Study on the Thermal‐Oxidative Aging Resistance of Natural Rubber Composites Reinforced With Curcumin‐Grafted Silica

ABSTRACT

To mitigate the environmental pollution and health hazards associated with traditional amine antioxidants and align with the trend toward sustainable rubber additives, a biomass‐based functional filler with both antioxidative and reinforcing properties was prepared via a chemical grafting process using the natural phenolic compound curcumin. Using DBTDL as a catalyst, curcumin was successfully grafted onto the silica surface with an effective loading rate of 11.5%. Upon incorporating this functionalized filler into the silica/NR composites, the Payne effect of the filler network was significantly reduced, indicating a uniform dispersion of the filler within the rubber matrix and improved filler‐matrix compatibility. Experimental results, including thermo‐oxidative aging tests, crosslink density retention, and oxidation induction time, demonstrated that compared to silica/NR composites containing directly blended curcumin, the composites exhibited significantly enhanced mechanical properties and thermo‐oxidative aging resistance. Specifically, the optimized composite exhibited a comprehensive aging coefficient of 0.68, a high crosslink density retention of 0.97, an extended OIT of 10.7 min, and T _max in air delayed to 360.1°C. Furthermore, their aging resistance was comparable to that of the conventional antioxidant 6PPD formulation system. These findings indicate that immobilizing curcumin onto the silica surface via a chemical grafting strategy serves as a promising eco‐friendly alternative for thermo‐oxidative protection, reducing the reliance on traditional amine antioxidants in silica/NR composites. This study provides a novel design strategy for the development of efficient, eco‐friendly, and multifunctional green anti‐aging systems for rubber.