Enhancing the Properties of Devulcanized Natural Rubber Through Sulfur Revulcanization Followed by Electron Beam Postcuring

Abstract

ABSTRACT Devulcanized natural rubber (DNR) is a sustainable material with potential for circular resource utilization. This study investigated electron‐beam irradiation as a postcuring treatment for sulfur‐revulcanized DNR over a dose range of 0–500 kGy. Irradiation promoted additional crosslink formation, progressively increasing crosslink density, although the rate of increase reduced above 200 kGy, suggesting increasing competition from possible radiation‐induced chain scission. The resulting network modification enhanced thermomechanical and dynamic mechanical properties, as evidenced by increased TSSR index, storage modulus, and glass transition temperature, together with decreased tan δ. Increased crosslink density also promoted molecular orientation and shifted the onset of strain‐induced crystallization to lower strains, while the possible formation of relatively rigid CC crosslinks may further contribute to this behavior. Although modulus increased progressively with irradiation dose, optimum mechanical performance was achieved at 100 kGy, with a substantial 39% increase in tensile strength without sacrificing extensibility. Electron‐beam postcuring also improved mechanical‐property retention during thermal aging, whereas excessive irradiation, particularly at 500 kGy, caused substantial deterioration after prolonged aging. Overall, 100 kGy provided the most favorable balance between additional crosslinking and irradiation‐induced structural changes, demonstrating the potential of controlled electron‐beam postcuring for enhancing the performance and high‐value utilization of sulfur‐revulcanized DNR.