Corona-Treated LDPE Bilayer Films Coated with Chitosan/Glycerol and Carvacrol@Zeolite Nanohybrid for High-Oxygen-Barrier Active Packaging

This study developed high-oxygen-barrier active bilayer packaging films by combining corona-treated low-density polyethylene (LDPE) with chitosan/glycerol (CS/Gl) and carvacrol@natural zeolite (CV@NZ) nanohybrid layers using industrially scalable processes. LDPE film was surface-activated via ambient-pressure corona treatment (0.75 s/cm2 at 45 kV, 30 W) and assembled with solution-cast CS/Gl or CS/Gl/CV@NZ monolayers via hot-pressing (110 °C, 1 min). Corona treatment enabled robust interfacial adhesion, evidenced by statistical equivalence between monolayer and bilayer mechanical properties. Incorporation of 10 wt.% CV@NZ nanohybrid increased elastic modulus by 60% (to ≈2970 MPa) and tensile strength by 30% (to ≈50 MPa). The LDPE-CS/Gl film achieved a 64-fold reduction in oxygen permeability; CV@NZ incorporation maintained excellent barrier performance (22-fold reduction). Antioxidant potency increased 16-fold upon CV@NZ incorporation. The LDPE-CS/Gl/CV@NZ film demonstrated exceptional antibacterial activity (5.08–5.30 log reductions; >99.999% kill) against both Listeria monocytogenes and Escherichia coli—substantially exceeding additive effects—confirming synergistic action between chitosan and carvacrol. In fresh minced pork preservation (8 days, 4 °C), the active film achieved a 1.73 log reduction in Total Viable Count (98.2% inhibition) and extended microbiological shelf life from 6 to beyond 8 days (33% increase). The bilayer configuration utilizes only 40% of the total thickness as biopolymer, aligning with circular economy principles. Unlike conventional high-barrier films (e.g., PA/PE) which require complex compatibilization for recycling, the water-soluble chitosan layer in this bilayer design can be readily separated from the LDPE backbone, enabling recovery of a pure polymer stream. This work demonstrates a feasible pathway for developing next-generation active packaging that combines a high oxygen barrier, potent antioxidant activity, and exceptional antimicrobial efficacy through industrially scalable manufacturing.