Shape memory, thermal conductivity, and mechanical property of polylactic acid and natural rubber composites reinforced by an inorganic thermal conductive network

Abstract: With the development and application of thermotropic shape memory polymer materials in the biomedical field, it is very crucial for these materials to improve their thermal conductivity efficiency and shape memory recovery rate by endowing them a high thermal conductivity. In our work, a PLA/NR/T-ZnOw/GR shape memory composite was prepared by melt blending with tetrapod zinc oxide whisker (T-ZnOw) and graphene (GR) as the double inorganic fillers and polylactic acid (PLA) and natural rubber (NR) as the polymer matrix. The synergism of T-ZnOw and GR constructs a three-dimensional (3D) thermal conductive network, making the thermal conductivity of PLA/NR/5wt%T-ZnOw/2.5wt%GR increase to 1.215 W∙(m∙K)−1. The addition of T-ZnOw reduces the agglomeration of GR in the PLA/NR matrix and the interfacial thermal resistance between the fillers and the matrix. It also improves the heat transfer rate, resulting in an excellent shape memory of PLA/NR/T-ZnOw/GR with a morphology recovery rate of ca. 96%, a fixed rate of 95% and high thermal stability. The presented biodegradable shape memory composite with the 3D thermal conductive network is promising in the fields of medical treatment and intelligent sensors.

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