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The wear of surgical grade ultra-high molecular weight polyethylene against stainless steel has been studied for unidirectional motion. After a short wearing-in period, two distinct steady-state regions appear on the wear graphs. In the first section adhesion is the predominant wear mechanism and a transfer film of polymer builds up on the steel counterface. After a certain sliding distance, determined by the load, the adhesive mechanism is augmented by fatigue wear and the wear rate increases sharply and remains constant at the new value.

Various aspects of adhesion play significant roles in digital printing, especially when electrophotographic technology is employed. This paper will concentrate on the adhesion and removal of toner particles, the marking particles used in the electrophotographic process. Two forces govern the adhesion and cohesion of toner particles -electrostatics and van der Waals. These forces must be carefully controlled in order to consistently and robustly achieve the desired image quality on the surface of the print. After transferring the toner particles to paper, the image must be fixed by subjecting the toner to heat and pressure, thereby transforming polymeric toner particles into a hot-melt adhesive. This paper discusses the physics and chemistry used to control toner adhesion, the constraints of toner adhesion on the design and performance of subsystems, and the impact on image quality and the marking engine if toner adhesion and cohesion are not properly controlled.