We report in this article the results of nanosilica (SiO 2 )-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 (q), ultimate tensile strength, and hardness of the composites increased with SiO 2 weight fraction up to 10 wt % and decreased thereafter; this suggested that the beneficial properties occurred up to this weight fraction. The temperature and seawater aging had a negative influence on q; that is, q 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.

The tribological and electrical properties of epoxy composites filled with nano‐sized silica particles are studied and discussed in this article. To enhance the interfacial interaction between the fillers and the matrix, nanoparticles were pretreated with silane coupling agent. Dry sliding wear tests were carried out with configuration of composite sample on a rotating steel disc. Electrical measurements such as AC breakdown voltage, at 50 Hz, high voltage‐low current arc resistance and wet tracking resistance were carried out. The results reveal the influence of nanosized silica loading on wear resistance of the epoxy. It is observed that 10 wt% loading of silica is very effective in reducing the wear loss. With further increase of silica filler loading, the nanoparticles agglomerated and resulted in increase of the specific wear rate. The influence of silica particles on the specific wear rate is more pronounced under sliding wear situation. The influence of silica particle loading on epoxy is evident in the results of electrical parameters like dielectric strength, arc resistance and tracking resistance. These parameters showed improvement with filler loading up to 15 wt% and beyond this value of filler loading noticeable deterioration was observed. The effects of electrical stresses in the morphologies of the surfaces of epoxy nanocomposites are discussed. POLYM. COMPOS., 2011. © 2011 Society of Plastics Engineers

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This paper presents the development of epoxy-silica nanocomposites and characterized for dielectric properties. The effect of nanosilica loading (0-20 wt%), frequency, temperature and sea water aging on these properties was studied. Transmission electron microscopy (TEM) analysis of the samples showed an excellent dispersion. However, at higher silica loading TEM showed inter-contactity of the particles. The dielectric constant (e 0) increased with silica loading and reached an optimum at about 10 wt%. The e 0 of the nanocomposites showed linear decrease with frequency whereas AC conductivity (r ac) increases. The r ac and e 0 increased marginally with temperature and sea water aging.

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