A novel method to incorporate functional filler into TPSiV for balanced physical properties

Abstract

Various literatures have reported that incorporating functional fillers into thermoplastic vulcanizates (TPVs) is an ideal method to prepare functional TPVs with balanced properties. Nevertheless, it is quite difficult to achieve that for thermoplastic silicone vulcanizate (TPSiV) due to their rather high silicon rubber (SiR) content as well as delicate balance between processing ability and various physical properties. Herein, a novel method involves using CNT/TPU phase as polymer matrix to disperse TPSiV particles through solution processing is proposed. Compared with randomly dispersed CNTs and traditional segregated CNTs network with TPSiV particles, composites fabricated by such method illustrate much better balance between various properties, including: low percolation threshold (Pc), comprehensive mechanical performance, better electromagnetic interference (EMI) shielding ability, etc. CNT/TPU anchored TPSiV double-percolated composite illustrates comparable Pc (0.42 wt%) to traditional segregated TPSiV/CNT composite (0.38 wt%), while the TPSiV composite with randomly dispersed CNT shows apparently high Pc (1.37 wt%). More importantly, both tensile strength and elongation at break are improved for these compoistes with double-percolation structure. It is even better than neat TPSiV composites at the same CNT loading. The prepared two types of segregated composites demonstrate similar electrical conductivity at high filler loading (≥1 wt%), enabling them with similar EMI performance, but the one with CNT/TPU as adhesive phase is much more stable after 100 times bending, illustrating negligible attenuation. This study provides a novel approach for incorporating functional fillers into TPSiV matrix for balanced properties.