Shape memory polymers effect

Figure 1.2 Schematics of thermally induced shape memory polymer effect.

Strain hardening effect, 20 224 Straining efficiency, 77 340 Strain rate, 73 473 Strain recovery rate (Rr), in testing shape-memory polymers, 22 361 Strain sensors, 77 150, 151-152 Strain tensor, for noncentrosymmetry pont group crystals, 77 93-94 Strain versus time curve factors affecting, 73 473 material and microstructure effect on, 73 473-474... 

Figure 1.7 (a) Shape memory polymer in position, (b) Operational effect of the strip around an assumed leg. (c) Pressure gradient requirement from the ankle to below the knee. 

FIGURE 19.4 Molecular mechanism and macroscopic effect of a shape-memory polymer, (a) Schematic representation of the thermally induced shape-memory effect of a polymer network with (b) Shape recovery of a stent with T = 52° in water at 37°C. The stent gradually changed from its... 

Molecular mechanism of thermally triggered shape memory effect of polymers. T, 5 = thermal transition temperature related to the switching phase. (Adapted from Lendlein, A., and Kelch, S. 2002. Shape-memory polymers. Angewandte Chemie, International Edition 41 2034-2057. Copyright Wiley-VCH Verlag GmbH Co. KGaA. Reproduced with permission.)... 

Figure 3.1 Various molecular structures of shape memory polymers (SMPs). A stable network and a reversible switching transition are the prerequisites for the polymers to show the shape memory effect (SME). The stable network can be molecule entanglement, chemical cross-hnking, crystaUization, and IPN the reversible switching transition can be the crystalUzation/melting transition, vitrification/glass transition, anisotropic/isotropic transition, reversible chemical cross-linking, and association/disassociation of supramolecular structures. Source [22] Reproduced with permission from Elsevier...

In order to perform programming and recovery effectively, the glass transition temperature (T ) must be determined first as the shape memory effect of thermosetting shape memory polymers revolves around a temperature range centered at the Tg. Below this range the material is rigid or glassy and above it is in a rubbery-elastic state. Recovery must be conducted within or above... 

Sun, L. and Huang, W.M. (2010) Mechanisms of the multi-shape memory effect and temperature memory effect in shape memory polymers. Soft Matter, 6, 4403 1406. 

Xu, T., Li, G., and Pang, S.S. (2011) Effects of ultraviolet radiation on morphology and thermo-mechanical properties of shape memory polymer based syntactic foam. Composites Part A Applied Science and Manufacturing, 42, 1525-1533. 

Li, G., Ajisafe, O., and Meng, H. (2013) Effect of strain hardening of shape memory polymer fibers on healing efficiency of thermosetting polymer composites. Polymer, 54, 920-928. 

Shape memory polymers (SMPs), due to their unique shape memory effect, may find applications in civil engineering structures, in addition to the applications in fiber reinforced lightweight polymer eomposites, which are focus of this book. As an example, we would suggest some potential applieations in pavement stractures, which are the backbone for transportation in many eountries in the world. 

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