The mechanism of friction deposition of polytetrafluoroethylene (PTFE) and polyethylene (PE) was studied by scanning electron (SEM) and scanning force microscopy (SFM) on the worn surfaces of PTFE and PE sliders that were used in friction deposition on glass substrates. These surfaces exhibited a fibrillar morphology which was oriented in the sliding direction. The molecular order of the PTFE and PE chains on the surface of thin microfibrils on the slider could be readily imaged with molecular resolution using SFM. The SEM and SFM images present direct evidence of an orientation of the slider on both a fibrillar and a molecular level and thus support the orientation mechanism postulated by Pooley and Tabor (Proc. R. Soc. London A, 1972, 329, 251). The orientation occurs during shearing of the material that sticks to the glass surface due to the high adhesion between the first layer of PTFE and the glass.
- Scanning force microscopy