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(ε ‐ 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. POLYM. COMPOS., 39:1674–1681, 2018. © 2016 Society of Plastics Engineers