On morphology of consolidated UHMWPE resin in hip cups

The microstructure of replacement hip cups made from ultra-high molecular weight polyethylene (UHMWPE) has been revealed by permanganic etching to bring out the fine details. Specimens are examined by optical microscopy according to the Nomarski technique, and by scanning and transmission electron microscopy. In all cups the original reactor particles are visible. Optical microscopy is most productive in revealing variations not only in the texture of different individual particles, but also in the degree of consolidation of a particle with its neighbours. Both these factors differ according to the material and process. Electron microscopy reveals the existence of pockets of lower molecular weight material which has been expelled from the particles by the original sintering process.