Enhancing the value of lignocellulosic biomasses through the production of bionanocomposites

The aim of this work was to optimize a methodology to extract cellulose and to produce NC, from different lignocellulosic biomasses (sorghum, Sorghum bicolor (L.) Moench and sunn hemp, Crotalaria juncea L.). In addition, the NC produced was tested as a reinforcing agent in chitosan (Ch) films, to understand its effects on the properties of this biopolymer. The nanoparticles obtained from sorghum and sunn hemp were incorporated in Ch films at a rate of 2.5% w/w of chitosan, and the resultant bionanocomposites (Sorghum NC films and sunn hemp NC films) were fully characterized in terms of their morphology, mechanical and optical properties, permeability (water vapor), water wettability, and FT-IR spectra analysis. Chitosan films reinforced with commercial nanocellulose at the same rate were tested for comparison, as well as pristine chitosan (control). Bionanocomposites made from sorghum and sunn hemp NC were slightly more saturated and opaque than the pristine chitosan films, in particular outer sorghum NC films. Sunn hemp NC films also showed a slightly higher thickness than sorghum NC films and pristine chitosan films. Further, the results confirmed that sorghum NC improved the strength and stiffness of the chitosan biopolymer and that sunn hemp NC improved the plasticity of the chitosan polymer. Hence, results indicate that those lignocellulosic crops may afford a source of NC for the production of bionanocomposites. Considering the application of those bionanocomposites by the food packaging industry, sorghum NC - chitosan films showed more promising results than sunn hemp NC-chitosan films.