苯乙烯接枝改性纳米氧化铝环氧树脂复合材料的制备和性能研究

In order to improve the comprehensive electrical and thermal properties of traditional electrical epoxy composites, surface graft modification of nano-Al₂O₃ is applied to achieve better dispersion and interface strength in epoxy matrix, so as to improve its influence on the electrical and thermal properties of epoxy nano-composites. Bisphenol-A epoxy resin is taken as the matrix material, and the nano-Al₂O₃ particles coated with silane coupling agent and long-chain polystyrene (PS) are grafted and modified. The epoxy nano-composites with different mass fractions of surface-modified nano-Al₂O₃ are prepared by mechanical dispersion method. The effects of different contents of PS-grafted nano-Al₂O₃ on thermal stability, glass transition temperature, breakdown field strength and dielectric properties of the epoxy composites are studied. The results show that the grafted and modified nano-Al₂O₃ particles disperse evenly in the epoxy matrix. With the increase of doping amount, both the breakdown strength and electric constant of the grafted and modified nano-Al₂O₃ epoxy composite increase. Compared with neat epoxy, the grafted and modified nano-Al₂O₃/epoxy composite with 3% mass fraction shows the highest dielectric breakdown strength and the strength increases by about 5.67%. The dielectric constant of the nano-Al₂O₃/epoxy composite grafted with 5% styrene increases by 8.59%. It is concluded that grafting styrene to the surface of nano-Al₂O₃ can greatly improve the compatibility between the nano-particles and the polymer matrix, enhance the dispersibility and further improve the breakdown strength, which may provide a basis for the development and promotion of epoxy nanocomposites in the electrical field.