Mechanism of oxygen and argon low pressure plasma etching on polyethylene (UHMWPE)

Different preferential sites for etching are observed for low pressure argon and oxygen plasma on ultra-high molecular weight polyethylene. Atomic force microscopy analysis showed an organized pattern after 1 min of oxygen plasma treatment. Roughness decreases after 3 min and then after 5 min increases again, when surface is completely damaged. A different etching pattern is observed after argon plasma treatment, where nanometric pits are formed with size increasing with treatment time. Infrared spectroscopy shows that, by analyzing the relative intensity of the different peaks, the different etching mechanisms are explained where oxygen plasma reduces coupling between parallel chains in the crystalline short axis direction and argon plasma suppresses hydrogen and induces surface reorientation of functional groups.