Evolution of the microstructure of amorphous polyethylene under friction-induced plastic flows: A reactive molecular investigation.

This article investigates the plastic flow and wear mechanisms of ultra-high molecular weight polyethylene (UHMWPE) at frictional interfaces using reactive molecular dynamics simulations, focusing on interactions with iron (Fe) surfaces. It reveals that during friction, polyethylene (PE) chains undergo plastic deformation characterized by detachment, cavitation formation, and molecular rearrangement, which are intensified by convex protrusions on the Fe surface causing plowing effects. The study further shows that C–C covalent bonds in PE chains break after full stretching, producing short alkyl radicals that chemically bond to the Fe surface, contributing to transfer film formation and surface reconstruction. These molecular-level insights elucidate the evolution of interfacial microstructure and provide a deeper understanding of UHMWPE wear behavior relevant to applications such as artificial joints and bearing materials.