Enhancing gamma-irradiated NBR/PVC blends with sulfur nanoparticles as a crosslinking promoter

The development of polymer nanocomposites is crucial for meeting increasing industrial demands. This research investigated the use of synthesized sulfur nano-particles (S-NPs) as a vulcanizing agent in acrylonitrile butadiene rubber (NBR) and polyvinyl chloride (PVC) blends, which were subsequently exposed to 50 kGy of gamma irradiation. Structural analyses (XRD, TEM, and SEM/EDX) confirmed the formation and dispersion of S-NPs. The influence of S-NP content and gamma irradiation (50 kGy) on the mechanical performance, crosslinking characteristics, and thermal-aging resistance of the blends was systematically investigated. Compared with the pristine NBR/PVC blend, the incorporation of S-NPs significantly enhanced tensile strength from 2.75 MPa to 6.56 MPa and 6.38 MPa for blends containing 0.5 and 2 phr of S-NPs, respectively, under irradiation. After thermal aging at 100 °C, the tensile strength reached up to 9.10 MPa for S-NP-based vulcanizates. Equilibrium swelling decreased from 270% to 120% before irradiation and from 255% to 105% after irradiation, consistent with increased crosslink density and improved mechanical performance. Furthermore, gamma irradiation synergistically enhanced the material properties, as evidenced by the reduced swelling percentage with the increasing S-NP content, indicating higher crosslink density. The blends also exhibited strong resistance to thermal aging at 100 °C and to brake oil, making S-NP-vulcanized NBR/PVC blends suitable for applications in the production of model car tires and footwear, combining the flame resistance of PVC with the flexibility of NBR.