Electron-Irradiation Induced Phase Transition in Poly (Vinylidene Fluoride-Trifluoroethylene) Copolymer

Abstract

The electron-irradiation induced ferroelectric-to-relaxor phase transition in poly (vinylidene fluoride-trifluoroethylene) (P(VDF/TrFE)) copolymer was investigated. One polymer with a composition of 53 mol% VF 2 (PVDF53) and a Curie temperature of 67°C, and another with 76 mol% VF 2 (PVDF76) and a Curie temperature of 136°C, were used in the research. Changes in hysteresis loop, permittivity and electrostriction during the phase transition were measured. X-ray diffraction showed that PVDF53 had a second-order phase transition during the irradiation in which the structure was changing continuously, while PVDF76 had a first-order phase transition in which the structure changed discontinuously. Field-induced piezoelectric response was measured using a loudspeaker which provided a vibrational force, and d 31 = 135 pC/N at bias E 3 = 40 MV/m was obtained. The conditions for electron irradiation and composition of the copolymers were discussed.