Electrical Capacitance of Polyethylene under Application of High DC Electric Field

Abstract

An increase in the electrical capacitance of polyethylene is detected when a high dc electric field is applied with a variable-frequency oscillator. The increment of capacitance increases in proportion to the square of the applied field and changes reversibly below about 30 MV/m for gold electrodes. This change in capacitance is due to the effect of electromechanical compressive stress. Above 30 MV/m, the capacitance undergoes an irreversible change and the increase in capacitance is discussed in terms of the polarization of trapped electronic space charges injected from the electrode. In the region above about 90 MV/m, where the conduction current obeys Child's law, the increment of capacitance with field again becomes proportional to the square of the applied field and may be explained by free carrier polarization.