Influence of water absorption on dielectric properties of epoxy SiO2 and BN nanocomposites

It is well known that epoxy resins would absorb water when left in ambient conditions. A number of hydrophilic nano-particles also absorb water, like nano-SiO2, because of their surface hydroxyl groups resulting from the manufacture process. The water uptake will affect dielectric properties of the nanocomposites. However there was conflict report on the amount of water uptake by the unfilled and nano-filled epoxy resin systems. In the present paper, the epoxy resin was filled with surface treated, as well as, untreated nano-SiO₂ and nano-BN. The relative humidity is controlled by the desiccator (dry samples), de-ionized(100% RH) water and climate chamber. The dielectric properties will relate to the hydration of samples. Measurements of dielectric spectroscopy cover the range of frequency from 10-2-105 Hz. Dielectric spectroscopy also showed different capacitance and permittivity at low frequencies, as well as tand, which depend on the hydration and temperature. It was observed from the results that permittivity, capacitance and tanδ of pure epoxy were strongly affected by the water absorptions. All these results are used to analyse how different variables, like surface treatment, filler type and filler loading concentration, can influence the water absorption. It will allow us to extract the influence of water absorption on dielectric properties of epoxy nanocomposites.