Self-sustained Films of Cellulose/Graphite Composites: Mechanical and Water Vapor Barrier Properties

Cellulosic materials have several applications, from rheological modifiers to structural reinforcement and packaging components. Using cellulosic materials may also contribute to environmental sustainability because it can be sourced from agricultural byproducts. In this work, self-sustained composite films were produced by the casting of TEMPO-oxidized cellulose nanofibers/graphite composite dispersions. Oscillatory rheology and tensile strength tests showed that the presence of graphite did not significantly contribute to the enhancement of neither the rheological nor mechanical properties of the dispersions and films. Morphological analysis showed that particle segregation and setting occurred during film casting, resulting in particle concentration gradient along the thickness of the film. These results could indicate the low exfoliation efficiency of the microfluidization process and, therefore, justify why the graphite did not act as a reinforcement of the cellulose matrix. However, the graphite particles contributed to a higher barrier to water vapor permeation of the cellulosic films.

Keywords:
Nanocellulose; Graphite; Mechanical properties; Rheology; WVTR