Abstract:

To address the susceptibility of natural rubber (NR) to oxidative aging arising from highly reactive sites such as double bonds and α-hydrogens in its molecular structure, this study designs and prepares a supported long-term sustained-release antioxidant system (4010NA@DE) with a three-level “load-coat-graft” functional architecture based on diatomite (DE). The antioxidant N-isopropyl-N'-phenyl-p-phenylenediamine (4010NA) is first loaded onto diatomite, followed by surface coating with polydopamine, and subsequent grafting of flexible oleylamine chains. This hierarchical design effectively suppresses migration of small-molecule antioxidants within the natural rubber matrix while improving interfacial compatibility, thereby mitigating issues of blooming and rapid depletion associated with conventional antioxidants. Experimental results show that NR composites incorporating 4010NA@DE exhibit excellent anti-aging performance. After 672 h of thermo-oxidative aging at 100 ℃, the tensile strength remains above 20 MPa and the elongation at break exceeds 450%, with no observable surface blooming. The retention rates of tensile strength and elongation at break reach 81% and 68%, respectively, with an aging coefficient of 0.56. This work provides a viable strategy for designing durable, migration-resistant antioxidant systems for long-term protection of rubber materials.

Key words: natural rubber, diatomite, supported antioxidant, anti-aging performance