Sliding Experiments with Polytetrafluoroethylene

The sliding of polytetrafluoroethylene (PTFE) was experimentally examined with a sled type apparatus and with a conventional three pins-on-flat frictometer. Friction hysteresis and time-and speed-dependent phenomena were observed with both instruments and were compared. With the sled apparatus, the relation between friction and sliding speed of PTFE sliding on PTFE at different ambient temperatures was examined and is described. A study of the sliding surface of PTFE with the electron microscope was made. The initial results give clear photographic evidence in stereo that films and fibers of PTFE are stretched and drawn over relatively large distances across the topography of the sliding surface. In view of this and the viscoelastic nature of polymer deformation, the observed time and temperature dependence of friction becomes plausible. Presented at the ASLE Annual Meeting in Cleveland, May 6–9, 1968.