Structures and Physical Properties of Graphene/PVDF Nanocomposite Films Prepared by Solution-mixing and Melt-compression

Abstract

We have manufactured poly(vinylidene fluoride) (PVDF)-based nanocomposite films with different graphene contents of 0.1 similar to 10.0 wt% by ultrasonicated solution-mixing and melt-compression. As a reinforcing nanofiller, graphene sheets are prepared by rapid thermal expansion of graphite oxide, which are from the oxidation of natural graphite flakes. Graphene sheets are characterized to be well exfoliated and dispersed in the nanocomposite films. X-ray diffraction data confirm that the alpha-phase crystals of PVDF are dominantly developed in the nanocomposite films during the melt-crystallization. DSC cooling thermograms show that the gaphene sheets serve as nucleating agents for the PVDF alpha-form crystals. Thermal stability of the nanocomposite films under oxygen gas atmosphere is noticeably improved, specifically for the nanocomposite with 1.0 wt% graphene. Electrical volume resistivity of the nanocomposite films is substantially decreased from similar to 10(14) to similar to 10(6) W cm, especially at a critical graphene content between 1.0 and 3.0 wt%. In addition, mechanical storage modulus is highly improved with increasing the graphene content in the nanocomposite films. The increment of the storage modulus for the nanocomposite film at 30 degrees C with increasing the graphene content is analyzed by adopting the theoretical model proposed by Halpin and Tsai.