Molecular simulation of the effect of dioctyl phthalate on the properties of nitrile rubber

Abstract

The mechanical and tribological properties of pure nitrile rubber (NBR) and dioctyl phthalate/nitrile rubber (DOP/NBR) composite materials with mass ratios of 5/95, 10/90, 15/85, 20/80, 25/75, and 30/70 were studied through molecular dynamics simulations at the molecular level. The root mean square displacement (RMSD) and gyration radius of the composite materials were investigated to explore the mechanism of DOP plasticizing NBR. Different models of pure NBR and DOP/NBR composite materials with different mass ratios were established, and the mechanical properties of the materials were calculated by using the constant strain method. The tribological properties of the materials were studied by applying shear velocity on the surface of the materials. The research results showed that the shear resistance of the DOP/NBR composite material increased and then decreased with the increase of the DOP mass ratio, and the same pattern was observed for the shear modulus. Compared with pure NBR materials, DOP/NBR composite materials demonstrated better mobility and flexibility, and the RMSD and gyration radius of the material increased and then decreased with the increase of the DOP mass ratio. The DOP plasticization of NBR reduced the intermolecular interaction forces and changed the molecular conformation, increasing the softness and plasticity of the polymer chains.