THE MECHANISM OF PTFE AND PE FRICTION DEPOSITION - A COMBINED SCANNING ELECTRON AND SCANNING FORCE MICROSCOPY STUDY ON HIGHLY ORIENTED POLYMERIC SLIDERS

The mechanism of friction deposition of polytetrafluoroethylene (PTFE) and polyethylene (PE) was studied by scanning electron (SEM) and scan ning force microscopy (SFM) on the worn surfaces of PTFE and PE slider s that were used in friction deposition on glass substrates. These sur faces exhibited a fibrillar morphology which was oriented in the slidi ng direction. The molecular order of the PTFE and PE chains on the sur face of thin microfibrils on the slider could be readily imaged with m olecular resolution using SFM. The SEM and SFM images present direct e vidence of an orientation of the slider on both a fibrillar and a mole cular level and thus support the orientation mechanism postulated by P ooley and Tabor (Proc. R. Sec. London A, 1972, 329, 251). The orientat ion occurs during shearing of the material that sticks to the glass su rface due to the high adhesion between the first layer of PTFE and the glass. (C) 1998 Elsevier Science Ltd. All rights reserved.