Properties of PAAM Grafted alumina/epoxy nanocomposites

The electric properties of nanocomposites are determined by the interface between nano particles and epoxy resin, so the interface modification is very important. In this paper, silane coupling agent which has a carbon-carbon double bond and an oxymethylphenyl was used to modify the surface of α-Al₂O₃. In the modification, carbon-carbon double bonds were introduced to the surface of nano particles. The carbon-carbon double bonds will serve as active groups in the grafting process. The polyacrylamide (PAAM) was grafted on the surface of α-Al₂O₃. And the amino groups were introduced to the surface of α-Al₂O₃. Then the interface between the nano particle and the epoxy resin can be reinforced by the reaction between the amino group and epoxy ring. The FTIR (Fourier Transform Infrared) spectrum of grafted alumina was tested to confirm the modification and grafting process. Then, five kinds of materials were prepared, i.e. neat epoxy, micro composites, and three kinds of nanocomposites with different contents of PAAM grafted alumina particles. The specimens with thickness of 200 μm were prepared for investigation. The SEM micrographs were investigated to observe the dispersion of nano particles in epoxy resin. And the properties including the thermal behavior, dielectric strength, and dielectric spectrum were measured and analyzed. It is concluded that the epoxy nanocomposites loaded with PAAM grafted alumina particles show homogeneous dispersion, increasing thermal degradation initiation temperature and higher dielectric breakdown strength.