Electret properties in hybrid film consisting of porous PTFE and PP with negative corona charging

In this work the electret properties of hybrid film consisting of porous PTFE and PP, which come from Shanghai Dagong new materials Co. Ltd., are investigated by means of corona charging, open-circuit thermally stimulate discharge (TSD ) analysis and isothermal surface-potential decay measurement. The results indicate that there are space charge and polar charge for the hybrid film consisting of PP and porous PTFE charged by means of corona discharge method. When charging is through PP side, the space charge carriers are mainly trapped in PP layer and on the interface between PP and PTFE layers. The difference of TSD current spectra between the hybrid film consisting of PP with different physical appearance is very large. For PP materials the crystallites are the main source of space charge traps. The electric field generated by space charge can cause polarization of polymer and give birth to polar charge. The wider TSD current peaks are probably due to different structural traps originating from the mixture of two crystalline morphology PP.