Potential decay interpretation on insulating films: necessity of combining charge injection and slow volume polarization processes

We suggest that any interpretation of potential decay on insulating materials, especially at low fields, but not only, should carefully examine the hypothesis of slow polarization processes, often overlooked in the past. To verify this hypothesis, we achieved surface potential measurements on thin films of polypropylene and high density polyethylene, involving fields up to 10⁸ V.m^-1. We present here the first results of this study, concerning isothermal potential decay and potential profiles