Influence of Sepiolite on Crystallinity of Soft Segments and Shape Memory Properties of Polyurethane Nanocomposites

The shape memory polyurethane/sepiolite nanocomposites were prepared with sepiolite dispersed uniformly in polyurethane based on poly(e-caprolactone). The influence of sepiolite on the structure of polyurethane was investigated by dynamic mechanical analysis, differential scanning calorimetry, X-ray diffraction, and polarized optical microscopy. The results show that sepiolite has little effect on the ordering of hard segments, but can act as a nucleating agent enhancing the crystallinity of soft segments. The maximum crystallinity of soft segments can be achieved when the content of sepiolite is 3 wt%. The results of shape memory test demonstrate that the addition of sepiolite improves the shape fixity ratio of polyurethane. The shape fixity ratio of polyurethane composite with 3 wt% of sepiolite reaches the maximum of 86.2%. The crystallinity of the soft segments can be adjusted by varying sepiolite content, which has a potential to realize controllability of shape memory properties. (C) 2016 Society of Plastics Engineers