Fabrication of all-cellulose nanocomposites from corn stalk.

Abstract

There is a need to help farmers and industries develop value-added composite and nanocomposite materials from agricultural residuals. Cellulose nanofibers (CNFs) were made using a TEMPO oxidation method and celluloses were prepared by acid-base method and extracting method, which were all from corn stalk, an agricultural residual. The prepared celluloses were dissolved separately in dimethylacetamide/LiCl solvent and CNFs were added at 0.0%, 0.5%, 1.5% and 3.0% to form all-cellulose nanocomposites, and then cast into films. Morphology, structure and properties of the nanocomposite films were characterized using atomic force microscopy, field emission scanning electron microscopy, thermogravimetric analysis, X-ray diffraction and mechanical testing. The all-cellulose nanocomposite films with different cellulose matrices exhibited good optical transparency and layer structure. The all-cellulose nanocomposite films with cellulose prepared by the extracting method (Composite E) exhibited a higher crystallinity, better thermal stability and higher mechanical strength compared to the all-cellulose nanocomposite films with cellulose prepared by the acid-base method (Composite A). The crystal structure of the all-cellulose nanocomposite films indicated the coexistence of cellulose I and cellulose II. However, in contrast to Composite A, the diffraction intensity of cellulose I in Composite E was higher than that of cellulose II. This was another reason that the mechanical properties of Composite E were superior to those of Composite A. In addition, the mechanical properties of the all-cellulose nanocomposite films were significantly different when the addition of CNFs reached 3.0% by weight, as indicated by a multiple-range comparison. © 2020 Society of Chemical Industry.