SUBMICRON-SCALE INDENTATION AND CHARACTERISATION OF ORTHOPEDIC POLYMERS: THE EFFECT OF CROSSLINK DENSITY AND MORPHOLOGY ON THE HARDNESS AND ELASTIC PROPERTIES OF POLYETHYLENE

摘要

The effect of crosslink density, oxygen ion implantation, and crystalline morphology on the hardness and elastic modulus of ultra-high molecular weight polyethylene (UHMWPE) were investigated in light of indentation results obtained with a 20 μm radius diamond tip and indentation loads in the range of 75-600 μN. Flat specimens of UHMWPE crosslinked with varying amounts of ionizing radiation were ion implanted with oxygen at two different doses. Indentations were also performed on low-density polyethylene (LDPE) and high-density polyethylene (HDPE) in order to determine the effect of crystalline morphology on the local hardness and elastic properties. The results of this work demonstrate that submicron-scale indentation is a novel method for measuring the mechanical properties of various polyethylene materials at submicron levels.