Relationship between vulcanization temperature and mechanical/friction properties of nitrile butadiene rubber composites: From molecular dynamics simulation to macroscopic testing

The properties of nitrile butadiene rubber (NBR) composites are non-monotonically governed by the vulcanization temperature, which tailors their molecular network structure. This study employed a combined approach of macroscopic experiments and molecular dynamics (MD) simulations to identify a performance optimum at 160 °C. At this temperature, the composite attained a peak crosslink density, which underpinned its superior thermal stability, tensile strength (17.27 MPa), and fatigue resistance. The morphology of the worn surface transitioned from severe abrasion at other temperatures to a smooth profile at 160 °C, corresponding to the minimum observed friction coefficient. The MD simulations revealed that this excellence originated from a synergistically stabilized microstructure at the optimal Vulcanization conditions as evidenced by the strongest intermolecular interactions (bond and angle energy), most favorable component compatibility (lowest solubility parameter difference), and most restricted molecular chain mobility (lowest mean square displacement). In conclusion, these multi-scale insights establish vulcanization temperature as a critical, microstructure-governing processing parameter for the design of high-performance rubber composites.