Multi-Mechanistic Bio-Based Antioxidants Constructed by Polyphenol-Thiourea-Rare Earth Synergy on Enhancing Thermo-Oxidative Aging Resistance of NBR

To address the challenges encountered by conventional antioxidants, such as migration, toxicity, and single aging resistance mechanisms, which fail to meet the demands for high performance and sustainability. In this study, a series of multi-mechanistic bio-based antioxidants (PDTA-RE) featuring polyphenol-thiourea-rare earth synergy were designed through a sequential “polymerization-grafting-complexation” strategy. Then, the thermo-oxidative aging resistance of composites was evaluated via 121 °C accelerated aging tests, thermal analysis, and kinetic analysis of thermal-oxidative decomposition. Following 120 hours of aging, the PDTASc/NBR composites exhibited a tensile strength retention rate of 93.63% and an aging coefficient ( K ) of 0.61, which were 79.85% and 258.82% higher than those of Neat/NBR, respectively, while superior to commercial antioxidants. Moreover, polyphenolic groups scavenge free radicals, thiourea mercapto decompose hydroperoxides, and rare earth ions trap residual radicals. Additionally, the polymerized framework and double bond anchoring endowed PDTA-RE with excellent anti-migration ability, avoiding high-temperature efficacy loss.