Preparation of Modified Nano-ZnO Reinforced Linear Low-Density Polyethylene/Cyclic Olefin Copolymer Nanocomposite Films for Maintaining Strawberry Freshness

To develop active packaging for extending the shelf life of perishable fruits like strawberries, this study fabricated a multifunctional nanocomposite film. The film was based on a linear low-density polyethylene/cyclic olefin copolymer (LLDPE/COC) blend to provide a high barrier matrix, into which zinc oxide nanoparticles (ZnO NPs) modified with the silane coupling agent KH-570 were incorporated to impart antibacterial functionality. The modified ZnO NPs showed improved dispersion within the polymer matrix as confirmed by SEM analysis. The resulting blown films exhibited enhanced comprehensive properties. Notably, the optimal film (LLDPE/COC/ZnO-1) achieved a tensile strength of 34.75 MPa and an elongation at break of 1189.03%. Compared to the pristine blend film, the nanocomposite film demonstrated a reduction of 7.35% in water vapor transmission rate (WVTR) and 2.5% in oxygen transmission rate (OTR). Critically, the film demonstrated strong antibacterial activity, showing inhibition rates of approximately 90.69% against Escherichia coli and 92.16% against Staphylococcus aureus . In practical strawberry preservation tests, the nanocomposite packaging effectively slowed down decay, weight loss, and softening, extending the shelf life by 3 days compared to conventional polyethylene packaging. This work presents a promising strategy for designing high-performance, multifunctional food packaging materials. Graphical KH-570 modified nano-ZnO was incorporated into an LLDPE/COC blend via blow molding. The optimal nanocomposite film (1 wt% ZnO) exhibited enhanced mechanical strength, barrier properties, UV-shielding, and antibacterial activity, successfully extending strawberry shelf life by 3 days. This work provides a promising strategy for multifunctional active food packaging.