Bionanocomposite films of nanocellulose with chitosan or alginate: Enhanced barrier properties and active packaging potential

Abstract

In this study, two biopolymers—alginate and chitosan—were combined with nanofibrillated cellulose (NFC) at varying concentrations (5–80%) to produce alginate-NFC and chitosan-NFC bionanocomposites. FTIR confirmed the good compatibility between NFC and the biopolymers. Subsequently, the optical, physical, and barrier properties relevant to packaging applications were evaluated. The incorporation of both biomacromolecules resulted in smoother and more transparent bionanocomposites. While a low concentration of alginate (5%) reduced both tensile strength and elongation at break, significant negative effects on these mechanical properties were only observed at higher chitosan loadings (50–80%). Surface hydrophobicity, evaluated by water drop test (WDT) and water contact angle (WCA), was also enhanced, reaching WCA values of 104° and 82° with 70% chitosan and alginate, respectively. Water vapor barrier performance (50% and 90% RH) improved only with chitosan addition, whereas grease barrier properties were enhanced exclusively by alginate. These contrasting effects are attributed to differences in surface free energy: chitosan increased the dispersive component of the bionanocomposites (up to 95%), while alginate introduced a strong polar character (65–82%). The results enabled insight into the interfacial interaction mechanisms among biopolymers in bionanocomposite matrices. Finally, both biopolymers provided oxygen scavenging capacity to bionanocomposites, making them promising candidates for active packaging applications—chitosan by increasing antioxidant activity, and alginate by facilitating the immobilization of an oxidoreductase-type enzyme

The authors would like to thank the consolidated research group AGAUR 2021 SGR 00852. Oriol Cusola and Cristina Valls are Serra Húnter Fellows

9 - Indústria, Innovació i Infraestructura

11 - Ciutats i Comunitats Sostenibles

12 - Producció i Consum Responsables

13 - Acció per al Clima

Postprint (published version)