Mechanisms of static and kinetic friction of polypropylene, polyethylene terephthalate, and high-density polyethylene pairs during sliding

Polymeric materials are widely used in household applications. During use, sliding surfaces are worn out and the interfacial properties change affecting friction. Consequently, understanding of friction mechanisms of polymeric materials with changing interfacial properties is important. In this study, the effect of various speed, load, and dwell time conditions on friction of polypropylene (PP), polyethylene terephthalate (PET), and high-density polyethylene (HDPE) pairs is studied. Roughness, debris formation, and mechanical properties are measured to understand friction behavior. Static and kinetic friction exhibits dependence on surface roughness which affects mechanical interaction of asperities and real contact area. Static friction increases with dwell time due to creep.