Ferroelectric-to-paraelectric phase transition of vinylidene fluoride-trifluoroethylene copolymer

Abstract

The ferroelectricproperties of vinylidene fluoride‐trifluoroethylene copolymer were studied. The infrared absorption spectra and x‐ray diffraction patterns of the melt‐crystallized film suggested the similar crystalline form to the polar form I of polyvinylidene fluoride. It was found that the ferroelectric‐to‐paraelectric phase transition occurred at 70 °C and was the first order in the melt‐crystallized copolymerfilm by studying the dielectric constant,piezoelectric constant,D‐E hysteresis loop, and DSC measurement. The Curie constant was 2200 K. The phase transition was accompanied by the expansion of the crystal lattice.