Depolarization Relaxation Processes in Polyvinylidene Fluoride Films with Non-polar α-Crystalline Phase

The films with various orientation degrees were produced by polyvinylidene fluoride (PVDF) melt extrusion. The crystalline structure of the oriented films was studied using wide-angle X-ray scattering. The relaxation processes within the temperature range of 273–333 K were investigated using thermally stimulated depolarization (TSD) method. Within examined temperature range, two relaxation processes were observed, which are assumed to be associated with dipolar-segmental motion. The intensity of these relaxation processes declined as the degree of orientation increased. In order to study the influence of crystallinity degree on the observed relaxation processes, the extruded PVDF films were subjected to isometric annealing. It was observed that an increase in the crystallinity degree leads to the growth of thermally stimulated depolarization intensity in the temperature range of 300–310 K and its decrease in the temperature range of 280–290 K.