Preparation of Sepiolite‐Based Rubber Antioxidants and Their Performance in Natural Rubber Composites

Natural rubber (NR) is highly susceptible to thermo‐oxidative degradation, and conventional low‐molecular‐weight antioxidants suffer from migration and volatilization, limiting long‐term durability. In this study, a sepiolite‐based antioxidant system was developed to improve antioxidant stability and aging resistance. Sepiolite was activated and loaded with N ‐isopropyl‐ N ′‐phenyl‐ p ‐phenylenediamine (IPPD) via vacuum‐assisted impregnation, and the resulting hybrid filler was incorporated into NR through an aqueous latex compounding process. Structural and compositional analyses using FTIR, XPS, TGA, and SEM confirmed successful IPPD immobilization within sepiolite, achieving a maximum loading of 7.71 wt%. The sepiolite‐based antioxidant exhibited improved dispersion and interfacial compatibility in the NR matrix, enhanced cross‐linking characteristics, and reduced antioxidant migration. Compared with directly added IPPD, composites containing Sep‐IP showed superior thermo‐oxidative aging resistance and thermal stability, even with a reduced antioxidant dosage. These improvements are attributed to the sustained release effect and reinforcing function of sepiolite. This study demonstrates that sepiolite can serve as an effective multifunctional carrier for antioxidants, providing a sustainable strategy to enhance the durability and long‐term performance of rubber composites.