Effect of Geometrical Defects of Boron Nitride Nanotubes on Mechanical and Tribological Properties of Nitrile Butadiene Rubber Composites: Molecular Dynamics Simulations

ABSTRACT Understanding the role of surface defects in nanoparticles is crucial for optimizing the interfacial design of polymer composites. In this study, molecular dynamics (MD) simulations were employed to investigate the influence of geometrical defects in boron nitride nanotubes (BNNTs) on the mechanical, interfacial, and tribological properties of nitrile butadiene rubber (NBR) matrices. Results reveal that defect‐free BNNTs provide the most effective reinforcement of the tensile properties of NBR, followed by Stone–Thrower–Wales (STW)‐defective BNNTs, whereas di‐vacancy (DV)‐defective BNNTs only have an obvious enhancement effect on the elastic modulus of NBR. Pull‐out simulations further demonstrate that, compared to DV‐ and STW‐defective BNNTs, defect‐free BNNTs enhance the interfacial shear strength and interfacial fracture toughness of NBR composites by 21.2% and 5.96%, and 22.5% and 5.14%, respectively. Additionally, compared with neat NBR, the incorporation of defect‐free, DV‐defective, and STW‐defective BNNTs reduces the friction coefficient and abrasion rate by 1.92% and 18.36%, 3.69% and 17.24%, and 3.97% and 17.84%, respectively. To elucidate the underlying mechanisms of BNNT surface defects, detailed analyses of the structural evolution of the composite networks and interfacial states were conducted. Overall, these findings provide new insights into the defect‐mediated reinforcement behavior of BNNTs and offer guidance for the rational design of defect‐engineered nanofillers to improve the performance of polymer composites.