Relationship between the aging thermal oxygen and mechanical properties of nitrile butadiene rubber reinforced by RD-loaded carboxylated carbon nanotubes

A novel functional carbon nanofiller CNTs-COOH-RD resistant to thermal-oxidative aging was prepared by grafting 1,2-dihydro-2,2,4-trimethyl-quinoline (antioxidant RD) onto the surface of carboxylated carbon nanotubes (CNTs-COOH) using gamma-(2,3-epoxypropoxy) propytrimethoxysilane (KH560). Five groups of nitrile butadiene rubber (NBR) composites were prepared by mechanical blending, and the effects of CNTs-COOH-RD on the mechanical and tribological properties of NBR composites were investigated. The results showed that compared to pure NBR and free antioxidant RD-loaded samples, the tensile and tear strengths increased by approximately 23%, 5%, 18%, and 4%, respectively. The wear surfaces of the NBR composites were characterized using scanning electron microscopy and X-ray energy spectroscopy, which revealed the reinforcing mechanism of CNTs-COOH-RD. Molecular dynamics simulations were used to explain the thermal-oxidative aging mechanism of CNTs-COOH-RD from an atomic mechanism perspective. The results showed that the mobility of CNTs-COOHRD within the NBR matrix was significantly reduced compared with that of the free antioxidant RD. The proposed functional carbon nanofiller enabled the NBR composites to exhibit superior mechanical and thermaloxidative aging properties during the aging failure process.