STORAGE TIME EFFECT ON FREE CHARGE RELAXATION OF AMORPHOUS POLY(ETHYLENE-TEREPHTHALATE)

Using thermally stimulated depolarization currents of PET-a electrets formed by the windowing polarization technique, the effect of the storage time previous to depolarization on the free charge relaxation, rho, has been studied. It was noted that the temperature at which the relaxation maximum appears increases with the storage time, whereas the intensity of the maximum decreases. This behaviour depends on both the polarization temperature and the polarizing field. It was also observed that there is a polarization temperature, the optimal polarization temperature, for which the relaxation maximum temperature does not depend on the polarizing field.