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The Flow Ratio Effect on Oriented, Crosslinked UHMWPE
King, R, Young, S., Greer, K., Hanes, M., McNulty, D., Smith, T.
Introduction
Compression molding process is known to produce UHMWPE components of improved oxidation resistance and quality surface finish. In recent years, it has been also demonstrated that it is capable of inducing molecular orientation and quenching residual free radicals in pre-irradiated UHMWPE. The objectives of this study was to evaluate the flow ratio effect on mechanical and wear properties of crosslinked UHMWPE.
Materials and Methods
Pre-irradiated GUR 1020 preforms corresponding to flow ratios from 1.06 to 1.40 were used in the flow molding process. Thermal mechanical analysis and crossed polarizer microphotography were used to verify the presence of molecular orientation in crosslinked UHMWPE. Tensile(Type V), double notched Izod and pin on disk data were generated and compared.
Results
Biaxial orientation in crosslinked UHMWPE can be attained by inducing radial elongation flow during the compression molding process of pre-irradiated UHMWPE puck. Degree of molecular orientation is related to flow ratio and is reflected in the extent of enhancement of mechanical properties. Wear data show that medium flow ratio also provide the benefit of reduced wear.
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