Charging property and charge trap parameters in porous polypropylene film using thermally stimulated current

The heat resisting property of charge storage resins is required. It is well known that the charge storage of a polymer is influenced by the charge carrier traps. Charge trap parameters and charging property of porous and solid polypropylene (PP) films were studied using thermally stimulated current (TSC). We proposed already the Asymptotic Estimation Method (AEM) to evaluate trap parameters such as the energy depth of the trap E_t and the escape frequency factor ν from TSC spectrum caused by multiple carrier traps, separately. To describe the ν- E_t correlation, the trap sites caused by the porous structure were evaluated in the range of 1.0-1.1 eV. In addition, the ν values for those trap sites were found to be in the range 10¹¹-10¹² S^-1. A comparison of surface potential decay revealed that drawing treatment caused discharge property by heating and the porous structure in the PP film induced charge storage stability.