Rice Hull Nano Silica as Fire Retardant in Epoxy Composites


Previous Studies in our laboratories have shown that the incorporation of silica hull derived nano size silica into epoxy composite material can enhance the mechanical properties of such composites. The present study was aimed at monitoring the effects of rice hull silica on fire retardant properties of composites fabricated with a commercially available epoxy resin and epoxidized allyl soyate (EAS). The silica used in the study was obtained from rice hulls after acid digestion and combustion at 700°C. The high purity silica was ball milled to obtain nano particles which were mixed with epoxy resins at varied concentrations. Composite materials with and without rice hull silica were subjected to standard mechanical and thermal tests. Fire retardant properties of the composites were assessed through horizontal burn and cone calorimeter tests. The horizontal burn showed that silica containing composites exhibited markedly slower burn rate and suffered minimal mass loss compared to materials which did not contain silica. The controlled atmosphere cone calorimeter tests were conducted to assess the effect of oxygen concentration and silica reinforcement on burning behavior of epoxy composites. Results obtained were in agreement with the results of horizontal burn tests. Similar results were obtained in thermo gravimetric analysis (TGA), which showed that mass loss for silica containing composites was significantly lower than the mass loss for silica free composites.



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