High-field transient conduction in PET in the microsecond-millisecond time range

Abstract

The transient current in polyethylene-terephthalate resulting from the application of a voltage step is studied in the temperature range 90-160 degrees C at field strengths ranging up to 3.2 MV cm^-1. The current is recorded in the time scale extending from approximately 50 mu s to 1 ms as measured from the edge of the voltage step. A prominent feature of the current, particularly below 140 degrees C, is its monotonic decay with time. On Fourier transformation of this data into the frequency domain a strong correspondence is found with low-field AC dielectric loss measurements. A specifically high-field conduction mechanism dominates the conduction with increasing temperature above 140 degrees C, and the current is then found to be only weakly dependent on the time.