Polyurethane shape memory

Goo et al. investigated the actuation durability of a conducting shape memory polyurethane/MWNT (CSMPU) actuator and concluded that the number of cycles at breaking decreased, as the actuation temperature increased (108). The possible reason is that more material degradation of CSMPU can be induced due to rapid and large movement of polymer chains as the actuation temperature increases. For a CSMPU actuator, the authors confirmed that an actuation temperature that is higher than the transition temperature produces a rapid response but low durability. 

It is therefore no surprise that shape memory polyurethanes (SMPUs) have emerged as front-runners in this very rapidly growing field of interest and have subsequently been commercialised. The hard and soft features of SMPUs are shown in Figure 1.4. 

As compared to metallic compounds used as shape memory materials, shape memory polymers have low density, high shape recoverability, easy processability, and low cost. Since the discovery by Mitsubishi in 1988, polyurethane SMPs have attracted a great deal of attention due to their unique properties, such as a wide range of shape recovery temperatures (— 30°C to 70°C) and excellent biocompatibility, besides the usual advantages of plastics. A series of shape memory polyurethanes (SPMUs), prepared from polycaprolactone diols (PCL), 1,4-butanediol (BDO) (chain extender), and 4,4 -diphenylmethane diisocyanate (MDI) or toluene diisocyanate (TDI) have recently been introduced [200—202]. 

Shape memory polyurethane fiber Comfort elasticity Body temperature active... 

Presently, the study of shape memory polyurethane (SMPU) has been widely conducted. For common elastic fibers, the elasticity should be defined as the instant recoverability of the length on release of the deforming stress. The recovery in shape memory fibers is the ability of deformed fibers to recover under external stimulus such as heat or chemicals. In this case, the external stimulus is a must. Figure 3.1 shows the net-points and switches which response to the stimulus (Hu et al., 2012). The elongation of shape memory polymer fiber are a little less than spandex, but mechanical... 

Figure 3.3 Development of shape memory polyurethane fibers.

J. Rodriguez, F. Qubb, T. Wilson, M. Miller, T. Fossum, J. Hartman, E. Tuzun, P. Singhal, D. Maitland, In vivo response to an implanted shape memory polyurethane foam in a porcine aneurysm model. J. Biomed. Mater. Res. A (2013) doi 10.1002/jbm.a,34782. 

Barikani, M., Zia, K.M., Bhatti, I.A., Zuber, M., Bhatti, H.N. Molecular engineering and properties of chitin based shape memory polyurethane elastomers. Catbohydr. Polym. 74(3), 621-626 (2008)... 

Mondal, S., and Hu, J. L. 2007. Water vapor permeability of cotton fabrics coated with shape memory polyurethane. Carbohydrate Polymers 67 282-287. 

One of the important developments in, and applications of, textiles is the manufacture of intelligent waterproof breathable fabrics based on shape memory polymers using shape memory polyurethanes. The fabric restricts the loss of body warmth by stopping... 

Ding XM, Hu HL, Tao XM. Effect of crystal melting on water vapor permeability of shape-memory polyurethane film. Text Res J 2004 74(l) 39-43. 

Healing of Thermosetting Polymer by Embedded Unidirectional (1-D) Shape Memory Polyurethane Fiber (SMPF)... 

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