Charging phenomena in polypropylene films

The influence of additives and impurities on conduction and polarization mechanisms in thin films of polypropylene was investigated. It was assumed that the charging current is made up of three components: a polarization component produced by dipole orientation, a conduction current, and a fast transient. The cause of each component was identified by means of a special nonlinear iterative algorithm based on the least-squares method. The results of this investigation show an influence of the additive content and of the temperature on the charging current that can be ascribed to the bulk composition of the materials. It is noted that it is very important to fit the experimental data in order to obtain the correct values of the steady-state conduction currents, which are more significant than the currents obtained at a fixed time