Shape memory effect contents

When the gel content was low (e.g., 40% or less), the samples did not recover fully upon heating. On the other hand, when the gel content was high, the complete final recovery rate was obtained indicating the requirement of a network structure to achieve the property of shape memory effect. 

Zhu Y, et al. Effect of cationic group content on shape memory effect in segmented polyurethane cationomer. J Appl Polym Sci 2007 103(1) 545—56. 

Effect of hard segment content on shape memory effect of the T -SMPUs. 

Abstract This chapter presents the thermaUy-indnced shape memory properties of supramolecular shape memory polyurethane (SMPU) containing pyriine moieties, and compares them with those of other types of SMPU. llie influence of the BINA content and the MDI-BDO content on the thermally-induced shape memory effects (SMEs) of these SMPUs are discussed, including shape fixity, shape recovery and shape recovery stress, as well as the temperature-dependent strain recovery process. A description and analysis of the mechanism of thermaUy-induced SMEs is also provided, covering the effect of temperature and pyridine content on the hydrogen bonds present in SMPUs. 

Abstract This chapter introduces the moisture-induced shape memory effect (SME) observed in supramolecular shape memory polymers, particularly shape memory polyurethane (SMPU), containing pyridine moieties. The moisture absorption of polyurethane networks containing pyridine moeties (PUPy) is discussed followed by an investigation into the effect of relative humidity (RH), temperature, BINA content and MDI-BDO content. The induence of moisture absorption on both the thermal properties and the dynamic mechanical properties of SMPUs is also described, along with the moisture-induced SME mechanism. 

Zheng et al. [150] described the shape memory properties of PDLLA/HAp composites. The results show that the content and degree of dispersion of HAp particles in PDLLA matrix strongly influence the shape memory effect. The shape recovery... 

The phenoxy/TPU blends showed a shape memory effect when the miscible PCL segment/phenoxy resin domains formed the reversible phase and the hard segment domains played the role of the frozen phase. The shape recovery could be designed at any temperature. Shape retention and recovery over 90% were generally obtained (Table 15). The hysteresis in shape recovery decreased as the hard segment content in the blend increased and the block length of TPU decreased. 

Y. Q. Liu, and H. M. Liem, "Effect of Cationic Group Content on Shape Memory Effect in Segmented Polyurethane Cationomer," Journal of Applied Polymer Science, vol. 103, pp. 545-556,2007. 

It is interesting to note that, while the CP content has a significant effect on the stress recovery, its effect on shape recovery is comparatively small. The reason is that shape recovery is basically a global or macroscopic behavior, while stress recovery is dependent more on the microstmeture and internal parameters. For instance, the recovery stress depends on the stiffness at the recovery temperature, while the recovery strain does not. Therefore, the shape recovery ratio and the stress recovery ratio usually do not have the same value and the stress recovery ratio is usually lower than the strain recovery ratio. In this sense, the stress recovery ratio is a more rigorous indicator of shape memory functionality. 

Further evaluation of the shape-memory behavior were exploring the effect of sampie thickness and HA content on the shape recovery ratio using a bending test (see Fig. 37). The composites were programmed by 180° folding and Rr was calculated using (5) [169] ... 

Zhu, Y, Hu, J., Yeung, L.-Y, Lu, J., Meng, Q., etal. (2007a), Effect of steaming on shape memory polyurethane fibers with various hard segment contents. Smart Materials and Structures, 16, 969-81. 

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