Development of Agro-Industrial Waste Reinforced Natural Rubber Composite: A Potential Formulation for Rubber Flooring Product

Agro-industrial waste has become a major environmental issue in most parts of the world. Rice husk is one of the major agricultural wastes especially in Asian countries. It is currently thrown away into landfills or rarely use as an alternative energy source, which in turn produce another waste, rice husk ash (RHA). Silica is the major component in well-burnt RHA. This work was aimed to evaluate the feasibility of utilizing silica extracted from RHA and another industrial waste, used tyre treads, with natural rubber to develop composite with enhanced mechanical properties especially for flooring products such as rugs, pavement blocks, door mats, etc. In this work extracted silica was characterized using Fourier-transform infrared spectroscopy, X-ray diffractometry (XRD), X-ray fluorescence spectroscopy (XRF) and scanning electron microscopy (SEM). The SEM images confirmed that the extracted silica is in the nanometer to sub-micrometer length scale in size. Further our results confirmed that extracted silica has comparable chemical composition and amorphous nature as commercially used silica in rubber compounding. Composites were first formulated using crumb rubber to identify the optimum crumb rubber loading. It is found that 25 phr of crumb rubber provides the optimal mechanical properties. Finally, extracted silica was incorporated to 25 phr crumb rubber loaded composite to further reinforcement. SEM images confirm that 10 phr of silica have enhanced matrix-filler interactions to produce continuous structure, which was not observed in crumb rubber loaded rubber composite.