MICROTRIBOLOGY OF PET POLYMERIC FILMS

Atomic force microscopy (AFM) and friction force microscopy (FFM) are used to conduct microtribological studies of thin polyethylene terephthalate (PET) films which ale commonly used in many industrial applications including as a magnetic tape substrate. In the PET films, microscale friction values are found to be smaller than macrofriction values. Local variation in microscale friction is found to correspond to the local slope which suggests that a ratchet mechanism is responsible for this variation. There is also a directionality effect in the local variation of microfriction. Microwear tests are also reported. The polymeric material tears in microwear tests. Ceramic particles added to the PET films as an anti-slip agent, affect the microfriction values, scratch depth and wear depth. For the polymeric material, scratch depth and wear depth increase approximately linearly with an increase in the normal load and test duration. Nanoindentation behavior and nanohardness values of the films vary from one location to another because of ceramic particles being present on ol below the film surface. AFM is found to be a useful technique for microtribological and nanomechanical property measurements of these thin films.