Nanocellulose Filled Bio-Based PVA/Chitosan Nanocomposites: Structure–Property Relationships toward Advanced Food Packaging Films

Biodegradable chitosan/poly(vinyl alcohol) (PVA) composite films were reinforced either with nanocrystalline cellulose (CNC) or nano-lignocellulose (NLC) and evaluated across a polyparametric design of five matrix ratios and three filler levels, for active food packaging applications. ATR-FTIR, DSC, XRD and SEM demonstrated that 1-5% nanocellulose load-ing induced a single relaxation temperature (Tg), homogenized the morphology and en-hanced the crystallinity of blend material, evidencing improved thermodynamic compati-bility. SEM confirmed uniform filler dispersion up to 5% loading in PVA-rich matrices, whereas limited aggregation appeared in chitosan-dominant systems. CO2 barrier property (CO2 permeability coefficients) was diminished by more than two orders of magnitude and fell below 0.01 Barrer in CNC-filled 25-75 and NLC-filled 75-25 blends, while permeability to O₂ and N₂ remained undetectable under identical conditions. Meanwhile, Young’s modulus increased to 3.9 GPa, and tensile strengths of up to 109 MPa were achieved, without affecting the ductility in specific loading values. These data confirm that tailored selection of the filler/matrix combination, rather than elevated nanocellulose content, can simultaneously optimize barrier performance and mechanical integrity. The study there-fore offers a scalable, water-based route for producing optically transparent nanocomposite membranes that satisfy strict modified atmosphere packaging (MAP) applications and advance the transition toward compostable/or even edible high-performance food contact materials.