Trade-Offs Between Antioxidant Functionality and Physical Properties of Glycerol-Plasticized Chitosan Nanocomposite Films Containing Different-Sized Lignin Nanoparticles

This study investigated the effects of adding lignin nanoparticles (LNPs) to glycerol-plasticized chitosan nanocomposite films (pCS-LNP). Specifically, different LNP sizes (mean hydrodynamic diameters of about 70, 125 or 170 nm) and loadings (1, 3 or 5% of CS) were studied. The two largest LNP types aggregated mostly in the upper side of the cast films, while the smallest LNP type was found more uniformly throughout the film cross-section. The results showed a trade-off between film properties. Both UV barrier, visible light opacity and antioxidant properties increased with increasing LNP loading, while smaller LNPs resulted in higher stiffness and tensile strength than larger types. The radical scavenging activity of the films correlated with the migration of lignin-derived substances out of the films.