The influences of different size SiO2 nanoparticles on dielectric properties and corona resistance of epoxy composites

In order to optimize the dispersion structure of the filler in polymer composites, 15 nm SiO 2 (HL‐150) and 6 nm SiO 2 (HL‐380) are added to epoxy (EP). The total content of silica filler is fixed at 15 wt%, and the mass ratio of HL‐380 to HL‐150 in silica filler is adjusted. SiO 2 /EP nanocomposites are prepared by the sand milling and heat curing process. Transmission electron microscopy results show that the mixed SiO 2 fillers are well dispersed in EP. With the increase of HL‐380 filler, the relative permittivity of the SiO 2 /EP nanocomposites with mixed SiO 2 nano‐fillers increases, compared with the nanocomposites added HL‐150 filler alone. The electrical aging threshold and dielectric strength increases, and the inhibiting effect on space charge accumulation is enhanced. When the mass ratio of HL‐380 to HL‐150 is 1/6.89, the corona resistance life are the longest, with the value of 13.23 hours, which is 1.47 times than that of the composites with HL‐150 filler alone.