Improvement of PET surface modification using an atmospheric pressure plasma jet with different shielding gases

This work demonstrates the influence of shielding gases on the performance of an atmospheric pressure plasma jet (APPJ) and its efficiency in polyethylene terephthalate (PET) surface treatment. The impact of the shielding gas type (argon, nitrogen) and its flow rate on the spatial distribution of the reactive plasma species is determined by applying optical emission spectroscopy (OES) while surface analysis techniques reveal the influence of the plasma footprint on the polymeric surface under the same conditions. The findings indicate that the optical emission intensity of the reactive species is highly influenced by the shielding gas injection. Moreover, adding argon to the ambient atmosphere of the plasma jet during the treatment improves the PET degree of wettability and the size of the modified area. This outcome is supported by an increase in the amount of incorporated oxygen through increments in C-O and O-C=0 groups. Compared to argon, nitrogen shielding gas decreases the area of the plasma impact and acts as a barrier for activating the surface. These results thus reveal the potency of shielding gases on controlling the APPJ ambient conditions and its surface modification effectiveness