Barrier packaging solutions from residual biomass: Synergetic properties of CNF and LCNF in films

In this paper, for the first time, it is studied the synergetic properties of two different grades of nanocelluloses with different chemical compositions (cellulose nanofibrils-CNF with less than 1% of lignin and lignocellulose nanofibrils-LCNF with 16% of lignin). CNF and LCNF were mixed in different ratios to obtain bi-component films. Their performance in terms of transparency, bioactivity, thermo-mechanical and gas barrier properties was evaluated and compared with the performance of the neat CNF films. The presence of LCNF in the formulations conferred antioxidant and UV blocking properties to the films, as well as improved mechanical and barrier properties. Specifically, the incorporation of 25% LCNF to the CNF films increased the mechanical properties (94% increase in tensile stress and a 414% increase in strain at break) and decreased the water vapor transmission rate by 16% and the oxygen transmission rate by 53%. This performance improvement was attributed to the coexistence of nanocelluloses with different chemical composition and morphology. LCNF contributed to increment the interfacial adhesion between cellulose nanofibrils due to the presence of lignin and promote the creation of more tortuous paths for gas molecules. These synergetic properties shown by the CNF/LCNF bi-component films demonstrate high potential to be used as gas barrier packaging solutions.