Insight into the effect of different nanocellulose types on protein-based bionanocomposite film properties

Abstract

This paper investigates the effect of five different types of nanocellulose on the properties of protein-based bionanocomposite films (PBBFs) and the mechanism of action. The results show that TEMPO-oxidized nanocellulose (TNC) PBBFs have the smoothest surface structure. This is because some hydroxyl groups in TNC are converted to carboxyl groups, increasing hydrogen bonding and cross-linking with proteins. Bacterial nanocellulose (BNC) PBBFs have the highest crystallinity. Filamentous BNC can form an interlocking network with protein, promoting effective stress transfer in the PBBFs with maximum tensile strength. The PBBFs of lignin nanocellulose (LNC) have superior elasticity due to the presence of lignin, which gives them the greatest creep properties. The PBBFs of cellulose nanocrystals (CNCs) have the largest water contact angle. This is because the small particle size of CNC can be uniformly distributed in the protein matrix. The different types of nanocellulose differ in their microscopic morphology and the number of hydroxyl groups and hydrogen bonding sites on their surfaces. Therefore, there are differences in the spatial distribution and the degree of intermolecular cross-linking of different types of nanocellulose in the protein matrix. This is the main reason for the differences in the material properties of PBBFs.