MICROSCOPIC AND MACROSCOPIC EFFECTS OF ELECTRON-IRRADIATION ON FERROELECTRIC POLY(VINYLIDENE FLUORIDE-TRFE) COPOLYMERS

The effect of electron irradiation on ferroelectric poly(vinylidene-trifluoroethylene) copolymers has been studied from both microscopic and macroscopic points of view. Microscopically, it is found by x-ray photoemission spectroscopy analysis and ultraviolet absorption that the irradiation damaging is mainly through dehydrofluorination and leads to double-bond production and crosslinking. On the other hand, dielectric permittivity, internal friction, x-ray diffraction, and differential scanning calorimetry experiments show that both the ferroelectric transition temperature T(c) and the melting temperature T(m) are lowered under irradiation. These various experimental features are consistently analyzed taking into account three main mechanisms resulting from the electron irradiation: (i) reduction of the crystallite mean size, (ii) changes in the internal pressure, and (iii) reduction of the dipolar energy.