(714b) Ductility Improvement of Film Products Made of Nano-Fibrillated Saccharification Residues of Wood

The objective of this study was to investigate the effects of polymer incorporation on the tensile properties of films made of nano-fibrillated saccharification residues of wood. In earlier work, we demonstrated that it is technically feasible to utilize these lignin-rich residues for making plastic-like films, but the resulted films are brittle. In this study, we addressed the issue by incorporating a ductile thermoplastic at relatively low mass fractions, in contrast to the conventional approach (low fiber content) with nanofiber-polymer matrix composites. To implement this research, aspen wood flour was first pre-treated with an alkaline solution and then enzymatically saccharified to attain 80% glucose release from glucan. The solid residuals were mechanically fibrillated in aqueous media to fibrous fragments of micron and nanometer size. Some pre-treated wood flour (without saccharification) was also subjected to mechanical fibrillation. Fibrillated fragments from both pre-treated and saccharified biomass were blended at a solid mass ratio of 50:50. An appropriate amount of poly (vinyl alcohol) (PVA) solution was added to the mixture, and the slurry was immediately decanted to form into mats and subsequently dried to films. Results showed that PVA incorporation at 1.2% and 21% mass fraction of the films slightly improved tensile strain at break, but the films remained brittle. Increasing the PVA content to 37% mass fraction increased the strain to three folds, without compromising tensile strength of the films. From 24h-soaking study, incorporation of PVA also has the advantage of maintaining the film integrity in water with negligible weight loss (~1.0%). Other results such as wet strength and moisture adsorption will be discussed in the light of application potential. Overall, we successfully improved ductility while sustaining the tensile strength of nanofiber films. This outcome contrasts with the use plasticizers which usually increase ductility at the expense of strength (in addition to stiffness). By improving ductility of films containing saccharification residues, this study contributes to expanding the application window and value of the film products, thereby advancing the possibility of coproducing sugars and value-added materials from bioconversion of woody biomass.