Dipolar thermal relaxation of oriented, crystallized and γ-irradiated PET electrets

The motion of dipolar thermorelaxation for stretched, γ-irradiated and isothermal annealed semicrystalline poly(ethylene terephthalate) (PET) is investigated with the thermally stimulated current method. An α-peak of short-circuit thermally stimulated current is shifted to a higher temperature when the degrees of planar orientation and crystallinity are increased, and is shifted to a lower temperature when the γ-irradiation dose is increased. The activation energy of dipolar thermorelaxation for main-chain segmental motion in the amorphous region is decreased linearly and the time constant of dipolar thermal relaxation is enlarged exponentially with enhancing Δ(xy)z and Xc. The γ-irradiation does not have a pronounced effect on the activation energy and the time constant of dipolar thermal relaxation