Thermally stimulated currents in polymers driven by temperature gradients

Abstract

Nonisothermal currents were measured in poly(methyl methacrylate) and poly- (tetrafluoroethylene) samples, not polarized with external fields before the measurements. The currents were attributed to thermally stimulated reorientation of dipoles driven by temperature gradients across the samples. Calculations, based on a model put forward in the paper, are shown to satisfactorily reproduce basic features of the experimental curves. It is suggested that the room temperature peak in poly (tetrafluoroethylene) is due to a pyroelectric effect and is associated with a reorientation of impurity dipoles during the phase transition.