Abstract
Polypropylene (PP) was used to study filler-polymer interactions when rice hull ash (silica ash) is used as a microfiller. Two sizes (47 and 20 μm) of silica ash particles were studied to obtain quantitative data on the composites' mechanical performance. The smaller particle size was obtained after communizing the original size. Nucleating effects were found, suggesting that there is a moderate polymer-filler interaction during melt-processing. A comparison of the effects of increasing filler loading and increasing surface treatment indicated that at higher filler loadings, the effect of surface treatment was not dominant. Reducing the filler particle size was found to improve tensile modulus and impact strength.
Removal of silica ash impurity by burning it off resulted in a significant increase in the above mentioned properties; however, similar results were not obtained after surface treatment of the unburnt ash. The results indicate that there is a possible trade-off between using the silica ash without burning, thus saving on the cost of burning off the impurities, and using the “burnt” ash and saving on the cost of surface modification.