Research on improving the insulation properties of epoxy filled with surface fluorinated polystyrene nanospheres

Abstract

Epoxy resin nanocomposites are widely used in the field of electronic 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 paper proposes a chemical copolymerization method, fluorinated polystyrene nanospheres were synthesized through an addition reaction as filler, and finally the epoxy nanocomposites were 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 1MHz frequency. In particular, the 2wt% fluorinated polystyrene/epoxy composite exhibits a decrease in dielectric constant and DC conductivity, while the AC and DC breakdown strengths increase by 12.6% and 6%, respectively.<br>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 introducing of fluorinated nanospheres significantly reduces the charge injection level. Calculations based on the depolarization process reveal that the introducing 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 the regulation of dielectric properties of epoxy composites and material synthesis for the application of electronic insulation packaging.