Characterization of Nanosilica-Filled Epoxy Composites for Electrical and Insulation Applications

We report in this article the results of nanosilica (SiO2)-filled epoxy composites with different loadings and their electrical, thermal, mechanical, and free-volume properties characterized with different techniques. The morphological features were studied by transmission electron microscopy, and differential scanning calorimetry was used to investigate the glass-transition temperature (T-g) of the nanocomposites. The properties of the nanocomposites showed that the electrical resistivity (rho), ultimate tensile strength, and hardness of the composites increased with SiO2 weight fraction up to 10 wt % and decreased there-after; this suggested that the beneficial properties occurred up to this weight fraction. The temperature and seawater aging had a negative influence on rho; that is, rho decreased with increases in the temperature and aging. The free-volume changes (microstructural) in the composite systems correlated with seawater aging but did not correlate so well with the mechanical properties. (C) 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 121: 2752-2760, 2011