Dielectric relaxation spectra in ferroelectric P(VDF-TrFE) copolymers

Dielectric spectroscopy (DS) and Thermally Stimulated Current (TSC) are employed to study the dynamics of Poly(VinyliDene Fluoride-TriFluoroEthylene) copolymers, Dielectric spectra reveal the existence of three relaxation processes : the beta relaxation or the glass transition relaxation, the secondary gamma relaxation present in the glassy phase and the Curie transition well characterized by a thermal hysteresis, TSC spectra are in good agreement with DS results and resolve the well known in semi-crystalline polymers alpha(c) relaxation process, as well as observed by Differential Scanning Calorimetry, The experimental DS data are analyzed using empirical Havriliak Negami function while TSC spectra are described in terms of compensation law and Hoffmann Williams Passaglia model of relaxation by means of fractional polarization technique, Curie - Weiss temperature T-o = 26 degrees C is determined by DS spectroscopy and the Curie transition is well described by a compensation law at T-c = 121 degrees C.