Holistic Rice Straw Nanocellulose and Hemicelluloses/Lignin Composite Films

Rice straw was dewaxed and optimally separated into cellulose-rich solid and hemicelluloses/lignin (HL)-rich aqueous suspension with two 5 min alkali immersions (4% NaOH, 70 °C). Alkaline cellulose nanofibrils (ACNFs) were derived, at 36.5% yield from the original rice straw, by TEMPO-mediated oxidation and mechanical defibrillation of cellulose-rich portion whereas HL was isolated at 18.1% yield from the aqueous suspension. Aqueous HL solutions containing up to 30% ACNF as well as three other nanocelluloses, i.e., cellulose nanocrystals (CNC), TEMPO oxidized and aqueous counter collision generated CNFs (OCNF and ACCNF) were cast into films to exhibit significantly improved flexibility, transparencies, mechanical and moisture barrier properties. The structure–properties relations of these holistic composite films were analyzed systematically, in particular regarding to the types and loadings of the different nanocelluloses.