A Comparative Study of Poly(propylene) Surface Oxidation in DC Low-Pressure Oxygen and Water Vapor Discharges and in Flowing Afterglow of Water Vapor Discharge

The influence of direct current (DC) discharges in oxygen and water vapor and in a flowing afterglow of water vapor discharge onto the surface of poly(propylene) (PP) films was studied. The surface properties of PP were characterized by Fourier transform infrared by attenuated total reflectance (FTIR/ATR), X-ray photoelectron spectroscopy (XPS), Atomic force microscopy (AFM), and contact angle measurement. The action of oxygen and water vapor plasma was found to be similar in terms of the composition of functional groups formed. Unlike plasma action, the PP surface treatment in water vapor discharge afterglow provided a more uniform composition of oxygen-containing groups and greater depth of the modified layer. The formation of alcohol, carbonyl, and carboxyl groups has been observed. The treatment of PP films led to the increase in surface-free energy, the polymer surface becoming more smooth and homogeneous.