TSD currents in thermally aged and β-irradiated polyethylene terephthalate film

The influence of thermal aging and β-irradiation on TSD (thermal stimulated depolarization) current spectra of polyethylene terephthalate (PET) film was studied. Dynamics of the complex aging as well as changes in activation-energy temperature distributions were determined. A comparison of the activation-energy distributions for fresh samples and those β-irradiated with a dose of 15 Mrads and subsequently thermally aged shows that the character of the thermal dependence of the activation energies changes. There is a lack of defined energy levels, although the range of the activation energies remains similar. A different behavior, however, is observed for the samples that were irradiated with 5- and 10-Mrad doses. In those cases a new energetic level in the range of 1.2-1.9 eV is created