Study of Argon and Oxygen Mixtures in Low Temperature Plasma for Improving PLA Film Wettability

Oxygen (O-2) and argon (Ar) plasma give a significant improvement in the wettability of PLA films. This study investigates the effectiveness of plasma activation with a mixture of these two gases. The study includes contact angle measurements with water and diiodomethane and calculation of surface free energy (SFE) together with its polar and dispersion components. In addition, a chemical analysis of the surface, surface roughness, weight loss and the change in tensile strength were examined. As a result of the study, it was found that the use of a mixture of oxygen and argon during the plasma activation of the polylactide film gives better improvement in wettability than the use of pure gases. Moreover, the use of a mixture of these gases in equal proportions turned out to be the most effective, providing the highest value of the SFE and its polar component, as well as the lowest value of the water contact angle. Furthermore, plasma activation with this gas mixture results in reduced surface etching compared to other gas compositions, which manifests itself in lower weight reduction and an insignificant change in tensile strength.