The alternate polarization current method for conduction analysis in polymers

The alternate polarization current method, also known as alternate square wave method (asw), is an improved technique to characterize insulating materials. It consists in recording the transient current flowing during successive applications, on the sample, of alternate positive and negative steps of voltage of low magnitude, and averaging the data over a number of cycles. Whereas the conventional technique measures the current under a unique voltage step of generally rather high magnitude, hence in a more or less unsteady state leading to scattered results, and may involve injection process, the asw technique based on a dynamic equilibrium gives reproducible results. In this communication we present the results of measurements performed on two specimens of low density polyethylene using a new equipment of high sensitivity. Current vs. time characteristics using various poling stresses, step durations and temperatures are presented. Particular attention is paid on short time behaviour characterized by a t^-n decay function with n always larger than one. A way for physical interpretation is proposed. The interest of the method for material characterization is pointed out.