Influence of interface chemistry on dielectric properties of epoxy/alumina nanocomposites

This work was aimed to investigate the influence of alumina (Al₂O₃) nanoparticle surface modification on the micro structure and dielectric properties of epoxy nanocomposites. Al₂O₃ nanoparticles were first modified by two modifiers [i.e., γ-aminopropyl-tri-ethoxysilane (APS), hyperbranched aromatic polyamide (HBP)] and then their epoxy nanocomposites were fabricated. The nanocomposites with unmodified Al₂O₃ nanoparticles were also prepared for comparative research. Scanning electron microscope (SEM) and impedance analyzer were used to investigate the nanoparticle dispersion and frequency dependent dielectric properties of the nanocomposites, respectively. It was found that, compared with the epoxy nanocomposites filled with untreated Al₂O₃ nanoparticles, the nanocomposites with APS and HBP modified Al₂O₃ exhibit significantly improved nanoparticles dispersion in the epoxy matrix. It was also found that the dielectric constant of the nanocomposites was not dependent on the nanoparticle surface modification, whereas the dielectric loss of the nanocomposites can be influenced by the nanoparticle surface modification.