Roles of Size, Shape, Amount, and Functionalization of Nanoparticles of Titania in Controlling the Tribo-Performance of UHMWPE Composites

Abstract

The present research is based on development and performance evaluation of ultra-high molecular weight polyethylene composites with Titania particles in various amounts and of two sizes, including nano-size. It also included functionalization of nanoparticles (NPs) with a siloxane group to enhance adhesion with the matrix, which would help to reduce wear. Thus, the work had several objectives such as to investigate the effect of size (nano vs. micro) and determine the amount that delivers the best performance from among a series of composites with different Titania particle amounts [0–8% in the case of microcomposites (MCs) and 0–4% in the case of nanocomposites (NCs)]. It was also of interest to examine the effect of siloxane-functionalization of NPs [since they performed significantly better than microparticles (MPs)] on the performance of NCs. It was observed that for adhesive and erosive wear modes, both types of particles (MPs and NPs) proved detrimental in spite of the enhanced hardness of the composites, essentially because of the irregular shape of particles, which altered the wear mechanisms adversely. Nanoparticles proved less detrimental, while F-NPs (functionalized NPs) proved marginally detrimental. In abrasive wear mode, both proved beneficial, NPs being more effective than MPs, and F-NPs proved the best. The studies revealed how the shape of particles influences the performance of composites in various wear modes.