Effects of a static electric field upon dielectric properties of poly(vinylidene fluoride) and poly(vinyl fluoride)

Abstract

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).