Chitin Nanofiber-Reinforced Chitosan Films: Enhancing Mechanical and Barrier Properties for Sustainable Packaging.

The consumption of single-use plastic packaging has tremendously increased in the past decade, resulting in a substantial accumulation of plastic waste in the environment. Our focus is to improve the properties of biodegradable packaging films to match those of petroleum-based films while retaining their biodegradability. In this study, we utilized shrimp shells from seafood industries, a main chitin source, to prepare chitin nanofibers (ChNFs) through the combined deacetylation treatment and mechanical disintegration. The ChNFs were subsequently incorporated into chitosan films by a solvent casting approach, and their properties were investigated. The incorporation of ChNFs led to a remarkable enhancement in the mechanical properties of the chitosan films. The addition of 5 wt% ChNFs resulted in a significant improvement of approximately 95% and 80% in tensile strength and Young’s modulus, reaching 61.8 MPa and 2.5 GPa, respectively, compared to neat chitosan films.  Additionally, the presence of ChNFs hindered the water absorption of the chitosan films. With the introduction of 5 wt% ChNFs, a significant decrease in water absorption, from 889% to 183%, was observed. This improvement can be attributed to the better interaction between chitosan and ChNFs. Furthermorer, the well-dispersed ChNFs within the composite films created a torture pathway, resulting in improved barrier properties, including water vapor permeability and oxygen transmission rate. To evaluate the practical application of these materials, we applied them to fresh bananas and found that they significantly extend their shelf life by over 6 days compared to uncoated bananas. Overall, these findings demonstrate the potential of ChNF-reinforced chitosan films as sustainable alternatives to petroleum-based packaging materials.