Crystallinity Reconstruction of Squid-Pen Chitosan into Mechanically Robust and Multifunctional Bionanocomposite Food Packaging Film.

First, we explore the effect of bioacids on the film processing of preprocessed, i.e., deacetylated, chitosan (d-chitosan with molecular weight of 1,000,000 kDa), using monocarboxylic acid (acetic acid), dicarboxylic acid (malic acid), and tricarboxylic acid (citric acid) as model weak acidic solvents to destabilize the hydrogen bonding and transform crystal structures into film. Second, we investigate the chemical and physical toughening effect in the bionanocomposite film composed of cross-linkable multicarboxilic acid, i.e., succinic acid (SA). In doing so, the addition of glycerol as a plasticizer can increase polymer chain mobility, making the biocomposite film more ductile and flexible. The addition of CNC also enhances the tensile strength (41.6%), swelling (43.47%), and oxygen barrier properties (38.81%), as well as significantly improves UV light barrier. The excellent antibacterial properties (99.9% efficiency against S. aureus and K. pneumoniae) of the prepared biocomposite films are found to be independent of the presence of glycerol or CNC. Third, the development of film processability under an industrially relevant process is also demonstrated by doctor blade method. It is found that film processability of the squid-pen's chitosan bionanocomposite can straightforwardly be compatible with and improvable in the presence of poly(vinyl alcohol) employed as a model biodegradable processing aid.