Stabilization of positive charge in fluorinated ethylene propylene copolymer

Stabilization of positive charge in fluorinated ethylene propylene copolymer (Teflon FEP) is demonstrated using corona charging through a controlling grid at elevated temperatures. The extrapolated lifetime of the equivalent surface potential is 800 yr for samples charged at 150 °C and deteriorates for lower charging temperatures. Obtained results for the trap structure confirm published data on the same material. Activation energies, determined by the initial rise of thermally stimulated current measuremnts, are 0.63, 1.16, 1.43, and 1.5 eV for samples charged at 30, 60, 90, and 150 °C, respectively. A uniform charge distribution throughout the bulk of the material is found in samples charged above 100 °C. The total density of occupied traps decreases from 2.2×10¹⁴ cm⁻³ to 1.0×10¹⁴ cm⁻³ when charging at temperatures ranging from 100 to 180 °C.