Holistic Rice Straw Nanocellulose and Hemicelluloses/Lignin Composite Films

Abstract

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.

Swelling behavior and chemical stability of chitosan/nanocellulose biocomposites

“…). Similar to the reports of , the hydrogen bonds led to the formation of interconnected network between the hydroxyl groups of nanocellulose and Cs porous wall. Thus, it tightened the porous structure of the Cs .…”

Synthesis of a Stable Solid Acid Catalyst from Chloromethyl Polystyrene through a Simple Sulfonation for Pretreatment of Lignocellulose in Aqueous Solution

“…A longer sulfonation time might result in the desulfonation reaction [26] . Meanwhile, the yield of sugars (xylose and arabinose) showed a similar trend as the total acid amount of the catalyst during the reaction temperature from 100 to 140 °C, indicating that high loading of −SO 3 H was beneficial to the hydrolysis of lignocellulose [27] . When the reaction temperature was further increased, both the yields of xylose and xylan were decreased due to the degradation of sugars [28] …”

The Food–Materials Nexus: Next Generation Bioplastics and Advanced Materials from Agri‐Food Residues

“…FLW may be added with non‐film forming components (such as glycerol [ 484 ] or sorbitol [ 140 ] as plasticizers and CaCl 2 as crosslinker to pectin [ 135 ] ), which may further enhance the physical properties of the final material. Other nonfilm forming components may incorporate active properties, such as tea polyphenols, as has been also exemplified by the antioxidant and antibacterial properties of pomelo peel flour/alginate films.…”

“…[ 474 ] Unfortunately, since the starting materials were not the same in these studies, any comparison of the effect of treatment on the film properties would only be but speculative; Dewaxing and fractionation: Although a bulk FLW was not actually used, rice straw was explored as whole precursor following an alkaline treatment for dewaxing. [ 140 ] Thereby, a cellulose‐rich solid phase and a hemicellulose/lignin‐rich aqueous solution were separated, and the latter was used as a film matrix, while the former was used as a reinforcement (with sorbitol as plasticizer). The addition of the cellulose‐rich phase at 30 wt% on the hemicellulose/lignin matrix increased both tensile strength (from 6.4 to 23.4 MPa) and modulus (from 0.17 to 0.70 GPa), while the elongation was kept at ≈11–12%.…”

“…[487] The formation of related composite materials is especially appealing since the global average price of wheat bran is much lower than that of cassava starch (2020 prices of US$ 0.13-0.20 kg −1 and 0.26-0.42 kg −1 , respectively). [488] FLW may be added with non-film forming components (such as glycerol [484] or sorbitol [140] as plasticizers and CaCl 2 as crosslinker to pectin [135] ), which may further enhance the physical properties of the final material. Other nonfilm forming components may incorporate active properties, such as tea poly phenols, as has been also exemplified by the antioxidant and antibacterial properties of pomelo peel flour/alginate films.…”