High-energy he ion bombardment-induced modifications of surface properties of UHMWPE

Abstract

Ultra high-molecular-weight polyethylene (UHMWPE) is the material of choice for the load-bearing surfaces of total joint implants. This is primarily due to its good wear resistance. However, failure is often observed as a result of the UHMWPE brittleness. In order to improve its mechanical properties, UHMWPE was bombarded with 4-MeV He ions to fluence ranging from 1012 to 5 × 1014 ions/cm2. Changes of surface layer composition produced by ion bombardment of UHMWPE samples were studied. Polymer radiolysis due to the ion bombardment leading to hydrogen release was studied by means of nuclear reaction analysis using the1H(15N, αγ)12C reaction. Hydrogen release increasing with the ion fluence was observed and correlated to the ion linear energy transfer. Moreover, important oxidation of bombarded samples was also noticed. These effects resulted in important modifications of the surface properties of bombarded material such as increase of hardness and improved wettability.