Green and efficient method for preparing all-cellulose composites with NaOH/urea solvent

Piltonen, Petteri; Hildebrandt, Nils C.; Westerlind, Bo; Valkama, Jukka‐Pekka; Tervahartiala, Tero; Illikainen, Mirja

doi:10.1016/j.compscitech.2016.09.022

Cited by 63 publications

(63 citation statements)

References 35 publications

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“…Plasticization partly changes the crystallinity of cellulose fibers from cellulose I to cellulose II, and increases the amorphous cellulose content, thereby changing the fiber and paper properties. 171 Furthermore, plasticization increases the fiberto-fiber bond strength. Plasticization of the surface layers of the cellulose fibers induces higher strain at break, stiffness and tensile strength.…”

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confidence: 99%

The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena

Lindman

Medronho

Alves

et al. 2017

Phys. Chem. Chem. Phys.

189

109

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aCellulose is the most abundant polymer and a very important renewable resource. Since cellulose cannot be shaped by melting, a major route for its use for novel materials, new chemical compounds and renewable energy must go via the solution state. Investigations during several decades have led to the identification of several solvents of notably different character. The mechanisms of dissolution in terms of intermolecular interactions have been discussed from early work but, even on fundamental aspects, conflicting and opposite views appear. In view of this, strategies for developing new solvent systems for various applications have remained obscure. There is for example a strong need for using forest products for higher value materials and for environmental and cost reasons to use water-based solvents. Several new water-based solvents have been developed recently but there is no consensus regarding the underlying mechanisms. Here we wish to address the most important mechanisms described in the literature and confront them with experimental observations. A broadened view is helpful for improving the current picture and thus cellulose derivatives and phenomena such as fiber dissolution, swelling, regeneration, plasticization and dispersion are considered. In addition to the matter of hydrogen bonding versus hydrophobic interactions, the role of ionization as well as some applications of new knowledge gained are highlighted.

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mentioning

confidence: 99%

The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena

Lindman

Medronho

Alves

et al. 2017

Phys. Chem. Chem. Phys.

189

109

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show abstract

“…Several investigators have employed these same compositions as their cold alkaline solvents to prepare their ACCs [3,8,11,12]. Li et al employed a 94% aqueous solution volume of 4.6% LiOH⋅H 2 O/12% urea solution to dissolve 6% cotton/cellulose [7].…”

Section: Resultsmentioning

confidence: 99%

“…Utilizing these techniques, dissolved cellulose could serve as a matrix and be reinforced with undissolved cellulose materials to generate novel all-cellulose composites (ACC) once the alkaline solution was removed [3][4][5][6][7][8][10][11][12]. These novel ACCs are "environmentally friendly" and can be "recycled" since the composite is entirely composed of cellulose [1,3,6,8,[10][11][12]. ACC films (0.25 mm thick) composed of cellulose nanowhiskers and a cellulose matrix has been produced using a cold aqueous alkaline solution (7% NaOH/12% urea at −12 ∘ C) [7,8,11].…”

Section: Introductionmentioning

confidence: 99%

“…The carbohydrate fraction (cellulose and hemicellulose) of lignocellulosic biomass is speculated to be covalently linked to lignin [1,3]. One method used to break down the lignocellulosic bonds is to employ cold alkaline solvents [1][2][3][4][5][6][7][8][9][10][11]. For example, cold sodium hydroxide (7% NaOH) or sodium hydroxide/urea solutions (≈7% NaOH/12% urea solution) cooled to −12 ∘ C is capable of breaking cellulose linkages to synthesis cellulose derivatives [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

“…These novel ACCs are "environmentally friendly" and can be "recycled" since the composite is entirely composed of cellulose [1,3,6,8,[10][11][12]. ACC films (0.25 mm thick) composed of cellulose nanowhiskers and a cellulose matrix has been produced using a cold aqueous alkaline solution (7% NaOH/12% urea at −12 ∘ C) [7,8,11]. Recently, a cold aqueous alkaline solution of LiOH⋅H 2 O (4.6% LiOH⋅H 2 O : 15% urea at −12 ∘ C) was used to generate a nonporous cellulose gel from cotton fibers [7].…”

Section: Introductionmentioning

confidence: 99%

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Lignocellulosic Composites Prepared Utilizing Aqueous Alkaline/Urea Solutions with Cold Temperatures

Tisserat

Liu

Haverhals

2018

International Journal of Polymer Science

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Lignocellulosic composites (LCs) were fabricated by partially dissolving cotton to create a matrix that was reinforced with osage orange wood (OOW) particles and/or blue agave fibers (AF). LCs were composed of 15-35% cotton matrix and 65-85% OWW/AF reinforcement. The matrix was produced by soaking cotton wool in a cold aqueous alkaline/urea solvent and was stirred for 15 minutes at 350 rpm to create a viscous gel. The gel was then reinforced with lignocellulosic components, mixed, and then pressed into a panel mold. LC panels were soaked in water to remove the aqueous solvent and then oven dried to obtain the final LC product. Several factors involved in the preparation of these LCs were examined including reaction temperatures (−5 to −15 ∘ C), matrix concentration (15-35% cotton), aqueous solvent volume (45-105 ml/panel), and the effectiveness of employing various aqueous solvent formulations. The mechanical properties of LCs were determined and reported. Conversion of the cotton into a suitable viscous gel was critical in order to obtain LCs that exhibited high mechanical properties. LCs with the highest mechanical properties were obtained when the cotton wools were subjected to a 4.6% LiOH/15% urea solvent at −12.5 ∘ C using an aqueous solvent volume of 60 ml/panel. Cotton wool subjected to excessive cold alkaline solvents volumes resulted in irreversible cellulose breakdown and a resultant LC that exhibited poor mechanical properties.

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Cellulose Nanocrystals‐Based Composites

Mokhena

John

Mochane

et al. 2019

Soil Microenvironment for Bioremediation and Polymer Production

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Green and efficient method for preparing all-cellulose composites with NaOH/urea solvent

Cited by 63 publications

References 35 publications

The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena

The relevance of structural features of cellulose and its interactions to dissolution, regeneration, gelation and plasticization phenomena

Lignocellulosic Composites Prepared Utilizing Aqueous Alkaline/Urea Solutions with Cold Temperatures

Cellulose Nanocrystals‐Based Composites

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