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 stor age time previous to depolarization on the free charge relaxation, rho , has been studied. It was noted that the temperature at which the rel axation maximum appears increases with the storage time, whereas the i ntensity of the maximum decreases. This behaviour depends on both the polarization temperature and the polarizing field. It was also observe d that there is a polarization temperature, the optimal polarization t emperature, for which the relaxation maximum temperature does not depe nd on the polarizing field.