Paper PS1-ThM9
Surface Modification of Ultra High Molecular Weight (UHMW) Polyethylene Films Using Atmospheric Pressure Dielectric Barrier Discharges

Thursday, October 23, 2008, 10:40 am, Room 304

In this work, dielectric barrier discharge (DBD) plasmas, operating in nitrogen, air and helium-oxygen at atmospheric pressure, are used to modify the surface properties of ultra high molecular weight polyethylene films. The imposed changes of the hydrophilicity, chemical composition and roughness of the surface appear to have a dependence on the DBD operating parameters such as processing duration and discharge power as well as the nature of the gas being used for the plasma treatment. Contact angle and X-ray photoelectron spectroscopy (XPS) data reveal that in all cases the plasma exposed surfaces exhibit improved wettability that can be attributed to the mild oxidation of polyethylene as confirmed by XPS analysis. Atomic force microscopy (AFM) results show that longer processing duration and higher oxygen concentration are key for increased surface roughness, a factor affecting the adhesion properties of the film. Standard lap-shear evaluations reveal that plasma treatments may lead to significant increases in the bond strength of polymer films and metallic/polymeric substrates and changes in modes (adhesive vs. cohesive) and loci of failure. The plasma treatments increase the mechanical interlocking and frictional energy dissipation effects when bonded to a substrate. Changes in other mechanical properties are also investigated. Most importantly, this uniform modification occurs within a few seconds of exposure, time comparable to continuous on-line industrial processing.