Abstract: Rice husk silica with a purity of 99.3% and a specific surface area of 212 m2/g was obtained by burning the HCl treated rice husk at 600℃. After being modified with γ-glycidyloxipropyltrimethoxysilane (KH-550), amorphous silica particles with size ranging from 30~50 nm were used as a filler in epoxy-based nanocomposites. The thermal degradation behavior and thermal stability of the epoxy resin/SiO2 nanocomposites were studied with thermo gravimetric analysis determining the initial decomposition temperature (Ti), temperature of maximum rate of weight loss (Tmax), and 50 % weight loss temperature (T50%). With increasing SiO2 content the thermal stability of epoxy resin was improved, which was further enhanced by the modification of SiO2. In addition，with the addition of silica, the tensile strength，elongation at breaking, and modulus were also increased.

Key words: Rice husk silica, epoxy resin, nanocomposite, thermal stability, tensile strength