No abstract

Different organic polyols were investigated as accelerators for different type of vulcanization system such as sulphur, metal oxide, peroxide with different rubbers such as natural rubber (NR), styrene butadiene rubber (SBR), butadiene rubber (BR), butyl rubber (IIR), nitrile rubber (NBR) and chloroprene rubber (CR). Among all the polyols studied, glycerol found to be the most efficient accelerator for sulphur vulcanization of unsaturated rubbers. Moreover, from rheometric study glycerol was found to be reversion free and scorch safe accelerator. A detailed study was performed with glycerol for sulphur vulcanization of silica filled, SBR + BR-based standard passenger car radial (PCR) tire tread compound and plausible mechanism of acceleration was proposed. Finally, from the PCR tyre tread compound 70% of conventional accelerators, namely N-cyclohexyl-2-benzothiazole sulfenamide (CBS) and di-phenyl guanidine (DPG) were replaced with 5 phr (parts per hundred gram of rubber) of glycerol and properties of the vulcanized compounds were measured. The results evidenced that glycerol could efficiently replace 70% conventional accelerators (CBS + DPG), with additional improvement of scorch time by 68%, tensile strength by 31.5%, elongation at break by 75.6% and tear strength by 9.4% of the PCR tyre tread compound. The increase in mechanical properties was due to the improvement in compatibility between silica and rubber in presence of glycerol. Moreover, glycerol is an environmentally benign (nitrogen free, halogen free), fossil free, low-cost material.

Biomaterials are obtained from renewable sources, low cost, abundant supply, environmentally friendly, fossil free and biodegradable. Therefore, the main objective of the present research is to use different biomaterials, such as carbohydrates (starches, celluloses), proteins and lignin in tire compounds without compromising tire properties and gaining possible advantages in terms of properties, cost, weight and environment. We have incorporated (10 phr, top up) different type of starches, such as maize, wheat, rice, cassava, and cellulosic materials, such as microcrystalline cellulose, sodium carboxymethyl cellulose, natural proteins, such as soya bean flour, and lignin in a silica filled tire tread compound and measured the properties to investigate if any of those materials can be used in tire. Among all these biomaterials, cassava, lignin and soya accelerate rate of vulcanization. Therefore, these materials can be used as bio-accelerator. Soya proteins imparts approximately 11% improvement in tensile strength and approximately 10% improvement in elongation at break. After the addition of biomaterials there is increase in marginal rolling resistance, increase in Payne effect and significant deterioration in wear property. Soya protein accelerate rate of vulcanization, improves mechanical properties, shows minimum deterioration in properties after ageing. Therefore, soya protein is the most suitable biomaterials among the materials studied for application in tire compound.