Influence of Radiation on Mechanical Properties of Ultra High Molecular Weight Polyethylene (UHMWPE)

Abstract

Ultra high molecular weight polyethylene (UHMWPE) is used in medicine, mainly in the acetabulum and the sliding elements of endoprosthesis. Benefits, which have determined its use is primarily a very good tribological properties, toughness, durability, resistance to biological fluids and good mechanical properties. Unfortunately UHMWPE is not free from drawbacks, which mainly include the low resistance to frictional wear a low yield strength, the tendency to creep and aging. An important issue exposed in the literature, is the change of the polyethylene physical properties by ionizing radiation, which influences the degree of crystallinity, and consequently, a decrease in mechanical properties. Therefore, the aim of the study was to determine the influence of X-rays on mechanical properties of polyethylene used for acetabula of hip endoprosthesis. The originality of the paper consists in the fact that the tested material was irradiated with the true value of radiation doses to which the patients are exposed during clinical treatment after hip replacement, in order to check their safety. Test specimens were irradiated with different X-ray doses. In the course of the study the visual inspection of the polyethylene surface, density measurement (immersion test), static tensile and bending tests as well as hardness test were carried out. As the result of this study, no influence of ionizing radiation on the mechanical properties (hardness, Young’s modulus, tensile strength) of the tested material was observed.