seminar 2 smps final

Shape Memory Polymers

PRAJESH KUMAR JHA

2ND SEM, M.E.(AMT)

10 GAMB 4009

Contents: ---

INTRODUCTION SHAPE MEMORY EFFECT POLYMERS SHAPE MEMORY POLYMERS THERMALLY INDUCED SMPs LIGHT INDUCED SMPs ELECTRO ACTIVE SMPs SMPs Vs. SHAPE MEMORY ALLOYS APPLICATIONS OF SMPs CONCLUSION REFERENCES

PRAJESH KUMAR JHA SEMINAR-II2

SHAPE MEMORY POLYMERSINTRODUCTION

Introduced to United States in 1984 after its original introduction in Japan.

Combination of Polymeric materials with the capability to temporarily deform then restore to their original shape through thermal stimuli such as temperature change.

Exhibit long covalent cross linked bonds. Tested to potentially deform up to 200% of

their original state and still restore their original shape.

Light weight Potentially biodegradable for surgical

procedures Cheaper to manufacture than Shape

memory Alloys.


Technology – Shape-Memory Effect

RecoveryProgramming

permanentshape temporary

shape

permanentshape


POLYMERS

A polymer is a large molecule composed of repeating structural units typically connected by covalent chemical bonds.

THEROPLASTICSTHERMOSETSELASTOMERS


Different types of Polymers

LOW DENSITYHIGH DENSITY


SHAPE MEMORY POLYMER DEFINITIONSMPs are polymeric smart materials which have the ability to return from a deformed state (temporary shape) to their original (permanent) shape induced by an external stimulus

Triggers– Temperature– pH– Light– Magnetic or electric field

Two properties:– Strain recovery rate (Rr)

– Strain fixity rate (Rf).

The strain recovery rate describes the ability of the material to memorize its permanent shape, while the strain fixity rate describes the ability of switching segments to fix the mechanical deformation.


THERMALLY INDUCED SMPs

STIMULUS TRIGGER: --- PROGRAMMED HEATING CHANGE IN MOLECULAR NETWORK STRUCTURE TWO VISIBLE FORMS: --- a.) TEMPORARY FORM

b.) PERMANENT FORM THE POLYMER MAINTAINS THIS TEMPORARY SHAPE

UNTIL THE SHAPE CHANGE INTO THE PERMANENT FORM IS ACTIVATED BY A PREDETERMINED EXTERNAL STIMULUS.

SHAPE MEMORY POLYMERS ARE EFFECTIVELY VISCOELASTIC AND MANY MODELS AND ANALYSIS METHODS EXIST


THERMODYNAMICS OF THE SHAPE MEMORY EFFECT

In the amorphous state, polymer chains assume a completely random distribution within the matrix.

In the transition from the glassy state to a rubber-elastic state by thermal activation, the rotations around segment bonds become increasingly unimpeded.

As a result, the majority of SMPs will form compact, random coils because this conformation is entropically favored over a stretched conformation.

Polymers in this elastic state, with number average molecular weight greater than 20,000 stretch in the direction of an applied external force.


THERMODYNAMICS OF THE SHAPE MEMORY EFFECT

If the force is applied for a short time, the entanglement of polymer chains with their neighbours will prevent large movement of the chain and the sample recovers its original conformation upon removal of the force.

If the force is applied for a longer period of time, however, a relaxation process takes place whereby a plastic, irreversible deformation of the sample takes place due to the slipping and disentangling of the polymer chains.

To prevent the slipping and flow of polymer chains, cross-linking can be used, both chemical and physical.


PHYSICAL CROSSLINKED SMPs

LINEAR BLOCK COPOLYMERS :--- Polyurethanes Polyethylene terephthalate Polyethylene oxide (PEO)

OTHER THERMOPLASTIC POLYMERS Amorphous polynorbornene Polyhedral oligosilsesquioxane (POSS)


CHEMICALLY CROSSLINKED SMPs

CROSSLINKED POLYURETHANE Disocyanate trimethylol propane

PEO BASED CROSSLINKED SMPS Ethylene glycol dimethacrylate N,N'-methylene-bis-acrylamide

THERMOPLASTIC SHAPE-MEMORY PEEK


LIGHT INDUCED SMPs

LIGHT ACTIVE SMPs ARE USED

STIMULUS TRIGGER: --- LIGHT OF DIFFERENT FREQUENCIES

MECHANISM: --- BY PHOTO-CROSSLINKING & PHOTO-CLEAVING MATERIAL SWITCHES BETWEEN ELASTOMERS & RIGID POLYMERS DUE TO CHANGE

IN CROSSLINKING DENSITY

Polymers containing cinnamic groups can be fixed into predetermined shapes by UV light illumination (> 260 nm) and then recover their original shape when exposed to UV light of a different wavelength (< 260 nm).


ELECTRO ACTIVE SMPs

Used in conducting SMPs composites with MWNTs, Metals, Short Carbon Fibers

Stimulus Trigger: -- Electricity Used where heating is restricted Remote actuation is possible by using SMPs

composites having super paramagnetic materials Example: --oligo (e-capolactone) dimethacrylate/butyl

acrylate composite with between 2 and 12% magnetic nanoparticles.


SMPs Vs. SHAPE MEMORY ALLOYS

DIFFERENCES BETWEEN SMPs AND SMAsPROPERTIES SMPs SMAs

Density (g/cm3) 0.9–1.1 6–8

Extent ofdeformation

up to 800% <8%

Required stressfor deformation (MPa)

1–3 50–200

Stress generatedupon recovery (MPa)

1–3 150–300

Transitiontemperatures (°C)

–10..100 –10..100

Recovery speed1s –

minutes<1s

Processingconditions

<200 °C lowpressure

>1000 °C highpressure

Costs

<$10/lb ~$250/lb


Applications

Self Deployment Mechanisms

Eyeglass Frames Automatic auto body

repairs. Reusable Molds. Custom reusable

mandrels.


Anticipated Applications

Biodegradable biomedical stems.

Artificial muscles Aeronautical Morphing

Wings Outer Space self

deployment systems Self stitching

biodegradable materials


APPLICATIONS OF SMPs

INDUSTRIAL APPLICATIONS

MEDICAL APPLICATIONS

POTENTIAL MEDICAL APPLICATIONS

POTENTIAL INDUSTRIAL APPLICATIONS

OTHER POTENTIAL APPLICATIONS


SHAPE MEMORY APPLICATIONS – PRESENT TRENDS

Shower springs that are activated above a certain temperature to shut off water that is too hot.

Window latches that open and close automatically to protect plants in a nursery

Eyeglass frames that recover their original shape when accidently bent out of shape

Blood clot filters that when inserted into the body open up at body temperature to arrest clots

Bracing wires to straighten teeth


SHAPE MEMORY APPLICATIONS –PRESENT TRENDS

Rods connected to spines to correct/ straighten it Actuators for vanes controlling the flow of air through

jet engines Devices to control the sag of electrical power

transmission lines Circuit boards that disconnect from mother boards

easily for repair or replacements Cryofit couplings that can be used to repair broken fuel

or oil lines in an emergency


CONCLUSION

THE SHAPE MEMORY POLYMERS ARE A NEW CLASS OF ENGINEERING MATERIALS, WHICH HAS A LOT SCOPE FOR IMPLEMENTATIONS IN THE SEVERAL SMART STRUCTURES AND A TREMENDOS HOPE FOR UNSOLVED CRITICAL DESIGN PROBLEMS INVOLVING A REQUIREMENT OF THE FANTASTIC SHAPE MEMORY EFFECTS.

WHEREEVER THERE IS A PLACE FOR TRAINABILITY AND MEMORY ASPECTS IN THE ENGINEERING ENGINEERED DESIGN STRUCTURES OR ELEMENTS, THE SHAPE MEMORY POLYMERS WILL BE A BOON FOR THE INNOVATIVE PROFESSIONALS TO CREAT WONDERS AND SO ALMOST INEVITABLE FOR COSIDERATIONS.

. PRAJESH KUMAR JHA

SEMINAR-II21

References

Srinivasan A.V. and McFarland Michael D. (2001), Smart Structures – analysis and design, Cambridge University Press.

Raymond A. Higgins (2006), Materials for Engineers and Technicians, Elsevier. Kenneth G. Budinski and Michael K. Budinski (2009), Engineering Materials –

Properties and Selection, PHI Learning Private Limited. Shivanand H.K. and Babu Kiran B.V. (2010), Composite Materials, Asian Books

Private Limited. http://en.wikipedia.org/wiki/Shape_memory_polymer Jorge Ramos, Shape Memory Polymers, Cornerstone Research Group ,

( http://crgrp.net) Tesfaberhan Habtemariam, Omid Borjian and Elena Foster (2009), Polymers,

Santa Rosa Junior College.


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