Rotary DBD Plasma Reactor for Inline Treatment of Polymeric Substrates

The aim of this paper is to present the effects of DBD non-thermal plasma treatment on the surfaces of polymeric foils used in packaging industry, namely $20\ \mu\mathrm{m}$ thickness PET foil. The treatment was performed in air, at atmospheric pression and humidity, using a rotary DBD discharge. The reactor was design to allow inline treatment of the substrate in roll-to-roll configuration. The plasma was generated using a high voltage and high frequency power supply. Two different voltage values of 8.5 and 7 kV were considered while the frequency was in the range of 16.6 kHz. The effects of the plasma treatment were evaluated by measuring the water contact angle (WCA) using a goniometer and the surface tension using Arcotest test pens. The influence of discharge voltage, treatment time and foil speed were evaluated. The results indicated a decrease of PET surface WCA from over 75 to around 30 degrees after DBD treatment, even for treatment times of 65 ms, while the surface tension is increasing from 36 mN/m to over 60 mN/m.