Study on relaxation process of fluorinated graphite/poly(vinylidene fluoride-hexafluoropropylene) composites by dielectric relaxation spectroscopy

Abstract

The Fluorinated Graphite (FG)/poly(vinylidene fluoride-hexafluoropropylene) [P(VDF-HFP)] composites with different FG contents were prepared using the solution casting method, and the dielectric relaxation behaviors of the composites were systematically investigated by dielectric relaxation spectroscopy (DRS) with the frequency range of 20 Hz–5M Hz at the temperature range of 25 °C–200 °C. The dielectric constant of these FG/P(VDF-HFP) composites markedly increased and the dielectric loss decreased with the FG content. The electric modulus and Cole-Cole plots were employed to analyze the experimental complex dielectric constant, indicating that all the samples exhibited non-Debye relaxation process, especially in FG/P(VDF-HFP) composites. The temperature dependencies of relaxation time obtained from electric modulus analysis and conductivity relaxation obeyed the Arrhenius equation. Compared with pure P(VDF-HFP), the DC conductivity relaxation and the activation energies (Eτ and Eσ) of FG/P(VDF-HFP) composites gradually decreased with increasing FG composition because the mobility of charge carriers can be confined and merely fast hopped between the insulating fluorine atom layer.