Comparison of the surface characteristics of polypropylene films treated by Ar and mixed gas (Ar/O2) atmospheric pressure plasma

In an attempt to modify the hydrophobic surface properties of polypropylene (PP) films this study examined the optimum process parameters of atmospheric pressure plasma (APP) using Ar- gas. Under optimized conditions, the effects of a mixed gas (Ar/O-2) plasma treatment on the surface-free energy of a PP film were investigated as a function of the O-2 content. The polar contribution of the surface-free energy of the PP film increased with increasing O-2 content in the gas mixture. However. slightly more oxygen-containing polar functional groups Such as -CO, -C=O, and -COO were introduced on the PP film surface by the Ar gas only rather than by the Ar/O-2 gas mixture. In addition. AFM analysis showed that the Ar plasma treatment of the PP film produced the smoothest surface as a result of the relatively homogeneous etching process. (c) 2005 Elsevier Inc. All rights reserved.