Flexural Strength and Dynamic Mechanical Behavior of Rice Husk Ash Silica Filled Acrylic Resin Denture Base Material

Silica extracted from rice husk ash (RHA-Si) by pretreatment with hydrochloric acid followed by calcination at 700°C, was prepared. It was investigated with regard to its chemical composition and structure using X-Ray Fluorescence spectroscopy (XRF) and X-Ray Diffractometry (XRD). RHA-Si (0, 0.25, 0.5 and 1% w/w) was incorporated into poly(methyl methacrylate) (PMMA) or acrylic resin powder. Microhardness, flexural strength and dynamic mechanical properties of RHA-Si filled PMMA were then determined. The chemical composition analysis showed that RHA-Si contains a large amount of silica with an amorphous structure. The microhardness of acrylic resin filled with RHA-Si does not change significantly with increasing RHA-Si loading. Flexural strength of filled acrylic resin increases with increasing RHA-Si loadings up to 0.25% w/w. It then decreases with increasing RHA-Si loadings. Dynamic mechanical behavior illustrates that polymer-filler interactions play an important role in reinforcement.