Crystal Orientation and Temperature Effect on the Ferroelectric Behavior in a Poly(vinylidene fluoride-co-trifluoroethylene-co-chlorotrifluoroethylene)-graft-Polystyrene Graft Copolymer

摘要

Polymer dielectric films are important component for film capacitors because of their low dissipation factors, excellent high frequency responses, and high dielectric strengths. However, they suffer from low energy density. Recently, there is a need to develop high energy density polymer dielectric films. Ferroelectric polymers based on poly(vinylidene fluoride) (PVDF) and its copolymers appear to be a good choice for electric energy storage due to their relatively high permittivity and high dc breakdown strength. However, the hysteresis loss for PVDF and its copolymers is too high because of the delayed dipole switching when changing the electric field direction, namely spontaneous polarization. For example, at high electric fields, depending on the polymorphism, the hysteresis losses can be as high as 40-80%. Therefore, reducing the remanent polarization and/or the hysteresis loops is highly desired for developing ferroelectric polymers as high energy density and low loss dielectric films.