Molecular Dynamics Simulation of PP/UHMWPE Blends: Effects of Component Regulation on Rheological, Mechanical, and Friction-Wear Properties

Ultrahigh-molecular-weight polyethylene (UHMWPE), due to its extremely high melt viscosity and poor processing fluidity, severely restricts the forming and processing of the material and its application in engineering scenarios. Therefore, improving its processability while maintaining its excellent wear resistance has become a key scientific issue in the application of this material. In this study, polypropylene (PP) was used as a modification phase, and molecular dynamics simulation methods were employed to investigate the steady-state shear rheological, tensile mechanical, and friction-wear properties of PP/UHMWPE blend systems, revealing the regulatory mechanism of PP on the microstructure and macroscopic properties of UHMWPE. The results show that all blend systems exhibit shear thinning behavior, and the melt viscosity decreases significantly with increasing PP content. The blend systems are thermodynamically partially compatible. The 10/90 system exhibits optimal chain segment motion synergy, tensile strength, and structural stability, with an effective delay in microdamage evolution. As the PP content increases from 0 to 50%, the wear resistance of the material decreases and the wear rate increases from 36.96 to 58.42%. At the molecular level, PP reduces nonbonded interactions, lowers the entanglement density, and enhances chain mobility, thereby improving processability. However, excessive reduction in entanglement weakens the load transfer and decreases wear resistance. Thus, an appropriate PP content achieves a balance between a reduced viscosity and maintained mechanical performance. The PP/UHMWPE (10/90) system achieves the best synergy among the processing fluidity, mechanical strength, and wear resistance.