Synergistic effect of hybrid carbon fillers on electric heating behavior of flexible polydimethylsiloxane-based composite films

Flexible polydimethylsiloxane (PDMS)-based composite films containing 1.0 wt% hybrid carbon fillers composed of multiwalled carbon nanotube (MWCNT) and graphene sheet were manufactured by an efficient solution-casting and curing technique. Microstructures and electrical properties of the composite films were quite dependent on the MWCNT/graphene ratios in 1.0 wt% hybrid carbon filler content. The composite film containing MWCNT/graphene of 9/1 weight ratio exhibited the lowest electrical resistivity of ∼73 Ω cm, which was even lower than the values of the composite films containing each single carbon filler, which resulted from the synergistic bridge effect of MWCNTs and graphene sheets that dispersed uniformly in the PDMS matrix. Accordingly, the electric heating behavior of the composite films was quite different, especially in the maximum temperatures attained at different applied voltages. The maximum temperatures of the composite films could be finely adjusted by tuning the hybrid carbon filler ratio as well as the associated electric power. In addition, the composite films, which were thermally stable up to ∼250 °C, showed excellent electric heating performance in temperature response, electric energy efficiency, and heating-cooling cyclic operation at given applied voltages.