A comparative study on thermo-oxidative aging and tribological properties of perfluoroelastomer composites reinforced by different carbon nanomaterials at elevated temperatures: Molecular dynamics simulations

Abstract

Molecular dynamics (MD) simulations are employed to assess the effects of diverse carbon nanomaterials on the thermo-oxidative aging properties and tribological behavior of perfluoroelastomer (FFKM) in high-temperature environments. In this study, carbon nanofillers such as graphene nanosheets (GNS), carbon nanotubes (CNTs), hydroxyl-functionalized graphene (OH-GNS), and hydroxyl-functionalized carbon nanotubes (OH-CNTs) are examined. The aging properties of composite systems are characterized by parameters like cohesive energy density and mean square displacement. The constant strain method is utilized to estimate the shear modulus and bulk modulus. Three-layer friction structures are established to analyze the mechanism of fillers on the tribological behavior of composites by applying shear loads. According to the MD simulation results, the addition of carbon nanofillers enhances FFKM's thermo-oxidative aging performance at 533 K, increases its bulk and shear moduli, and reduces the coefficient of friction and abrasion rate of each composite at high temperatures. Among the four nanofillers, OH-CNTs is the most effective in terms of improving FFKM performance. Stronger dipoledipole interactions and hydrogen bonding are introduced into the system by OH-CNTs, which improves the stability of the filler-matrix interface and produces stronger interfacial interactions. This work offers theoretical predictions for the design and optimization of carbon nanomaterial and FFKM polymer composites.