Experimental and Molecular Dynamics Insights Into the Structure–Property Relationship and Tribological Mechanisms of h-BN Modified PI/CF/MoS2 Composites

Polyimide (PI)-based tribological composites containing carbon fiber (CF), molybdenum disulfide (MoS 2 ), and other solid lubricants have been extensively studied. However, the role of hexagonal boron nitride (h-BN) in regulating interfacial interactions and wear mechanisms in PI/CF/MoS 2 systems remains insufficiently understood. In this study, the effects of h-BN incorporation on the mechanical and tribological behaviors of PI/CF/MoS 2 composites were systematically investigated through experimental characterization combined with molecular dynamics (MD) simulations. The results revealed that h-BN addition improved hardness while reducing tensile strength and ductility due to the enhanced interfacial restriction and increased stress concentration. The tribological performance exhibited a non-monotonic dependence on h-BN content, with the optimal performance achieved at 5 wt.% h-BN. Scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) analyses suggested that an appropriate h-BN content facilitated the formation of a relatively continuous transfer film, whereas excessive h-BN promoted filler agglomeration and interfacial degradation, leading to accelerated wear. Furthermore, MD simulations suggested that the reduced molecular mobility and fractional free volume at the optimal h-BN content were consistent with enhanced interfacial stability. The combined experimental and simulation results provide qualitative insights into the role of h-BN in regulating filler dispersion, interfacial interactions, and molecular chain dynamics. These findings establish a structure–property relationship for designing high-performance multi-filler PI-based tribological composites. Highlights Hexagonal boron nitride improves the hardness but reduces tensile strength. Friction and wear are minimized at 5 wt.% hexagonal boron nitride loading. Excess hexagonal boron nitride triggers agglomeration and abrasive wear. Molecular dynamics simulations corroborate experimental wear mechanisms.