Properties of PS Grafted Alumina/Epoxy Nanocomposites

To enhance the interfacial interaction in alumina nanoparticles filled epoxy composites, an effective surface modification method was developed by grafting polystyrene onto the alpha-alumina nanoparticles. In this paper, the 3-methacryloxypropyltrimethoxy (KH570) agent was used to modify the surface of the alpha-alumina nanoparticles. Then, with the interface coupling and grafting technique, the polystyrene (PS) was proposed to graft on the nanoparticles by radical grafting polymerization in non-aqueous systems. Results of the FTIR (Fourier Transform Infrared) spectrum demonstrated that the desired polymer chains have been covalently bonded to the surface of the alpha-alumina nanoparticles. Five kinds of specimens with thickness of 200 mu m were prepared for investigation, which were neat epoxy, micro epoxy composite, and three kinds of epoxy nanocomposites with different contents of the same alpha-alumina nanoparticles. Properties including degradation temperature, glass transition temperature, dielectric breakdown strength, dielectric constant and dielectric loss have been measured. The results showed that the dielectric constant of PS-grafted-Al2O3/epoxy nanocomposites was increased when compared with neat epoxy. Among all the samples, 3 wt%-PS-grafted-Al2O3/epoxy nanocomposites showed the highest dielectric breakdown strength and it was improved about 5.67% and 35.37%, when compared with the neat epoxy and micro Al2O3/epoxy composites respectively.