The effect of coupling agent and chemical treatment on rice husk ash-filled natural rubber composites

Rice husk ash was incorporated into natural rubber (NR) using a laboratory size two-roll mill. Curing using a conventional vulcanization system (CV) w as chosen, and cure studies were carried out on a Monsanto rheometer. Physi cal testing of the NR vulcanizates involved the determination of tensile, t ear, and abrasion resistances, and hardness. Fourier transform infrared spe ctroscopy (FTIR) analysis was done to verify the presence of the characteri stic functional groups of precipitated silica in MHA (milled husk ash) and THA (treated husk ash). The effect of the coupling agent, bis(3-triethoxysi lylpropyl)-tetrasulfane (Si-69), on the curing and physical properties of t he vulcanizates was investigated. A chemical treatment on a rice husk ash w as done, and the effects of this procedure are also reported. For compariso n, two commercial fillers, precipitated silica (Zeosil-175) and carbon blac k (N774), were also used. Although the presence of the silane coupling agen t had not brought the expected increase in properties, treated husk ash sho wed exceptional performance in terms of tensile strength and abrasion resis tance of the filed vulcanizates. (C) 2000 John Wiley & Sons, Inc.