Eur. Phys. J. Appl. Phys. 43, 289-294 (2008)
https://doi.org/10.1051/epjap:2008076

Surface treatment of a polypropylene film with a nitrogen DBD at medium pressure

¹ Ghent University, Department of Applied Physics, Research Unit Plasma Technology (RUPT), Jozef Plateaustraat 22, 9000 Ghent, Belgium
² Université des Sciences et Technologies de Lille, Unité de Catalyse et Chimie du Solide, UMR CNRS 8181, bâtiment C3, Cité Scientifique, 59655 Villeneuve d'Ascq, France
³ Ghent University, Department of Organic Chemistry, Biomaterials Research Group, Faculty of Sciences, Krijgslaan 281, S4, 9000 Ghent, Belgium

Corresponding author: rino.morent@ugent.be

Received: 13 November 2007
Revised: 15 January 2008
Accepted: 22 January 2008
Published online: 30 April 2008

Abstract

Surface treatment of polymer films is usually necessary to improve surface wetting and adhesion characteristics. Traditional liquid chemical processes have several disadvantages in contrast to dry finishing processes, like plasma technology. Dielectric barrier discharges at atmospheric pressure are extensively studied for surface treatment, however, almost no research has been done on surface treatment with a dielectric barrier discharge at medium pressure. Therefore, in this paper, a polypropylene (PP) film is plasma-treated with a dielectric barrier discharge (DBD) in nitrogen at medium pressure (5.0 kPa). The surface properties of the plasma-treated samples are examined using contact angle measurements, X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). Results show that the surface wettability is significantly enhanced after plasma treatment. The incorporation of nitrogen on the surface is significant (10 at%), demonstrating the ability of the used DBD set-up to generate nitrogen-containing functional groups on the PP surface. Nevertheless, a considerable amount of oxygen (10 at%) is incorporated onto the PP surface underlining the extreme reactivity of oxygen active species and the difficulty in overcoming the air contamination problem. Moreover, AFM analysis reveals that the nitrogen plasma creates large changes in the surface morphology of the PP film due to the selective etching of the amorphous regions of the polymer film.