Modulating the Properties of Hybrid Nanocellulose\nFilms

The\nenvironmental concerns about petroleum-based polymers drive\nthe search for sustainable alternatives. This paper investigates sustainable\ncellulose nanocrystal (CNC) films for packaging applications. CNC\nfilms are transparent and provide an excellent barrier against oxygen\nwith moderate performance against water vapor. However, they are brittle\nand challenging to handle. Incorporating cellulose nanofibrils (CNFs)\nimproves the mechanical properties and handling of the films, enabling\nthe formation of thinner, more manageable films, although transparency\ndecreases. Water vapor permeability remains almost constant, and while\noxygen permeability increases, it is still significantly lower than\nthat of most petroleum-derived polymers. The optimal balance of properties\nwas achieved with 25% CNF addition. Structural investigation using\nmicro-CT, scanning electron microscopy, and pycnometry revealed that\nthis optimized composite structure is dense, with less than 0.4% internal\nporosity, consistent with a structure where CNCs pack around the CNFs,\nfilling the spaces between them.