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 consideration that the lowest threshold level for electrical aging is related to build up of steady space charge, high-field current measurements performed at different voltage and temperature values, seeking space charge limited current conditions, can provide estimations of electric field at threshold. This approach is applied to PET films under dc voltage. The values of electrical threshold thus obtained are compared with those derived from conventional accelerated life testing, showing that there is good correspondence of values at the lowest temperature of the test range, while deviation between estimates increases with temperature.