The thermal-oxidative aging (TOA) and tribological properties of rubber had attracted attention in the petrochemical field. In this study, the mechanical and tribological properties of defect-free, Stone-Wales (SW), and single adatom (SA) defective carbon nanotubes (CNTs)/nitrile butadiene rubber (NBR) composites were investigated using molecular dynamics simulations. Poly (1,2-dihydro-2,2,4-trimethyl-quinoline) (antioxidant RD) was added to the composites to analyze their TOA mechanisms. Antioxidant RD provided the best protective effect in SW-CNTs/RD/NBR composites, and their TOA properties were enhanced. In addition, the Young's modulus, bulk modulus, and shear modulus, friction coefficient, and wear rate of the SW-CNTs/RD/NBR composites were improved. The effects of SW-CNTs on the RD/NBR composites were elucidated from a molecular perspective. The surface structures of three groups of CNTs were analyzed, and the SW-CNTs exhibited a stronger adsorption ability and binding effect. It was determined that the antioxidant RD and NBR could be more stably dispersed between the molecular chains in the SW-CNTs/RD/NBR composites.

Nitrile butadiene rubber (NBR), a common material used in the stator rubber of screw pumps, usually undergoes severe thermal‐oxidative aging and wear at various temperatures and pressures. In this study, 1,2‐dihydro‐2,2,4‐trimethylquinoline (antioxidant RD) and carbon nanotubes (CNTs) were introduced into NBR to improve its thermal‐oxidative aging performance and reduce its wear. The thermal‐oxidative aging and mechanical and tribological properties of NBR composites with acrylonitrile (ACN) contents of 28%, 33%, and 41% were investigated via molecular dynamics simulations, and the interaction mechanisms of four composites: RD/N28, CNT/RD/N28, CNT/RD/N33, and CNT/RD/N41, were investigated at the atomic level. A three‐layer model (Fe–Composites–Fe) was developed to simulate the wear process of the composites. CNT/RD/N41 exhibited better thermal‐oxidative aging and tribological properties than those exhibited by CNT/RD/N28 and CNT/RD/N33. This was attributed to an increase in the polar–polar interactions of the nitrile (CN) groups with an increasing ACN content. During friction, a larger frictional force existed between the CNT/RD/N41 molecules, which effectively maintained the stability of the matrix. This study provides a scientific reference for the preparation of high‐performance NBR at the microscopic scale, which may extend the service life of screw pumps.

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Nitrile rubber (NBR) is commonly used as a stator rubber for screw pumps because of its excellent mechanical properties. However, under high‐temperature conditions, using NBR for long‐term operations is difficult, since it is highly susceptible to a thermal‐oxidative aging phenomenon that leads to its failure. In this study, the thermal‐oxidative aging behavior of graphene and graphene oxide (GO) in an NBR composite system was investigated using simulated molecular dynamics at 298 K and 348 K. The results showed that Young's moduli of graphene/NBR and GO/NBR composite systems were enhanced by about 33% and 44%, respectively, when the temperature was increased. That is, adding graphene and GO improved the resistance of NBR composites to elastic, bulk, and shear deformation, playing an important role in slowing down the thermal and oxygen aging of rubber. Furthermore, the binding energy, mean square displacement, and free volume fraction of the NBR composite systems were analyzed. The abundant oxygen‐containing functional groups in GO increased the intermolecular interaction force between GO and NBR and effectively inhibited the migration of antioxidants 4020. Therefore, GO retards the thermal and oxygen aging of NBR composite systems more effectively.