Analysis of polymer surface treated by dielectric barrier discharge

We investigate polymer surfaces after exposing them to dielectric barrier discharges with different flowing gases (He, CF4) in air. The relationship between the gas characteristics and the surface properties of polypropylene (PP) is determined by contact angle measurement, optical emission spectroscopy and x-ray photoelectron spectroscopy. Experimental results reveal that there is a definite relationship between the surface energy and the surface chemical composition of PP and also indicate that the hydrophilicity of PP in an atmospheric pressure (AP) discharge is more dependent on ionic bombardment than on the atomic oxygen composition at the surface and its hydrophobicity depends on the fluorine composition at the PP surface. In addition, it turns out that in a CF4 discharge at AP, the CF3 molecular band exhibits a continuum band at the orange line in the visible range.