Epoxy resin nanocomposites are widely used in the field of electrical insulation packaging. It is of great significance to regulate the dielectric and insulation properties of composite materials by introducing nano-filler to meet special application requirements. This work proposes a chemical copolymerization method, fluorinated polystyrene nanospheres are synthesized through an addition reaction as filler, and finally the epoxy nanocomposites are prepared. The polystyrene nanospheres have a uniform size and good compatibility with the epoxy resin. The introducing of nanospheres reduces the dielectric constant of the epoxy resin composite material and increases the breakdown strength simultaneously. Although the dielectric loss increases, the composites’ imaginary part remains below 0.04 within 1 MHz frequency. In particular, the fluorinated polystyrene/epoxy composite with a mass fraction of 2% exhibits a decrease in dielectric constant and DC conductivity, while the AC breakdown strength and DC breakdown strength increase by 12.6% and 6%, respectively.

The results of the pulse electro-acoustic method indicate that the charge injection of the epoxy resin filled with non-fluorinated polystyrene nanospheres is evident, while the introduction of fluorinated nanospheres significantly reduces the charge injection level. Calculations based on the depolarization process reveal that the introduction of fillers leads to an increase in trap density and depth of energy levels in the composites. Notably, the epoxy resin filled with fluorinated fillers has the deepest trap levels, providing an explanation for the improved insulation breakdown performance. The research can provide guidance for regulating dielectric properties of epoxy composites and material synthesis for the application of electrical insulation packaging .