Natural rubber composites with antioxidant‐loaded activated calcium silicate for improved thermo‐oxidative aging resistance

Abstract

AbstractGreen and low‐cost methods are required as alternatives to conventional approaches for impeding the thermo‐oxidative degradation of natural rubber (NR). Herein, to improve the dispersibility of N‐1,3‐dimethylbutyl‐N′‐phenyl‐p‐phenylenediamine (antioxidant 4020) and simplify the loading procedure, antioxidant 4020 was precipitated from acetone using activated calcium silicate (ACS), a byproduct of alumina extraction from fly ash, as a carrier. In the obtained antioxidant 4020‐loaded ACS (ACS‐4020) particles, which had a loading of 7.8%, the antioxidant was physisorbed on the surface of ACS with a uniform distribution. In composites with NR, ACS‐4020 was uniformly dispersed in the NR matrix via chemisorption. ACS‐4020/NR exhibited a faster vulcanization speed, better static mechanical properties, and greater thermal stability than the composite in which antioxidant 4020 was directly integrated (ACS/4020/NR). Changes in the tensile strength, elongation at break, hardness, and thermo‐oxidative aging degree of the composites at different aging times and temperatures showed that ACS‐4020/NR had enhanced resistance to thermo‐oxidative aging. Furthermore, the nitrogen‐containing compounds in ACS‐4020/NR were more stable and performed better against thermo‐oxidative aging. These findings can act as guidelines for the preparation of NR composites with superior thermo‐oxidative aging resistance.