DIELECTRIC RELAXATIONS IN FERROELECTRIC COPOLYMER VINYLIDENE FLUORIDE(65)/TRIFLUOROETHYLENE(35)
ZHANG XING-YUAN (张兴元)a, TAKEO FURUKAWAb
a Department of Materials Science and Engineering, University of Science and Technology of China, Hefei 230026, China; b Department of Chemistry, Science University of Tokyo, 162 Janpan
Abstract The molecular motion characteristics of ferroelectric copolymer vinylidene fluo-ride(65)/trifluoroethylene(35) have been investigated by means of dielectric relaxation. The frequency spectra of the copolymer consisting of low-frequency and high-frequency compo-nents are observed below room temperature. With the rise of crystallinity, the Curie point decreases while the dielectric constant increases in the region of ferroelectric-to-paraelectric phase transition. Based on the fitting results using one or two Cole-Cole functions, and cal-culating with the WLF equation and an Arrhenius formula, the glass transition temperature (= -28℃) and the activation energy of local relaxation (= 54.4 kJ·mol-1) of the copolymer are obtained. It is found that the distribution of relaxation time in the molten and the ferroelectric phases is located at a same line, which complies with the Arrhenius rule. This indicates that the elementary motions are of the same type for molecular motions provided by the high-temperature process and the low-temperature local mode process.
Received: 14 July 1994
Accepted manuscript online:
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