Silica/white rice husk ash hybrid filler for rubber composites for the manufacture of low speed castor wheel rubber treads

The possibility of replacing a part of the 60 pph of commonly used silica filler imported from Wellink Chemical Co., India used in rubber composite for the manufacture of low speed castor wheel rubber tread formulations was studied. The curing characteristics and mechanical properties such as specific gravity, hardness, tensile strength, rebound resilience and abrasion volume loss of the composites prepared with varying amounts of White Rice Husk Ash (WRHA) ranging from 15 to 60 pph were determined. Results obtained were compared with those properties of the control composite containing 60 pph of commercial silica alone. The composites were then modified into a hybrid filler system by incorporating 6% (w/w) silane coupling agent based on the load of silica it contains. Commercial silica loading in the composite were varied from 10, 15, 20 and25pph, keeping WRHA loading at 45 pph at which loading, composites showed the closest properties to the properties of the controlled composite among candidate WRHA composites. Physical and mechanical properties of the vulcanizates were determined. The results showed that WRHA/Silica: 45/20 hybrid containing rubber vulcanizates exhibited the properties comparable to those of the vulcnizates of the control.

An approximate cost estimation analysis revealed that around 50% of the imported filler material cost saving could be achieved using this recipe instead of using only imported silica filler in the formulation to produce economically competitive tire treads.