The Coefficient of Friction of High Polymers as a Function of Pressure.
Abstract:
Frictional behavior of low-density polyethylene, high-density polyethylene, polypropylene, polyvinylidenefluoride, PTFE, ethylene-tetrafluoroethylene copolymers, and tetrafluorethylene-hexafluoropropylene copolymers is reported. The experimental values of the coefficient of friction for each polymer agreed well with the values calculated from the pressureshear strength data, even when this data was extrapolated to higher or lower pressures. It is concluded that the coefficient of friction as a function of pressure can be determined from shear strength measurements, and conversely shear strength as a function or pressure can be estimated from friction measurements of thin films. In general, for thin polymer films, where pressures are usually high, the coefficient of friction will be determined almost entirely by the slope of the shear strength-vs-pressure curve. For bulk polymer specimens the coefficient of friction will be greatly influenced by the intercept on the shear strength axis of that curve and the hardness of the polymer. This accounts for the large difference in the frictional properties between bulk specimens of high-density and low-density polyethylene. Author, modified-PL