Fabrication of a novel chitosan‐based macromolecular antioxidant and its effects on the anti‐aging properties of styrene‐butadiene rubber/silica composites

Abstract In this work, a novel chitosan‐based macromolecular rubber antioxidant (denoted as COS‐AO) was successfully synthesized by using chitosan (COS) and 3‐(3,5‐di‐tert‐butyl4‐hydroxyphenyl) propionic acid (antioxidant, AO) via esterification reaction. The FTIR, 1 H NMR, 13 C NMR, and elemental analysis measurements were used to confirm the structure of COS‐AO. The performance of COS‐AO as a macromolecular antioxidant for styrene‐butadiene rubber (SBR)/silica composites were examined by oxidation induction time (OIT) test, methanol extraction experiments, accelerated thermo‐oxidative aging tests as well as thermogravimetric (TG) test. The results indicated that the macromolecular antioxidant COS‐AO presented better extraction resistance and migration resistance in SBR/silica composites compared to the small molecular antioxidant AO. Moreover, COS‐AO significantly improved the thermal stability as well as the value of the oxidation induction time of SBR/silica composites, exhibiting superior thermo‐oxidative aging resistance. In addition, the potential antioxidative mechanism of COS‐AO in SBR/silica composites was also discussed.