Ultra-high Dielectric Constant of Poly(vinylidene fluoride) Composites Filled With Hydroxyl Modified Graphite Powders

We provide a one-step hydrothermal reaction to modify graphite powders (GPs) and prepare hydroxyl modified GPs/poly(vinylidene fluoride) (PVDF) composites which have excellent dielectric properties using high conductivity, low cost GPs as raw material. Fourier transform infrared spectroscopy (FT-IR) and X-ray photoelectron spectroscopy (XPS) showed that hydroxyl groups had been introduced to the surface of GPs. Scanning electron microscopy (SEM) showed that the hydroxyl modified GPs had better dispersion in the polymer matrix than the GPs. An ultra-high dielectric constant of more than 5.1 x 10(3) (dielectric loss is about 3.0) was obtained for the hydroxyl modified GPs/PVDF near the percolation threshold at 1 kHz. The hydroxyl modified GPs/PVDF composites exhibited better dielectric properties than most carbon/polymer composites. (C) 2014 Society of Plastics Engineers