SEARCHING FOR SHORT-TERM TECHNIQUES FOR THE INFERENCE OF ELECTRICAL THRESHOLD OF PET - DC CONDUCTIVITY MEASUREMENTS

A possible way for the detection of electrical threshold in dielectric polymers is illustrated in this paper, On the basis of the considerat ion that the lowest threshold level for electrical aging is related to build up of steady space charge, high-field current measurements perf ormed at different voltage and temperature values, seeking for space c harge limited current conditions, can provide estimations of electric field at threshold. This approach is applied to PET films under dc vol tage. The values of electrical threshold thus obtained are compared wi th those derived from conventional accelerated life testing, showing t hat there is good correspondence of values at the lowest temperature o f the test range, while deviation between estimates increases with tem perature.