Shape memory performance of epoxy resin based composites
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Shape Memory Performance of Epoxy Resin-Based Composites. József Karger-Kocsis , Márta Fejős Budapest University of Technology and Economics Department of Polymer Engineering E-Mail: [email protected] Outline. Introduction Motivation Possible applications Properties of shape memory epoxy

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Shape Memory Performance of Epoxy Resin-Based Composites

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Shape memory performance of epoxy resin based composites

Shape Memory Performance of Epoxy Resin-Based Composites

József Karger-Kocsis, Márta Fejős

Budapest University of Technology and Economics

Department of Polymer Engineering

E-Mail: [email protected]


Shape memory performance of epoxy resin based composites

Outline

  • Introduction

  • Motivation

  • Possible applications

  • Properties of shape memory epoxy

  • Properties of shape memory epoxy composites

  • Future works


Shape memory performance of epoxy resin based composites

Introduction

Materials

Non linear,

Reversible

Material’s property

Functionalmaterials

Structuralmaterials

Ttrans

Smart materials

Smartmaterials

Environmental condition

(Temperature)

Shapememorymaterials

Shapememoryalloys

Shapememorypolymers

20°C


Shape memory performance of epoxy resin based composites

Extension

and

cooling

shape B

Ttrans

shape A

Ttrans

Heating

Ttrans

shape B

netpoint

Switching segment, relaxed

Switching segment, elongated and fixed

Molecular Mechanisms of Thermally-Induced Shape-Memory Effect

M. Behl and A. Lendlein: materialstoday, 10 (2007), No.4, 20-28


Shape memory performance of epoxy resin based composites

Schematic Architecture of SMPs

J. Hu, Y. Zhu, H. Huang and J.Lu. Progr.Polym.Sci. 37 (2012), 1720


Shape memory performance of epoxy resin based composites

Basic Differences Between SMA and SMP

P. Ghosh et al.: Mater. Design 44 (2013), 164-171


Shape memory performance of epoxy resin based composites

Motivation

  • Toincreaserecoverystresswithoutloosingthe

  • deformability

  • Attemptswithepoxyresin-basedcomposites


Shape memory performance of epoxy resin based composites

Shape Memory Epoxy Resin – Mechanism and Properties

T<Tg

T>Tg

T<Tg

T>Tg after T<Tg

Ttrans=Tg

  • Excellent shape fixity and shape recovery properties (>95% each)

  • Good environmental durability (essential for space applications)

  • Good adhesive properties (matrix material in polymeric composites)


Shape memory performance of epoxy resin based composites

Property Tailoring with Epoxy Resins

Storage modulus [MPa]

Temperature [°C]


Shape memory performance of epoxy resin based composites

Possible Applications of Shape Memory Epoxy Composites

Solar array

Deployable space structures

Reflector

J. Lenget al.: Progress in Material Science56 (2011), 1077-1126


Shape memory performance of epoxy resin based composites

Shape Memory Properties - Unconstrained (Free) Recovery

Rf [%] shape fixity ratio

Rr [%] shape recovery ratio

RΣ [%] shape memory ratio

ε0 [%] original shape

εm [%] required temporary shape

εu [%] fixed temporary shape

εp[%] recovered shape

Ts [°C] storage temperature

Tg [°C] glass transition temp.

Td [°C] deformation temp.

σmin [MPa] preload stress

σload[MPa] deformation stress

εm

Td

εu

Strain, ε [%]

Temperature, T [°C]

Tg

Rf

Rr

εp

Stress, σ [MPa]

σfix

σload

Ts

σmin

Time, t [min]

ε0

  • Temperature, stress and strainas a function of time

    • Universaltensiletester

    • Dynamicmechanicalanalyser

  • Deformationmodes:

    • Tensionorcompression

    • Flexure

    • Torsion


Shape memory performance of epoxy resin based composites

Shape Memory Properties - Constrained Reheating

εm

ε0 [%] original shape

εm [%] required temporary shape

Ts [°C] storage temperature

Tg [°C] glass transition temp.

Td [°C] deformation temperature

σmin [MPa] preload stress

σload[MPa] deformation stress

σrec[MPa] recovery stress

Td

Strain, ε [%]

Temperature, T [°C]

Tg

Stress, σ [MPa]

σfix

σload

σrec

Ts

σmin

Time, t [min]

ε0

  • Recovery stress determined in fully constrained reheating

  • Recovery stress is equal to the deformation stress, if no damage occurred in the specimen. Therefore recovery stress can be estimated from „traditional” unconstrained tests, if stress is measured.


Shape memory performance of epoxy resin based composites

Shape Memory Performance of Epoxy/Glass Fiber Fabric Composite

  • Strain at break [%]

    • E-Glass fibre~2.5

    • Carbon fibre~1.6

    • Aramid fibre~3.5

    • Flax fibre~2.9

2

3

4

4

3

2

1

1

1

2

3

4

Deformation

Fixation

Recovery

Unload

M. Fejős, G. Romhány, J. Karger-Kocsis: Journal of Reinforced Plastics and Composites 56 (2012), 1532-1537


Shape memory performance of epoxy resin based composites

Asymmetric Shape Memory Epoxy/Carbon Fiber Fabric Composites

  • Carbon fibre has negative thermal expansion coefficient, which increases the asymmetry

  • Asymmetric samples show buckling upon temperature change, because of the different thermal expansion coefficient of the layers.

M. Fejős, J. Karger-Kocsis: Express Polymer Letters 7 (2013), 528-534


Shape memory performance of epoxy resin based composites

Asymmetric Shape Memory Epoxy/Carbon Fiber Fabric Composites – Unconstrained Shape Memory Test

EPCF2t

EPCF2b

σ control

εcontrol

σ control

ε control

Based on bending test: εm=2.5%

M. Fejős, J. Karger-Kocsis: Express Polymer Letters 7 (2013), 528-534


Shape memory performance of epoxy resin based composites

Asymmetric Shape Memory Epoxy/Carbon Fiber Fabric Composites – Constrained Shape Memory Test

EPCF2b

EPCF2t

M. Fejős, J. Karger-Kocsis: Express Polymer Letters 7(2013), 528-534


Shape memory performance of epoxy resin based composites

ELO Based Flax Fiber Fabric-Reinforced Biocomposites

Twill (T) 420 g/m2

Nonwoven (NW) 220 g/m2

Quasi UD 420 g/m2

Quasi UD 275 g/m2

  • Matrix: epoxidized linseed oil (ELO) cured by stoichiometric amount of methyltetrahydrophthalic anhydride (Aradur 917 CH), accelerated by 1-methylimidazole (both from Huntsman Advanced Materials).

  • Textile conditioning: Drying at least 3 hours at 80°C, prompt impregnation.

  • Applied pressure and temperatures: 8 MPa; 2h 100°C, 2h 140°C and 2h 180°C.

:

M. Fejős, S. Grishchuk, J. Karger-Kocsis: Journal of Reinforced Plastics and Composites 32 (2013), 1879-1886


Shape memory performance of epoxy resin based composites

ELO Based Flax Fiber Fabric-Reinforced Biocomposites - DMTA

  • The higher the fiber content the lower is the Tg, because remaining water and

  • hydroxil groups react with anhydride hardener.

M. Fejős, S. Grishchuk, J. Karger-Kocsis: Journal of Reinforced Plastics and Composites 32 (2013), 1879-1886


Shape memory performance of epoxy resin based composites

ELO/Flax Fiber Textile - Reinforced Biocomposites

– Shape Memory Behavior

Deformation

1

Fixation

2

Unload

3

Recovery

4


Shape memory performance of epoxy resin based composites

ELO Based Flax Fiber Fabric-Reinforced Biocomposites – Shape Memory Performance

  • Naturalfiberslowernotonlytheshapefixity, butalsotheshaperecoveryratios (discontinuousfiber, fiber/matrixinterphase)

  • ELO matrix is „weak” (lowcrosslinkdensity)

M. Fejős, S. Grishchuk, J. Karger-Kocsis: Journal of Reinforced Plastics and Composites 32 (2013), 1879-1886


Shape memory performance of epoxy resin based composites

Summary

  • Reinforcements reducethe„shaping freedom”.

  • Damage starts at the compression side of the specimen in flexure, but microbuckling can be exploited for shape memory.

  • Asymmetrical reinforcement may support the shape memory if suitable fibers are positioned at the tension side of the specimen.

  • Shape memory strain and recovery stress can be simultaneously increased with proper asymmetric fabric (hybrid) arrangements.


Shape memory performance of epoxy resin based composites

Recommendations for Future Works

  • Torsion, as loading mode, needs special attention.

  • Aramid fibers arepromisingcandidates.

  • Assessment of damage in shape memory cycle is essential for development of shape memory epoxy composites.

  • Because natural fibers can change the matrix’ Tg locally, multishape memory composites can be produced.

  • Tocombineshapememorywithselfhealing is a challengingstrategy - (multi)functionalpolymers.


Shape memory performance of epoxy resin based composites

Thank you for your attention.


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