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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: karger@pt.bme.hu. 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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  1. 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: karger@pt.bme.hu

  2. Outline • Introduction • Motivation • Possible applications • Properties of shape memory epoxy • Properties of shape memory epoxy composites • Future works

  3. Introduction Materials Non linear, Reversible Material’s property Functionalmaterials Structuralmaterials Ttrans Smart materials Smartmaterials Environmental condition (Temperature) Shapememorymaterials Shapememoryalloys Shapememorypolymers 20°C

  4. 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

  5. Schematic Architecture of SMPs J. Hu, Y. Zhu, H. Huang and J.Lu. Progr.Polym.Sci. 37 (2012), 1720

  6. Basic Differences Between SMA and SMP P. Ghosh et al.: Mater. Design 44 (2013), 164-171

  7. Motivation • Toincreaserecoverystresswithoutloosingthe • deformability • Attemptswithepoxyresin-basedcomposites

  8. 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)

  9. Property Tailoring with Epoxy Resins Storage modulus [MPa] Temperature [°C]

  10. Possible Applications of Shape Memory Epoxy Composites Solar array Deployable space structures Reflector J. Lenget al.: Progress in Material Science56 (2011), 1077-1126

  11. 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 RΣ 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

  12. 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.

  13. 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

  14. 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

  15. 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

  16. 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

  17. 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

  18. 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

  19. ELO/Flax Fiber Textile - Reinforced Biocomposites – Shape Memory Behavior Deformation 1 Fixation 2 Unload 3 Recovery 4

  20. 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

  21. 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.

  22. 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.

  23. Thank you for your attention.

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