Electrical breakdown theories applied to polyethylene terephthalate films under the combined effects of pressure and temperature

On the basis of experimental results for the electrical breakdown field Fb in polyethylene terephthalate films, investigated previously under high hydrostatic pressure, P, from 50 to 500 bar at temperatures, T, of 35, 70, and 100 °C, the electromechanical and thermal breakdown models were used to explain variations in Fb. It was found by numerical calculations that the thermal breakdown model agreed better qualitatively and quantitatively with the negative temperature dependence and the positive pressure dependence of Fb than did the electromechanical model.