Synergistic effect of Hisil/carbon black hybrid filler on natural rubber/styrene butadiene rubber nano-composite using gamma radiation and sorbic acid as eco-friendly curing agents

Abstract Gamma radiation aging degradation of natural rubber and its blends: Role of sulphur-based curing agent. Gamma irradiation is a suitable method for the enhancement of elastomeric breakdown products through radiation crosslinking, which can improve the mechanical properties and service performance. In the present work, hybrid-filled natural rubber (NR)/styrene butadiene rubber (SBR) (50/50) composites containing a constant carbon black loading of 50 parts per hundred (phr) and different amounts of precipitated silica (Hisil, 0–20 phr) were prepared and exposed to gamma rays with absorbed doses of 0, 100, 150 and 200 kGy. The influence of silica loading and gamma irradiation on compression set and elastic recovery of the composites was also assessed in a consecutive manner. The results indicated that with the increase of the Hisil concentration, the elastic recovery was improved and compression set was reduced stepwise due to the reinforcing mechanism of silica as well as stronger filler–rubber interaction, which induced the formation of a more stable and rigid network structure. The performance of the composites was further improved by gamma irradiation as the increased crosslink density led to reduced permanent deformation and enhanced elastic recovery. The unique synergy between higher Hisil loading and gamma irradiation resulted in the best compromise of filler reinforcement and radiation-induced crosslinking among components, and gave the undoubted best mechanical stability and long-term durability. These results indicate that tuning both silica concentration and gamma irradiation dose is a promising, but more generic, approach to tailor the structure and properties of NR/SBR composites for advanced sealing and engineering uses.