Abstract: In this paper,taking the commercial Teflon FEP films by Du Pont Co.,and the FEP (F_4,6) films by Shanghai Plastics Research Institute as examplis,the shift of mean charge depth during the TSD after corona cbarging at RT was studied by means of the heat pulse technique and thermally stimulated discharge.The transport rule of the detrapping charge in the bulk of the sample was discussed.Charge storge stabilities of the two types of positively corona charged polyfluoroe-thylenepropylene electrets at room temperature were compared.

Key words: polyfluorcethylenepropylene, electrets, mean charge depth, thermally stimulated discharge