Review: Tribological behavior of polyethylene-based nanocomposites

Thermoplastics polyethylene (PE) materials, such as high density polyethylene (HDPE) and ultra high molecular weight polyethylene (UHMWPE), are widely used as bearing materials in industrial applications. UHMWPE, with its superior wear resistance and low-friction surface properties, has also been applied successfully as a key material in artificial knee and hip joint replacements. However, the wear debris generated during the joint motions could cause osteolysis and loosening of the implant, contributing to the main cause for joint revision. Many attempts have been made to improve the wear resistance of PE materials in order to elongate the material’s service life. Various nano-fillers, including carbon nanofibers, carbon nanotubes, nano-alumina, and nano-montmorillonite, have been applied as ideal reinforcing components to modify the tribological properties of PE. This article reviews the current status of research in tribological studies of PE-based nanocomposites, mainly UHMWPE and HDPE nanocomposites, including the types of nano-fillers, fabrication methods, and tribological characterization approaches. The dependence of tribological properties of those nanocomposites on the concentrations and modifications of nano-fillers, and other tribological parameters is summarized; the different wear mechanisms are reviewed. New research directions in this field are proposed.