SURFACE CHARACTERIZATION OF ION-IMPLANTED POLYETHYLENE

Polyethylene (PE) film was implanted with 1000-keV Ari ions to a fluen ce of 5 x 10(14) ions/cm(2) under high vacuum conditions (2.5 x 10(-6) torr) and the film surface was investigated by means of microhardness and microwear measurements, and FTIR/ATR, Raman, and XPS techniques. Ion implantation significantly increased the subsurface hardness and a lso significantly improved the microwear resistance of the polymer. Th e implanted surface region of the film was found to consist of two dis tinct layers. One was the outermost carbon layer with a thickness of t he order of 10 nm. In this layer, ca. 75% of carbon atoms were combine d by graphitic sp(2) and diamond-like sp(3) bonds, and the remaining 2 5% had chemical links with oxygen atoms. Spectroscopic data suggested that the sp(2)-bonded carbons segregated in graphite-like clusters con taining imbedded oxygen atoms, interconnected by the sp(3)-bonded carb ons. The other was the subsurface layer resulting from PE oxidation af ter ion-beam treatment. This layer was characterized by high contents of O-H and C=O groups as well as ester and double bonds. The chemical composition of the layer was uniform and did not vary over the layer t hickness of about 1.4 mu m. (C) 1998 John Wiley & Sons, Inc.