Influence of ambient conditions on the ageing behaviour of plasma-treated PET surfaces

Plasma treatment is often used to modify the surface properties of polymer films, since it offers numerous advantages over the conventional surface modification techniques. However, plasma-treated polymer films have a tendency to revert back to the untreated state (ageing process). Therefore, the stability of plasma induced changes on polymer surfaces over a desired period of time is a very important issue. The objective of this study is to examine the effect of storage conditions (relative humidity, temperature and pressure) on the ageing behaviour in air of plasma-treated polyethylene terephthalate (PET) films. Plasma treatment is performed using a dielectric barrier discharge (DBD) operating in air at medium pressure (5.0 kPa). Results show that the ageing process can be suppressed by storing the PET films at low temperature or by decreasing the relative humidity of the surrounding air. In this paper, it is also shown that decreasing pressure has no influence on the ageing process.