Isothermal charge decay of Teflon-FEP electrets under a corona discharge

Corona-polarized Teflon-FEP electrets, with a negative bias voltage at the sample holder of a corona triode, show a decrease of the surface potential. Heat pulse measurements taken while treating the sample show that the charge centroid always remains on the sample surface. This indicates that there is no charge injection into the bulk, as has been suggested for other polymers. No loss of charge by surface conductivity is observed. The results are tentatively explained by charge compensation with positive ions arriving at the sample surface