Application of sorbic acid in situ modified steel slag filler in natural rubber composites and its mechanism of heat and air aging resistance properties

Abstract Steel slag, a solid waste from steelmaking, accounts for about 20% of steel production. Its huge production, along with extreme storage and treatment difficulties, negatively impacts the environment. With excellent wear resistance, high modulus, and large porosity, steel slag could have a wide application range if utilized rationally. This study aims to replace carbon black, the traditional reinforcing filler for rubber, with in situ modified steel slag using sorbic acid. The results show that the steel slag can be incorporated into the rubber composite through in situ modification. The vulcanization performance of the rubber composite is improved, the interaction between the filler and the rubber molecular chain is enhanced, and the flexibility of the rubber molecular chain crosslinking network is strengthened. Meanwhile, the mechanical properties are maintained with a reasonable modified steel slag addition. Thermo‐oxidative aging experiments reveal that adding modified steel slag generates unsaturated carboxylate nanoclusters that significantly improve the performance retention rate of the rubber material while enhancing its aging resistance. In summary, modified steel slag can serve as a filler in rubber materials. This study constitutes a meaningful exploration into the harmless treatment of steel slag and its environmental pollution, offering a new method and theoretical support for its recycling and reuse. Highlights In‐situ modification of steel slag filler by sorbic acid. Generation of dynamic ionic crosslinking network. Sorbic acid metal salt reinforcing rubber. Hot air aging promotes nanocrystal production. Sorbic acid metal salt nanoclusters to improve aging resistance.