Effect of liquid nitrogen on surface charge of polypropylene film under DC and pulse voltages

The surface charge behavior of polypropylene film processed with liquid nitrogen was discussed in this paper. And it was focused on the comprehensive influences on the accumulation and decay of surface charge by applying DC and pulse voltage in sequence. The DC voltage is constant in both amplitude and stressing time, while the pulse voltage varies in amplitude from 0 kV to 3.5 kV. By measuring the sample surface potential, a behavior pattern of the charges was revealed. The results showed that the charging by pulse voltage was influenced by both the Coulomb repulsion and the electric field intensity, while the decay of the charge was mainly affected by the voltage type, which was attributed to the difference in trapped depth of the charges on the sample surface.