Incorporation of zinc oxide nanoparticles improved the mechanical, water vapor barrier, UV-light barrier, and antibacterial properties of PLA-based nanocomposite films.

Zinc oxide nanoparticles (ZnO NPs) were synthesized using zinc chloride and NaOH and they were incorporated to prepare PLA/ZnO NPs composite films. The SEM images showed that the ZnO NPs were cubical in shape with size ranged from 50 to 100 nm, and the PLA/ZnO NPs composite films were smooth and compact. The composite films exhibited strong UV-light barrier property with a slight decrease in the transparency. The thickness, tensile strength, and water vapor barrier property of the films increased significantly after incorporation of ZnO NPs. The TS of PLA films increased by 37.5%, but the WVP decreased by 30.5% from 3.11 × 10-11 to 2.16 × 10-11 g m/m2·Pa·s when 0.5 wt% of ZnO NPs was incorporated. The composite films exhibited potent antibacterial activity against food-borne pathogenic bacteria, Escherichia coli and Listeria monocytogenes. The developed films were applied to the packaging of a minced fish paste and showed strong antibacterial function. The prepared composite films could be used as antibacterial and UV-light barrier films for food packaging and biomedical applications.