One of the most interesting biologically compatible polymers for producing packaging films is poly(vinyl alcohol) (PVA). PVA is a water-soluble synthetic polymer with excellent film-forming properties. By adding various types of nanofibrillated cellulose (CNF) obtained from wood, we aimed to improve moisture resistance and mechanical properties. The research is based on different types of nanofibrillated cellulose, an extract from the knots of silver fir (Abies alba), and the biologically compatible polymer PVA. Nanofibrillated cellulose (CNF) was prepared in two different ways. Both pretreatments resulted in a negative charge on the CNF surface (repulsion between fibrils), making further mechanical treatment (HPH) less energy-intensive. In the first case, TEMPO CNF was obtained after HPH, and in the second, cellulose nanofibrils with a higher lignin content, LCNF, were obtained. The resulting NFs were used to reinforce the PVA films. Antioxidant compounds were extracted from live and dead knots using the Thermo Dionex ASE 350 system. The extract was mixed with the PVA matrix in various proportions, to which different types of CNF were also added. The developed films were tested for mechanical properties, water contact angle, and FTIR analysis. The results of the tensile test indicate that the required amount of added CNF is relatively small compared to the percentage improvement in mechanical properties. In addition to nanocellulose fibrils, an extract from silver fir was added to the polymer solution to enhance the antioxidant properties of the films.
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