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DC breakdown and flashover characteristics of direct fluorinated epoxy/Al2O3 nanocomposites

The effect of direct fluorination on DC breakdown and flashover characteristics of epoxy/Al2O3 nanocomposites was investigated. Pure epoxy resin and epoxy/Al2O3 nanocomposites with 1, 3 and 5 wt% mass fractions were synthesized, and direct fluorination of the samples was carried out at 55 °C for 30 min using a F2/N2 mixture with 20 vol% F2 at 0.05 MPa. Fourier transform infrared spectroscopy and atomic force microscopy show that molecular chain scission occur during direct fluorination, which may significantly suppress surface charge accumulation while incorporating Al2O3 nanoparticles into epoxy may restrict surface potential decay of fluorinated epoxy resin. The trap characteristics obtained by isothermal surface potential decay show that 1 wt. % sample has deeper traps and higher trap density. DC breakdown and flashover of samples were measured to evaluate the influence of nano filling and direct fluorination on electrical performance of epoxy resin. The results show that epoxy resin with higher DC breakdown and flashover strength can be obtained by simultaneous application of nano filling and direct fluorination. Compared to un-fluorinated epoxy resin, the DC breakdown and flashover voltage of fluorinated epoxy/Al2O3 nanocomposites with mass fraction of 1 wt% improved 17 and 23%, respectively.