A Molecular Dynamics Simulation Study on Mechanical and Tribological Properties of SBR Composites Strengthened by Surface‐Modified Silica

ABSTRACT The interfacial enhancement mechanism has always been a widely concerned issue in the preparation of high‐performance silica‐reinforced rubber nanocomposites. In this study, the influence of the substitution of hydroxyl groups on the surface of silica (SiO 2 ) by carboxyl groups on the mechanical and tribological capacities of styrene‐butadiene rubber (SBR) composites was studied through molecular dynamics (MD) simulations. Results display that compared with the original SiO 2 nanoparticles, the carboxyl‐substituted SiO 2 nanoparticles can effectively reinforce the interface strength between SiO 2 nanoparticles and SBR; that is, the synergistic effect of the interfacial interaction strength and the interfacial interlocking effect dominated by the surface roughness leads to a remarkable improvement in the mechanical and tribological performances of SBR composites. In particular, compared with the original SiO 2 nanoparticles, in normal separation mode, the interfacial cohesion strength and interfacial fracture toughness between the 100% carboxyl‐substituted SiO 2 nanoparticles and the SBR matrix are improved by 16.05% and 29.11%, respectively; in shear separation mode, the interfacial shear strength and interfacial fracture toughness between the 100% carboxyl‐substituted SiO 2 nanoparticles and the SBR matrix are increased by 36.92% and 71.72%, respectively.