A comparative study on enhancement of mechanical and tribological properties of nitrile rubber composites reinforced by different functionalized graphene sheets: Molecular dynamics simulations

摘要

Molecular dynamics (MD) simulations were adopted to compare the enhanced mechanical and tribological properties of nitrile rubber composites reinforced by different functionalized graphene sheets. Functional groups such as hydroxyl (-OH), carboxyl (-COOH), and ester (-COOCH3) were adopted. The constant strain method was applied to measure the mechanical properties of graphene/nitrile rubber composites. Sandwiched molecular models were developed to investigate the tribological properties of graphene/nitrile rubber composites by applying a shear load. The MD simulation results showed that the incorporation of functionalized graphene enhanced the Young's modulus, bulk modulus, and shear modulus of the nitrile rubber matrix. In addition, the coefficient of friction and abrasion rate of the functionalized graphene/nitrile rubber composites decreased. The mechanisms for the interfacial interactions between the functionalized graphene and nitrile rubber matrix were determined by calculating the mean square displacement of rubber chains, binding energy, and the radial distribution function between functional groups and polar atoms in the rubber matrix, respectively. The results of the atomistic simulations indicated that stronger interfacial interactions and better stability and dispersion of graphene in rubber matrices can be obtained by introducing functionalized graphene. Owing to the combination of hydrogen bonding and strong van der Waals interactions, the COOH-functionalized graphene behaves the best effect on the enhancement of mechanical and tribological properties of the nitrile rubber composites.