Regulation of surface resistivity and enhancement of surface flashover voltage in epoxy resin through the directional migration of fluorinated segment

This study presents the preparation of epoxy resin composites with fluorinated segment migration (FBEP) through the fluorination grafting modification of the epoxy resin matrix and optimization of the curing process to achieve effective regulation of surface resistivity. A stepwise curing procedure process was used to enhance the enrichment of fluorocarbon segments on the material surface, forming a fluorine-rich layer that regulates the distribution of traps. Experimental results show that as the pre-curing time is extended from 2 h to 10 h, the surface fluorine content increases from 3.8 wt% to 4.5 wt%, which leads to a decrease in surface resistivity from 4.243×10 15 to 1.346×10 15 Ω. Simultaneous measurements revealed a significant increase in the surface charge migration efficiency, with the surface potential decay amount after 22000 s increasing from 13.69% for FBEP-2 to 34.40% for FBEP-10. Moreover, the shallow charge trapping sites within the fluorine-rich layer effectively suppressed charge accumulation, causing the surface flashover voltage to rise from 21.13 to 27.70 kV, a 31.03% increase. The fluorinated segment directed migration strategy proposed in this study provides a novel solution for the coordinated enhancement of both surface resistivity and surface flashover voltage in epoxy resins.