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Effects of a static electric field upon dielectric properties of poly(vinylidene fluoride) and poly(vinyl fluoride)
Authors:Shigeyoshi Osaki  Shinsaku Uemura  Y ichi Ishida
Institution:Shigeyoshi Osaki,Shinsaku Uemura,Yōichi Ishida
Abstract:Dielectric measurements on poly(vinylidene fluoride) at higher temperatures result in anomalously large values of ε′ and ε″ at lower frequencies. When a static field is applied, a drastic decrease of ε′ and ε″ occurs. The effects of a static field can be summarized as follows: (1) the field effect upon ε′and ε″ is more significant at lower frequencies; (2) with increasing field strength, the rate of decrease of ε′and ε″ with time becomes greater and the ultimate values are smaller; (3) when the field is removed, ε′and ε″ recover but the ultimate recovery is incomplete; (4) the field effect depends strongly on temperature. Such behavior seems to be attributable to the displacement of ionic impurities and to their electrolysis. These results provided a method to remove the contribution of ionic impurities to ε′and ε″ and to measure the relaxation process due only to dipoles of a polymer. The application of this method revealed the dielectric high temperature absorption which had been masked by the ionic conduction in poly(vinyl fluoride).
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