LOW-TEMPERATURE LOW-FREQUENCY DIELECTRIC RELAXATIONS IN VDF(81)/TeFE(19) COPOLYMERS
ZHANG XING-YUAN(张兴元)a, TAKEO FURUKAWAb
a Department of Chemistry, Science University of Tokyo, 162 Japan; b Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China
Abstract The complex dielectric constants of ferroelectric copolymers VDF(81)/TeFE(19) with dif-ferent crystallinities have been measured over the range of-120- +40℃ and 10-2-10-4 Hz, using an improved dielectric relaxation spectrometer. The low-temperature processes of di-electric 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℃ and the activation energy of local relaxation is 37.7 kJ/mol.
Received: 07 April 1993
Accepted manuscript online:
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