Rapid potential decay on surface fluorinated epoxy resin samples

Epoxy resin samples were surface fluorinated using a F₂/N ₂ mixture with 12.5% F₂ by volume at 50% °C and 0.1 MPa for different times of 10, 30, and 60 min. Surface potential measurements at room temperature and different relative humidity levels of 20 to 60 on the surface fluorinated epoxy samples charged by corona discharge showed a low initial surface potential and a rapid potential decay, depending on the ambient humidity and fluorination time, in comparison with the charged unfluorinated epoxy sample. Surface conductivity measurements at the different relative humidity levels further indicated a higher surface conductivity of the fluorinated samples than the unfluorinated sample by over three orders of magnitude and an increase or decrease in surface conductivity with the ambient humidity or fluorination time, in accordance with the results of surface potential measurements. Attenuated total reflection infrared analyses and scanning electron microscope surface and cross section observations on the unfluorinated and surface fluorinated samples revealed substantial differences in physicochemical characteristics between the surface layers. The composition and structure characteristics of the surface layers are responsible for their intrinsic electrical properties and surface wettability, although surface morphology also influences the surface wettability.