Thermally stimulated currents from corona-charged polypropylene films: A thermal effect of vacuum deposition of metallic electrodes

Abstract

It is demonstrated that the thermally stimulated currents (TSC) from positively or negatively corona-charged polypropylene strongly depend on the order of the following two processes: a process of vacuum deposition of Al electrodes on the sample polymer and a process of heat-treatment of the polymer. Observed results are explained by a thermal effect which is introduced during the vacuum deposition of metallic electrodes. This thermal effect of the vacuum deposition of metallic electrodes is the largest for Al and the smallest for Bi among Al, Au, Ag, and Bi. Observed TSC spectra have three peaks at about 68, 142, and above 147 °C for positively charged samples and four peaks at about 48, 90, 142, and above 147 °C for negatively charged samples, respectively. Origins of these TSC peaks are discussed in some detail.