Kinetics of Cellulose Regeneration from Cellulose−NaOH−Water Gels and Comparison with Cellulose−<i>N</i>-Methylmorpholine-<i>N</i>-Oxide−Water Solutions

Gavillon, Roxane; Budtova, Tatiana

doi:10.1021/bm060376q

Cited by 84 publications

(65 citation statements)

References 35 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This indicates that the incorporation of CO 2 into cellulose under the conditions studied is reversible and not PRC pre-treated regenerated cellulose (ethanol) favoured when the alkalinity of the system is decreased by the extensive addition of water, which is a behaviour (reported as hydrolysability) expected of alkyl carbonates when brought into aqueous conditions (Franchimont 1910). Regeneration with ethanol, on the other hand, can be assumed to facilitate a fast aggregation of cellulose chains, as it has been shown that dissolved cellulose contracts strongly in alcohol when compared to water (Gavillon and Budtova 2007). This strong contraction could then be the reason for ethanol being able to preserve the chemisorbed CO 2 i.e.…”

Section: Chemical Structures Of Dissolved and Regenerated Cellulosementioning

confidence: 99%

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

2017

View full text Add to dashboard Cite

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.

show abstract

Section: Chemical Structures Of Dissolved and Regenerated Cellulosementioning

confidence: 99%

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

2017

View full text Add to dashboard Cite

show abstract

“…The understanding of the mechanisms governing regeneration kinetics opens the ways in controlling final cellulose morphology. That is why we started to study the regeneration kinetics of cellulose from cellulose-8% NaOH-water gelled solutions (Gavillon and Budtova 2007). It was shown that regeneration in pure water is diffusion-controlled (Fick approach); NaOH diffusion coefficients were determined as a function of cellulose concentration and bath temperature.…”

Section: Introductionmentioning

confidence: 99%

Influence of processing parameters on regeneration kinetics and morphology of porous cellulose from cellulose–NaOH–water solutions

Sescousse

Budtova

2009

Cellulose

Self Cite

View full text Add to dashboard Cite

The kinetics of cellulose regeneration in acetic acid bath from cellulose-8% NaOH-water solutions and gels is studied as a function of gelation conditions, acid concentration and bath temperature. The diffusion coefficient of NaOH from cellulose solution or gel into regenerating bath was calculated. It does not depend either on gelation mode or on acid concentration. On the contrary, cellulose regeneration from non-gelled solutions is slower than from a gel. The increase in bath temperature induces diffusion coefficient increase obeying Arrhenius law. Scanning electron microscopy images of regenerated swollenin-water freeze-dried cellulose and of the same samples dried in supercritical CO 2 show highly porous morphology.

show abstract

“…As expected, the higher the bath temperature, the quicker the NaOH/thiourea/urea/H 2 O released from cellulose samples, and thus the quicker cellulose regeneration. The same occurred for the regeneration of 3% Solucell/NMMO solutions in water baths of different temperatures [9]. Tab.…”

Section: The Effect Of Cellulose Concentration On the Coagulation Promentioning

confidence: 73%

“…On the other hand, too high coagulation concentration could be not only capable of facilitating decomposition of cellulose but also mainly responsible for an increase of the pore size of the fibers, so 1.5 mol/l H 2 SO 4 was found to be the most effective coagulant in our experiments. When cellulose was dissolved in NaOH/H 2 O solution, the results from the literature indicated a different case, cellulose/NaOH/H 2 O gels were contracting more than twice in methanol baths [9]. In most of the cases, the fastest contraction occurs during the first 10-20 seconds after sample immersion into the regenerating bath; during the following 30-40 seconds the sample slowly approaches its equilibrium size.…”

Section: The Effect Of Coagulation Concentration and Time On Boundarymentioning

confidence: 99%

See 1 more Smart Citation

Coagulation studies of cellulose/NaOH/thiourea/urea/H2O fiber spinning system

Zhang

et al. 2009

E-Polymers

View full text Add to dashboard Cite

Abstract:The coagulation properties of cellulose from cellulose//NaOH/thiourea/ urea/H 2 O solutions were investigated with the goal of determining the optimal coagulation conditions for the spinning of cellulose fibers. The present study was concentrated on the effect of the coagulation variables upon the coagulation process. It was observed that at the start of the process, the thickness of the solidified layer ε was proportional to the square root of time. Model experiments were performed on gelled solutions of cellulose/NaOH/thiourea/urea/H 2 O in a coagulation bath to determine the coagulation rate, t /  , and mass transfer rate difference between the solvent and the coagulant, k  . The influence of coagulant compositions, coagulation time and temperature, and cellulose concentrations on coagulation rate and mass transfer rate difference performed on cellulose samples had been demonstrated by microscopic observations, which was important for understanding and controlling the process of cellulose shaping from NaOH/thiourea/urea/H 2 O solutions. The data were analyzed by means of the diffusion model based on Fick's law, thereby depicting the mechanism of the coagulation process, which could be described as a two-phase separation, namely a cellulose-rich phase in the coagulated layer and a cellulose-poor phase in uncoagulated layer.

show abstract

Kinetics of Cellulose Regeneration from Cellulose−NaOH−Water Gels and Comparison with Cellulose−N-Methylmorpholine-N-Oxide−Water Solutions

Cited by 84 publications

References 35 publications

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

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

Influence of processing parameters on regeneration kinetics and morphology of porous cellulose from cellulose–NaOH–water solutions

Coagulation studies of cellulose/NaOH/thiourea/urea/H2O fiber spinning system

Contact Info

Product

Resources

About