Substantial reduction of carbon black and balancing the technical properties of styrene butadiene rubber compounds using nanoclay

Abstract

Carbon black is the prime component used in tyre manufacturing. Normally, 40–60 phr of carbon black is added in rubbers to enhance their physico-mechanical properties. Utilisation of high amounts of carbon black during tyre manufacturing will certainly lead to more fly loss, which may create several health hazards to humans involved in the mixing operation. This research work aims to partially replace carbon black with minimal nanoclay and balance the technical properties of styrene butadiene rubber (SBR) compounds. Organically modified polar nanoclay namely, Cloisters 30B was used in this study. Compatibility between SBR and Cloisite 30B was enhanced by introducing carboxylated styrene butadiene rubber (XSBR) as compatibiliser. Compatibilised SBR nanocomposites were developed by means of a two-step mixing process, where the required quantity of Cloisite 30B was dispersed in XSBR through a solution mixing technique. Further, the dried XSBR-Cloisite 30B films were incorporated in the bulk SBR matrix along with carbon black and curing agents through a mechanical mixing technique. For comparison, carbon black filled SBR compounds and dual filler (carbon black and cloisite 30B) filled uncompatibilised SBR compounds were prepared directly via a mechanical mixing method. Cure characteristics, morphology, wear behaviour and mechanical properties were analysed for the prepared rubber compounds. Compatibilised styrene butadiene rubber nanocomposite containing a dual filler exhibited an increase in maximum torque, tensile strength, modulus of elasticity, storage modulus and resistance to wear proving to be potential candidature for tyre applications. The obtained results confirmed that a minimal quantity of nanoclay (3.5 phr) and carbon black (20 phr) contributed to achieve desired technical properties of SBR compounds. In addition, it was observed that the addition of carbon black enhances the distribution of nanoclay bybreaking the nanoclay agglomerates in the SBR matrix, which indeed elevates the technical properties of the related compounds.