Effect of long-term fluorination on surface electrical performance of ethylene propylene rubber

To investigate the effect of fluorination on surface electrical performance of ethylene propylene rubber (EPR), four pieces of EPR specimens are prepared and fluorinated for different duration ranging from 120 min to 480 min. The surface morphology and element compositions of experimental specimens are tested. The surface potential decay and complex permittivity are measured. The tracking discharge property and the erosion properties after tracking test are investigated. The surface charge transport and electrical property tailoring mechanism are discussed. The results show that when the fluorination duration is from 120 min to 360 min, the surface morphology gradually becomes flat and compact with time, and the surface resistance to electrical tracking is improved. While an excessive fluorination with the duration of 480 min leads to a significant increase in surface conductivity and a weakening in the resistance to electrical tracking, which is mainly due to a change in surface morphology. The recommended fluorination duration for an optimised surface property is between 240 and 360 min for EPR specimen.