Experimental and Molecular Dynamics Insights Into the Structure–Property Relationship and Tribological Mechanisms of h‐ BN Modified PI /

ABSTRACT

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.