Thermally stimulated polarization and depolarization currents in polyethylene terephthalate succinate

When the temperature dependence of conduction current in biodegradable polyethylene terephthalate succinate (PETS) was measured, a hump appeared around 330 K under some conditions depending on whether the temperature was being ascended or descended and on whether the sample had been poled or short-circuited prior to the measurements. It seems that orientational polarization occurs by the glass transition and that its resultant current overlaps with the conduction current. Moreover, another current far larger than the polarization or depolarization current flows in PETS above 353 K, probably due to relaxation of polarized ionic species.