Argon Cold Plasma Modification of Polyethylene Films to Tailor Surface and Barrier Properties

Polyethylene (PE) films are widely used in packaging but require surface modification to improve interfacial adhesion with coatings or laminates that enhance their inherently limited barrier properties. In this study, low-density (LDPE) and high-density polyethylene (HDPE) films are treated with argon (Ar) cold atmospheric plasma (CAP) using a jet-type device, and their properties are characterized prior to and post processing. While plasma exposure enhances wettability by halving the water contact angle (WCA) and increasing surface free energy (SFE), it compromises the film surface structure, increasing water vapor and oxygen permeability by up to 60% and 45%, respectively. Aging tests reveal partial recovery of hydrophobicity, though WCAs stabilize below the untreated values. FTIR spectra indicate the formation of polar groups (hydroxyl and carbonyl) after 10–30 min of treatment, accompanied by increased crystallinity. SEM shows pronounced surface etching and morphological alterations, consistent with roughness analysis, which displays a sharp rise after 10 min followed by a slight decrease at 30 min. Antimicrobial capacity remains limited, while long-term degradation results in minimal weight loss (WL), despite sustaining low WCAs. Overall, although CAP treatment impairs the film intrinsic structure, it significantly improves surface chemistry and topography for interfacial bonding, thus optimizing multilayer packaging applications.