Surface potential behavior of fluorinated polyimide film under low temperature

The surface potential behaviors of fluorinated polyimide films under low temperature were studied to clarify the effects of fluorination time and low temperature. Polyimide specimens were fluorinated in a reaction kettle at 55 °C using a F2/N2 blend with volume fraction of 80% nitrogen and 0.05 MPa for respectively 15, 30, 45 and 60 min. The specimens without fluorination were also prepared for reference. Corona charging was performed with pulse voltage at a relative humidity of ~ 11% in atmospheric air. Then the specimens were cooled by liquid nitrogen in 10 s before or after corona charging. The surface potential was measured by the device of an electrostatic voltmeter. The experimental results indicate that the accumulation and decay behaviors of surface potential in the surface of polyimide films are affected by the charge polarity, specimen temperature and fluorination time.