The influence of the film formation process on the properties of nanocellulose-lignin nanoparticle films: Casting versus filtration

In recent decades, there has been growing interest in exploring new applications for lignin, not only to enhance the profitability of emerging lignocellulosic biorefineries, but also to develop new renewable and low-cost biobased products capable of replacing traditional fossil-based materials, such as plastics. In this context, the present work has studied the combination of kraft lignin nanoparticles (LNP) with cellulose nanofibers to develop bioactive films with promising characteristics for food packaging applications, including antioxidant, antibacterial, and UV-shielding abilities. Interestingly, significant differences were observed between films prepared by casting evaporation and those prepared by filtration plus drying in a Rapid-Köthen sheet former, with lower active properties observed in the latter due to lower liberation of lignin in contact with food simulants. Furthermore, water vapor permeability was also improved by the incorporation of LNP in casting films, contrary to filtration films, while mechanical properties remained unchanged or even slightly improved for LNP content up to 5-10 %.