Molecular Dynamics Simulation of Mechanical and Tribological Properties of Ultrahigh Molecular Weight Polyethylene Enhanced by Modified Silica Nanoparticles

Silica nanoparticles have been proved to be one of the effective methods to improve the tribological properties of ultrahigh molecular weight polyethylene (UPE). However, the tribological mechanisms have not been clarified. Herein, the mechanical and tribological properties of UPE were improved by grafting silica with KH550, KH560 and KH570, respectively. The molecular dynamics simulation was used to study the binding energies of nano-silica and UPE, and temperature distribution, atomic relative concentration distribution and radial distribution function value of UPE and copper atomic layer along the thickness direction during the friction process. The results showed that the silica grafted with coupling agent can improve the shear modulus and decrease the wear rates of materials. Compared with that of UPE, the shear modulus of KH560 grafted nano-silica-modified UPE was increased by 98.2%, and wear rate was decreased by 68.6%. The research provides a technical guidance for the water-lubricated bearing of UPE modified by nano-silica.