who came up with many useful remarks and comments; they are: I. Chaikin, Yu. Esipov, G. Kusmin, Yu. Lozhechko, and A. Zukerman.

Nevertheless, my main coauthor has been my loving, devoted and understanding wife Helena, whose faith in my work has been constant.

Table of Contents

Abbreviations. . . . . . . . . . . . . . . . . . . . . . . . . . . . . XIX

Section A: General Information

1 General Description of Integral (Structural) Foams 1.1 Definition ofIntegral Foam l.2 Terminology.. . . . . . . . . 1.3 Distinctive Properties . . . . . . 1.4 Comparison with Other Materials . 1.4.1 Integral Foam versus Wood ... 1.4.2 Integral Foam versus Unfoamed Plastics 1.4.3 Integral Foam versus Metals . 1.4.4 Integral Foam versus Concrete 1.4.5 General Comparison 1.5 Classification. l.6 References....

2 Starting Materials. . . . . . . . . . 2.1 High Polymers and Reactive Oligomers 2.2 Blowing Agents. . . . . 2.3 Physical Blowing Agents . 2.4 Chemical Blowing Agents 2.4.1 Types of Agent. . ... . 2.4.2 Forms of Agents . . . . 2.5 Effect of Blowing Agents. 2.5.1 Density ..... 2.5.2 Cellular Structure. 2.5.3 Shrinkage . . . 2.5.4 Surface Quality. . 2.5.5 Cooling Time. . . 2.6 Nucleating Agents 2.7 Other Additives. . 2.7.1 Types of Additives 2.7.2 Fillers and Reinforcing Agents 2.7.3 Pigments .. 2.8 References.........

3 3 5 6 7 8 9 9 9

10 11 11

13 13 13 14 15 15 17 19 19 20 21 22 22 23 23 23 24 24 25

XII

Section B: Integral Polymer Foam Technology

3 Injection Molding: General 3.1 Classification...... 3.2 Basic Principle . . . . . 3.3 Basic Commercial Processes 3.4 Machines . . . . . . 3.4.l General Considerations 3.4.2 Types of Machines 3.5 Molds ..... 3.5.l Mold Materials. 3.5.2 Mold Design. 3.5.3 Mold Filling 3.5.4 Demolding. . 3.5.5 Venting . . . 3.5.6 Hot Runner Systems 3.5.7 Problems . . . 3.6 Cooling Process. 3.6.1 Cooling Time. 3.6.2 Cooling Units 3.6.3 Problems . 3.7 References ..

4 Injection Molding: Low Pressure Process 4.1 Basic Process. . . . . 4.2 Commercial Processes. . . 4.2.1 The UCC Process ..... 4.2.2 The TCM-Hettinga Process. 4.2.3 Other Processes. . . . . 4.3 Equipment Specifications 4.3.1 Injection Units . . . . . 4.3.2 Clamping Units. . . . . 4.3.3 Single- and Multi-Nozzle Systems. 4.3.4 Recent Developments 4.4 References.. . . . . . . . . .

5 Injection Molding: High Pressure Process . 5.1 Basic Process. . . . . 5.2 Commercial Processes. 5.2.1 The USM Process ... 5.2.2 The Dow-TAF Process 5.3 Equipment Specifications 5.4 Technical and Economic Analysis. 5.5 References...........

6 Injection Molding: Gas Counter Pressure Process. 6.1 Basic Process. . . . . 6.2 Commercial Processes. . . . . . . . . . . .

Table of Contents

29 29 29 29 32 32 33 36 36 37 39 40 40 41 42 43 43 44 44 45

47 47 48 48 49 51 51 51 52 54 56 58

59 59 61 61 61 64 65 69

71 71 71

Table of Contents

6.2.1 The Allied Processes 6.2.2 The TM Process . . 6.2.3 The Asahi-Dow Process 6.2.4 Other Processes. . . . 6.3 Equipment Specifications 6.4 Technical and Economic Analysis . 6.5 References...........

7 Injection Molding: Two Component Process . 7.1 Process in General 7.1.1 Basic Process. . . . . 7.1.2 Starting Materials. . . 7.1.3 Compatibility Problem. 7.1.4 Density Problem ... 7.2 Commercial Processes. 7.2.1 The ICI and BB Processes 7.2.2 The Injection Mixing Process. 7.2.3 Other Processes. . . . . 7.3 Equipment Specifications 7.3.1 Machines . . 7.3.2 Injection Units . . . . . 7.3.3 Molds. . . . . . . . . 7.4 Technical and Economic Analysis. 7.5 References...........

8 Reaction Injection Molding Process. 8.1 Introduction....... 8.2 Terminology and Definitions 8.3 Basic Process. . . . . . 8.4 Equipment Specifications 8.4.1 Metering Units . 8.4.2 Mixing Heads 8.4.3 Molds. . . . 8.4.4 Mold Filling . 8.4.5 Mold Tooling 8.4.6 Clamping Units. 8.5 Technical and Economic Analysis . 8.5.1 RIM versus Other Polyurethane Processes 8.5.2 RIM versus Thermoplastic Processes. 8.5.3 RIM and Energy Saving 8.5.4 Current Trends. 8.6 References.

9 Extrusion. 9.1 Basic Process. 9.1.1 Free and Control Extrusion Processes 9.1.2 Practical Realization . . . . . . .

XIII

71 73 75 76 78 78 80

81 81 81 81 82 84 84 84 86 87 87 87 89 90 90 91

92 92 93 94 96 97 98 99

100 102 103 104 104 106 107 108 109

111 111 111 112

XIV

9.2 Commercial Processes. 9.2.1 The Celuka Process . 9.2.2 Coextrusion Process. . 9.2.3 Other Processes. . . . 9.3 Equipment Specifications 9.4 Technical and Economic Analysis. 9.5 References...........

10 Rotational Molding and Other Processes 10.1 Rotational Molding Process . . . . . 10.1.1 Basic Process ........... . 10.2 Commercial Rotational Molding Processes 10.2.1 The Uniroyal Process . . 10.2.2 The Borg-Warner Process .... 10.2.3 Other Processes. . . . . . . . . 10.2.4 Technical and Economic Analysis . 10.3 Free-Foaming Process. . . . 10.4 Conventional Molding Process 10.5 References......

11 Secondary Processing . 11.1 Pre-Molding Processes. 11.2 Post-Molding Processes 11.2.1 Training. . . . . . . 11.2.2 Painting and Coating . 11.2.3 Modification of Properties 11.2.4 Electromagnetic Interference Shielding . 11.3 Pseudo-Integral Polymer Foams .. 11.4 Technical and Economic Analysis. . . 11.5 References.............

12 Comparison and Selection of Integral Foam Processes . 12.1 Comparison of Processes . 12.1.1 Process Parameters 12.1.2 Density Reductions . 12.1.3 Surface Roughness . 12.1.4 Process Cost Analysis 12.2 Selection of Processes 12.2.1 Dimensions and Weight of Parts 12.2.2 Number of Parts . . . . . . . 12.2.3 Single/Multi Cavity Alternative . 12.2.4 Single/Multi Nozzle Alternative. 12.3 References..........

Section C: Integral Polymer Foam Practice

13 Integral Foam Based on Polyurethanes 13.1 Raw Material Specifications 13.1.1 Polyols and Isocyanates ..... .

Table of Contents

113 113 116 118 120 121 122

123 123 123 124 124 127 127 128 129 129 130

131 131 131 131 132 134 134 134 135 136

138 138 138 138 141 143 146 146 146 147 148 149

153 153 153

Table of Contents

13.1.2 Blowing Agents. 13. I.3 RIM Parts. . . 13.1.4 PRIM Parts . . 13.2 Processing Parameters Specifications. 13.2.1 Molding Time . . . 13.2.2 Molding Temperature 13.2.3 Skin Density. . . . 13.2.4 Molding Pressure. . 13.2.5 Selection of Optimal Parameters 13.2.6 Practical Recommendations 13.3 Properties.... 13.3.1 Strength Properties 13.3.2 Thermal Shrinkage 13.3.3 Thermal Expansion 13.3.4 Thermal Stability . 13.3.5 Light and Color Stability. 13.3.6 Dielectric Properties. . . 13.3.7 Other Properties .... 13.4 Application of Rigid Parts 13.4.1 Construction Industry . 13.4.2 Furniture . . . . . . . 13.4.3 Office Equipment. . . . 13.4.4 Audio and TV Equipment 13.4.5 Electrical Industry 13.4.6 Sports Equipment. 13.4.7 Sanitary Fixtures . 13.4.8 Other Applications 13.5 Applications of Flexible Parts. 13.5.1 Passenger Cars ... 13.5.2 Vans and Trucks . . . . . . 13.5.3 Two-Wheel Industry. . . . . 13.5.4 Prospects in Automotive Industry. 13.5.5 Shoe Soles Industry. . . . . . . 13.5.6 Other Applications . . . . . . . 13.6 Technical and Economic Analysis. 13.6.1 PUR versus PS Integral Foams . . 13.6.2 RIM Foams versus Other Materials 13.6.3 Non-RIM versus RIM Foams 13.7 References...........

14 Integral Foam Based on Polystyrene 14.1 Technology Specifications 14.2 Commercial Processes. 14.2.1 Injection Molding. 14.2.2 Extrusion . . . 14.2.3 Other Processes. 14.3 Properties...

xv

155 156 157 158 158 159 160 161 162 166 166 167 172 175 176 176 177 178 178 179 179 179 180 180 180 180 180 180 181 181 181 182 182 183 183 183 183 186 187

189 189 190 190 192 193 193

XVI

14.3.1 Mechanical Properties. 14.3.2 Other Properties . . . 14.4 Applications.. . . . 14.5 Technical and Economic Analysis. 14.6 References...........

15 Integral Foam Based on Poly(vinyl chloride) 15.1 Technology Specifications 15.2 Commercial Processes. 15.3 Properties....... 15.4 Applications.. . . . . 15.5 Technical and Economic Analysis. 15.6 References .......... .

16 Integral Foam Based on Polyolefins 16.1 Technology Specifications 16.l.l Injection Molding. 16.l.2 Extrusion . 16.2 Properties. . . . 16.3 Applications.. . 16.4 Technical and Economic Analysis. 16.5 References...........

17 Integral Foam Based on ABS-Copolymers . 17.1 Technology Specifications 17.2 Properties. . . . 17.2.1 Molding Parts .. 17.2.2 Coextruded Sheets 17.2.3 Co extruded Pipes . 17.3 Applications... 17.4 Technical and Economic Analysis . 17.5 References .......... .

18 Integral Foam Based on Polyphenylene Oxide 18.l Raw Material Specifications 18.l.l Blowing Agents. . . . 18.l.2 Freon Ecology Problem 18.2 Properties. 18.3 Applications 18.4 References.

19 Integral Foam Based on Polycarbonates. 19.1 Technology Specifications 19.2 Properties. 19.3 Applications 19.4 References.

Table of Contents

193 196 197 198 200

202 202 203 205 207 208 209

211 211 211 212 213 215 217 217

219 219 220 220 222 223 223 224 225

227 227 227 228 228 230 231

232 232 233 235 236

Table of Contents

20 Other Types of Integral Foams 20.1 Polyamide...... 20.2 Thermoplastic Polyester 20.3 Polyacetal.. 20.4 Polyimide. . . 20.5 Epoxy Resins. . 20.6 Phenolic Resins. 20.7 Other ... 20.8 References...

Section D: Calculation, Design and Marketing Fundamentals

21 Calculation of Strength and Other Properties . . . 21.1 Basic Morphological Parameters ofIntegral Foams 21.1.1 Apparent Density ....... . 21.1.2 Density Distribution. . . . . . . 21.2 Calculation of Strength Properties. 21.2.1 Problems . . . . . . 21.2.2 Semerdjiev's Approach 21.2.3 Gonzalez's Approach 21.2.4 Hartsock's Approach 21.2.5 Hobbs's Approach . 21.2.6 Throne's Approach . 21.2.7 Other Calculation Formulas 21.3 Calculation of Thermal Conductivity 21.4 Further Problems . 21.5 References...

22 Design Concepts 22.1 Design Possibilities 22.2 Thin-Wall Integral Foams 22.3 Wall-Thickness Selection. 22.4 Polymer Type Selection 22.5 Design Criteria . 22.6 References......

23 Current and Future Trends 23.1 Industry Position of Integral Polymer Foam 23.2 Marketing Position of Integral Polymer Foam. 23.3 References..........

Firms, Firm-Processes and Grades Index

Subject Index. . . . . . . . . . . .

XVII

237 237 237 238 239 239 239 240 240

245 245 245 246 247 247 248 249 251 251 253 255 257 258 259

260 260 260 262 264 264 264

265 265 267 270

271

275

Abbreviations

ABS ACA BA BMC CBA CCIM CFE CIM CTE DMCHA DMEA DNPMTA DUDEG DWV EMI EMT ESD FFE FR FRP GCP GSE HOPE HF HIPS HM HP HPE HPIM HV IF 1M IM-HP IM-LP IPN LIM LRIM

Acrylonitrile-butadiene-styrene copolymer Azodicarbonamide Blowing agent Bulk molding compound Chemical blowing agent Counter-current impingement mixing Controlled foam extrusion Conventional injection molding Coefficient of thermal expansion Dimethylcyclohexylamine Dimethylethanolamine Dini trosopentamethylenetetramine Diurethane-diethylene glycol Drain, waste and vent pipe Electromagnetic interference plastic Electromagnetic transparent plastic Electrostatic discharge (dissipative) effect Free foaming extrusion Fire-resistant material Fiber reinforced plastic Gas counter pressure process Gas-structural element High-density polyethylene High-frequency heating element High-impact polystyrene High modulus material High pressure process High performance elastomeric material High pressure impingement mixing High velocity process Integral foam Injection molding High pressure injection molding Low pressure injection molding Interpenetrating polymer network Liquid injection molding Liquid reaction injection molding

xx

LP LPF LRM MDI MMD PA PAPI PBA PBE PBT PC PE PF PIC PMMA PO PP PPMS PPO PS PUR PVA PVC RFI RIM RRIM RSG SAN SF SIN SMC SW TCF TCM TDI TEA TEC TSG UV

Low pressure process Low pressure foaming Liquid reaction molding Methylene-diisocyanate Molecular mass distribution Polyamide Polymethylene-polyphenylisocyanate Physical blowing agent Private branch exchange Poly-(butylene terephthalate) Polycarbonate Polyethylene Phenol-formaldehyde resin Polyisocyanate Poly(methyl methacrylate) Polyolefin Polypropylene Poly-para-methylstyrene Poly(phenylene oxide) Polystyrene Polyurethane Poly(vinyl alcohol) Poly(vinyl chloride) Radio frequency interference plastic Reaction injection molding Reinforced reaction injection molding Reaction "Schaum Guss" Styrene-acrylonitrile copolymer Structural foam Simultaneous interpenetrating network Sheet molding compound Structural web Two component foam Thermoplastic cellular molding process Tolylene diisocyanate Triethylamine Thermal expansion coefficient Thermoplast "Schaum Guss" Ultraviolet

Chemical and Physical Symbols

A coefficient; width; work B coefficient; thickness C concentration; shape factor d, D diameter D diffusion coefficient D Q density gradient

Abbreviations

Abbreviations XXI

E elasticity modulus Eo modulus of unfoamed polymer Ee compression modulus; core modulus Eds dielectric strength Ef flexural modulus Es skin modulus Et tensile modulus G shear modulus H hardness; roughness; thickness I moment of inertia Ii isocyanate index k Boltzmann constant; solubility coefficient K curvature; foaming coefficient KF Fikentscher constant L length; coefficient LID length-to-diameter ratio n,N coefficients nOH hydroxyl group concentration N Avogadro number p pressure; weight Q shear force r radius; 8Jo. R gas constant Sy static moment S surface area tgex. dielectric losses (dissipation factor) T reduced moment of inertia; temperature; tight

Tdee decomposition temperature Tm maximum temperature; molding temperature

Tmold molding temperature W moment of resistance; width x distance y deflection; distance; height Z distance ex. angle; coefficient of thermal expansion 8 thickness 8. article thickness 8e core thickness 8iz intermediate zone thickness 'Os skin thickness E dielectric constant; deformation 3p volume fraction of polymer phase x shrinkage Xs surface resistance Xv volume resistance A thermal conductivity; wave length Ao thermal conductivity of air

XXII Abbreviations

Ag thermal conductivity of gas Ap thermal conductivity of unfoamed polymer v Poisson number Q density; apparent density; specific density; local density; volume weight Qo density of umfoamed polymer Q. article density Qc core density Qrn overall density Qp density of unfoamed polymer Qr relative density Qs skin density Qst density of structure ~Q differential density a strength; surface tension a c compressive strength; core strength a f flexural strength a p strength of un foamed polymer at tensile strength a tr tearing strength , time; cycle 'c cooling time 'd dwelling (molding) time '<p conversion period <P degree of conversion <PQ integral density distribution

Units Conversion Chart Length

Area

Volume

Density Mass Force Strength/Modulus

Pressure

Thermal Conductivity

Heat Quantity Dynamic Viscosity Temperature

Imm 1m

= 0.0394 in = 3.2808 ft

1 mm2 = 0.0016 sq in 1 m2 = 10.764 sq ft 1 m3 = 35.3144 ft3

1 I = 0.26417 gal 1 kg/m3 = 0.0624 pcf 1 kg = 2.2046 Ib 1 kg = 9.80665 N ~ 10 N I kg/cm2 = 0.0981 N/mm2 ~ 0.1 N/mm I MPa = 1 N/mm2 1 MPa = 145 psi I at = 1 kg/cm2 = 0.9806 bar ~ 1 bar 1 Pa = 10- 5 bar 1 W/Km = 0.86 kcal/m hOC 1 W/Km = 0.579 BTU/ft h of 1 W /Km = 6.95 BTU in/ft2 h 1 kcal = 4.187 kJ 1 cP = I mPa· s of = °C . 1.8 + 32