Evaluation of a reel-to-reel atmospheric plasma system for the treatment of polymers

Abstract

Plasma treatments are widely used to enhance the surface energy of polymers prior to bonding or the application of functional coatings. This study investigates the performance of a linear atmospheric pressure plasma source for the reel-to-reel treatment of polymer webs. The continuous argon plasma treatments were carried out on 15 cm diameter polyethylene terephthalate (PET) web substrates using the linear plasma source (Plamax), operating at 13.56 MHz. The study investigated how the processing parameters influenced the effectiveness of the plasma treatment in enhancing both the polymer web's water contact angle (WCA) and surface energy (SE). Based on these measurements the plasma treatment was found to yield a homogeneous level of activation across the 15 cm web, using a treatment speed of 0.9 m/min. The plasma discharge was monitored using both thermal imaging and optical emission spectroscopy (OES). The latter demonstrated how the oxygen species which diffuse into the argon plasma due to air ingress, were directly correlated with the level of polymer activation.