A polytetrafluoroethylene filled ultra-high molecular weight polyethylene composite: Mechanical and wear property relationships

This research addresses the wear properties and processes of 10 vol% polytetrafluoroethylene (PTFE) filled ultra‐high molecular weight polyethylene (UHMWPE) composites and their relationship to mechanical properties. The addition of the PTFE micropowder results in a slight increase in modulus and a significantly lower strain at break. This is due to a quasi‐brittle failure mechanism. Crosslinking the UHMWPE reduces both the modulus and the ultimate properties. Polymer wear studies against SiC abrasive paper can be divided into initial and steady‐state processes. The initial wear, polymer‐SiC wear, is dominated by microcutting and the formation of a transfer film. A single‐pass wear rate (R1) can be derived from a power‐law description of the initial wear. The steady‐state wear eventually achieved, called polymer‐film wear, is dominated by sliding against a self‐generated. A steady‐state multiple‐pass wear rate (Rx) can be derived from a linear description of steady‐state wear. The relationships between the wear of UHMWPE and the wear of PTFE can be predicted through their ultimate and deformation properties and through an understanding of the wear mechanisms. These relationships cannot be used to relate composite and UHMWPE wear due to their different failure mechanisms. The lower Rx and coefficient of friction of the composite may be related to the PTFE flakes found on the worn and wearing surface. Crosslinking the UHMWPE yields little change in the worn and wearing surfaces and in Rx. The increase in R1 on addition of PTFE and decrease in R1 on crosslinking may be related to the respective increase and decrease in modulus.