Abstract
The complex dielectric constants of ferroelectric copolymers VDF(81)/TeFE(19) with different crystallinities have been measured over the range of -120- +40°C and 10-2-10-4 Hz, using an improved dielectric relaxation spectrometer. The low-temperature processes of dielectric relaxation show that the frequency spectra of copolymers below room temperature consist of two parts: a low-frequency component which accords with a WLF equation and is ascribed to the micro-Brownian motions of frozen-in segments in the noncrystalline regions, and a high-frequency component which follows an Arrhenius rule and is designated as the local motions of small-scale segments in the crystalline and/or noncrystalline regions. The calculated results indicate that Tg of copolymers is -52°C and the activation energy of local relaxation is 37.7 kJ/mol.