The charge storage stability of porous polytetrafluoroethy lene film electret

ne excellent charge storage stability both for negatively and positively corona charged porous polytetrafluoroethylene (PTFE) was studied by the isothermal surface potential decay measurements after constant voltage corona charging at room and elevated temperatures, the corona charging at room temperature and then aged at different temperatures, as well as open-circuit Thermally Stimulated Discharge (TSD) experiments. The comparison of the charge storage stability was investigated among porous PTFE, non-porous PTFE(Teflon PTFE) and non-porous FEP (Teflon FEP) electrets. Their charge lifetimes (effective time constant) tau were estimated by means of isothermal depolarization program. The results show that porous PTFE has the best charge storage stability both for negatively and positively charged samples in organic electret materials, especially at high temperatures. The structure source of the excellent charge storage stability for the porous film electret was investigated by the scanning electron microscope