On the nanotribology of polyethylene single crystals

Polyethylene has been used as a bearing surface in numerous applications for in excess of four decades. The semi-crystalline structure of this material has been proposed to have fundamental influence over its wear characteristics; however, reports considering its crystalline phase are sparse. Nanotribological measurements on supported polyethylene single crystals (PESCs) were conducted using lateral force microscopy (LFM). It was observed that the amorphous thin layer on the surface of PESC made a significant contribution to their tribological behaviour. At modest contact stresses, repeated scans on the surface of a single crystal induced changes in sliding friction due to modification of the PESC's structure but in the absence of wear. At high contact stress, material removal and nano-particle production was observed. The results are indicative of the role of both the crystalline lamellae and amorphous domains within the PESC in the wear and nano-particle debris production of the bulk semi-crystalline polyethylene.