Preparation of Epoxidized Natural Rubbers with Improved Aging Resistance by Covalently Bridging Graphene and Antioxidants

A new kind of epoxidized natural rubber (ENR) nanocomposites with enhanced aging resistance by the inclusion of a non-migratory anti-aging agent was prepared. The non-migratory anti-aging agent was obtained by immobilizing antioxidant molecules on graphene oxide (GO) surface using a silane coupling agent. In this way, the diffusion of the small-molecule antioxidants is restricted, leading to low loss of antioxidants in rubber service and the improvement of rubber aging resistance. GO, due to its unique two-dimensional planar structure, forms barrier layers inside the composite to prevent gas diffusion, which also contributes to the enhancement in anti-aging properties. In addition, hydrogen bond networks form between ENR chains and GO nanosheets, limiting the movement of the non-migratory anti-aging agents and improve their stability in rubber matrix. Our experimental results demonstrated that the non-migratory anti-aging agents can endow rubbers with better resistance to thermo-oxidative aging than the conventional antioxidants with a same amount.