Cellulose in NaOH–water based solvents: a review

Budtova, Tatiana; Navard, Patrick

doi:10.1007/s10570-015-0779-8

Cited by 278 publications

(242 citation statements)

References 263 publications

(371 reference statements)

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“…Cellulose is a crystalline polymer, and due to a stable crystalline state, cellulose is insoluble in common polar solvents, as well as in non-polar and intermediate solvents. In spite of intense work during the last century, only a few types of solvents have been proposed for dissolving cellulose (Liebert 2010;Budtova and Navard 2016). As early as the 1900s, concentrated NaOH(aq) was used to dissolve/disperse cellulose in the viscose process.…”

Section: Introductionmentioning

confidence: 99%

“…As early as the 1900s, concentrated NaOH(aq) was used to dissolve/disperse cellulose in the viscose process. However, NaOH(aq) can only dissolve cellulose within a narrow pH range (approximately 1.5-2.5 M NaOH) and only at lower temperatures (typically below 0 C) (Budtova and Navard 2016;Alves et al 2016). The reasons for such limited conditions are still not understood.…”

Section: Introductionmentioning

confidence: 99%

“…Defining a gelation time, t gel , as the time when G 0 ¼ G 00 , Roy et al found that t gel decreased exponentially with increasing temperature. The reason for this gelation is yet not fully understood (Budtova and Navard 2016).…”

Section: Introductionmentioning

confidence: 99%

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On the dissolution state of cellulose in cold alkali solutions

et al. 2017

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We have characterized the dissolved state of microcrystalline cellulose (MCC) in cold alkali [2.0 M NaOH(aq)] solutions using a combination of small angle X-ray (SAXS) and static light scattering (SLS), 1 H NMR, NMR self-diffusion, and rheology experiments. NMR and SAXS data demonstrate that the cellulose is fully molecularly dissolved. SLS, however, shows the presence of large concentration fluctuations in the solution, consistent with significant attractive cellulose-cellulose interactions. The scattering data are consistent with fractal cellulose aggregates of micrometre size having a mass fractal dimension D $ 1:5. At 25 C the solution structure remains unchanged on the time scale of weeks. However, upon heating the solutions above 35 C additional aggregation occurs on the time scale of minutes. Decreasing or increasing the NaOH concentration away from the ''optimum'' 2 M also leads to additional aggregation. This is seen as an increase of the SAXS intensity at lower q values. Addition of urea (1.8 and 3.6 M, respectively) does not significantly influence the solution structure. With these examples, we will discuss how scattering methods can be used to assess the quality of solvents for cellulose.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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On the dissolution state of cellulose in cold alkali solutions

et al. 2017

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“…Undoubtedly one of the most attractive alternative systems is NaOH(aq), which has been extensively studied since the early 1930s in terms of dissolution conditions (Davidson 1934;Sobue et al 1939), dissolution mechanism (Kamide et al 1992), the structure of the dissolved state (Yamashiki et al 1988;Roy et al 2001) and, more recently, additives capable of enhancing the dissolution (Budtova and Navard 2015). In spite of these efforts, the exact mechanism of cellulose dissolution in NaOH(aq) is not fully understood to this day.…”

Section: Introductionmentioning

confidence: 99%

Chemisorption of air CO2 on cellulose: an overlooked feature of the cellulose/NaOH(aq) dissolution system

2017

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A natural abundance of the air CO 2 in NaOH(aq) at low temperature was investigated in terms of cellulose-CO 2 interactions upon cellulose dissolution in this system. An organic superbase, namely 1,8-diazabicyclo[5.4.0]undec-7-ene, DBU, known for its ability to incorporate CO 2 in carbohydrates, was employed in order to shed light on this previously overlooked feature of NaOH(aq) at low temperature. The chemisorption of CO 2 onto cellulose was investigated using spectroscopic methods in combination with suitable regeneration procedures. ATR-IR and NMR characterisation of regenerated celluloses showed that chemisorption of CO 2 onto cellulose during its dissolution in NaOH(aq) takes place both with and without employment of the CO 2 -capturing superbase. The chemisorption was also observed to be reversible upon addition of water: CO 2 desorbed when water was used as regenerating agent but could be preserved when instead ethanol was used. This finding could be an important parameter to take into consideration when developing processes for dissolution of cellulose based on this system.

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“…Lignocellulosic biomass is composed mainly of cellulose (ß (1-4)-linked chains of glucose molecules), hemicellulose (heteropolymers composed of 5-and 6-carbon sugars such as arabinoxylan, xylan, glucronoxylan, glucomannan, and xyloglucan) and lignin (polymer of three phenylpropanoid units: -hydroxyphenyl, guaiacyl, and syringyl). 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].…”

Section: Introductionmentioning

confidence: 99%

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 in NaOH–water based solvents: a review

Cited by 278 publications

References 263 publications

On the dissolution state of cellulose in cold alkali solutions

On the dissolution state of cellulose in cold alkali solutions

Chemisorption of air CO2 on cellulose: an overlooked feature of the cellulose/NaOH(aq) dissolution system

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

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