Effects of reduced graphene on crystallization behavior, thermal conductivity and tribological properties of poly(vinylidene fluoride)

Abstract

The reduced graphene/poly(vinylidene fluoride) nanocomposite films were prepared by the solution casting-thermal reduction process using graphene oxide and poly(vinylidene fluoride) resin. The results show that with the presence of reduced graphene nano sheets in the nanocomposite, the structure of poly(vinylidene fluoride) tends to transform from α- to β-phase and the β-phase fraction and its crystallinity are largely affected by the reduced graphene content. The thermal conductivity of poly(vinylidene fluoride) can be effectively improved by the reduced graphene nano sheets introduction and when the reduced graphene content increased to about 10.0 wt%, it is about two times higher than the pure poly(vinylidene fluoride), due to the excellent thermal conductivity of reduced graphene and formation of thermal conductive networks. With comparison of the pure poly(vinylidene fluoride), the reduced graphene/poly(vinylidene fluoride) nanocomposite films show a better tribological property at a low reduced graphene content (below 4.0 wt%), mainly owing to the lubricant and heat spreading effects of reduced graphene nano sheets. The friction coefficient and wear rate for 0.75 wt% reduced graphene/poly(vinylidene fluoride) nanocomposite film compared to the pure poly(vinylidene fluoride) are improved by 41.2% and 49.4%, respectively.