Structures of cellulose in solution

Schulz, Liane; Seger, Bernd; Burchard, Walther

doi:10.1002/1521-3935(20001001)201:15<2008::aid-macp2008>3.3.co;2-8

Cited by 20 publications

(42 citation statements)

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“…In the case of cellulose chains in Cd-tren, the contraction is lower due to the higher chain stiffness caused by the extensive hydrogen bonds network occurring within and between cellulose chains. As demonstrated by Saalwchter et al (2000) and Schulz et al (2000), molecularly dissolved celluloses behave as semi flexible polymer chains. Consequently, the calculated contraction ratios are 4.6 to 5.1 times lower for bacterial celluloses and cotton linters and 5.4 to 5.9 times lower for wood pulps as compared to flexible polymer chains.…”

Section: Contraction In Native and Regenerated Cellulose Fibersmentioning

confidence: 94%

“…In the case of a flexible carbon polymer chain, hh 2 i = 2 9 DPn 9 l 2 giving L E =L C ¼ DPn= ffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi ffi 2 Â DPn p : In the case of molecularly dispersed cellulose chains, the contraction can be estimated from the radius of gyration Rg and molar mass Mw data measured in the solvent Cd-tren by Saalwchter et al (2000) and Schulz et al (2000). The contraction of cellulose chains from various sources (bacterial celluloses, cotton linters and wood pulps) in Cd-tren is then calculated by using Eq.…”

Section: Contraction In Native and Regenerated Cellulose Fibersmentioning

confidence: 99%

“…8 with the following parameters: DPn = (Mw/162 g mol -1 )/(Mw/Mn) considering a ratio Mw/Mn & 2 as assumed by Saalwchter et al (2000); l & 5.15 Å (length of one anhydroglucose unit in the cellulose crystal lattice); hh 2 i & 6 9 Fig. 10 Contraction ratio vs DPn calculated for a flexible polymer chain and for cellulose chains from different sources (bacterial celluloses, cotton linters, wood pulps) molecularly dispersed in Cd-tren (Rg and Mw data taken from Saalwchter et al 2000;Schulz et al 2000) as compared to the contraction measured for regenerated fibers, bleached cotton hairs and VHV wood pulp fibers Rg 2 corresponds to the average end-to-end distance of cellulose chains in the contracted state. As can be seen on Fig.…”

Section: Contraction In Native and Regenerated Cellulose Fibersmentioning

confidence: 99%

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Rotation and contraction of native and regenerated cellulose fibers upon swelling and dissolution: the role of morphological and stress unbalances

2010

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The authors are grateful to the publisher, Springer, for letting the manuscript being archived in this Open Access repository. The final publication is available at http://www.springerlink.comInternational audienceUpon swelling and dissolution, native cellulose fibers such as cotton hairs or wood fibers are rotating and contracting. Regenerated cellulose fibers are only contracting, not rotating. Cotton hairs show two rotation mechanisms, a well known untwisting, not seen in wood fibers, due to the unwinding of the twists initially induced by the desiccation that occurs at the end of the growth, and a "microscopic rotation" that can also be slightly observed in wood fibers. In addition to these rotation mechanisms, cotton hairs and wood fibers show a rolling up of their primary wall that is due to the higher elongation of the external layers as compared to the internal layers arising during the elongation phase of the cell. Contraction originates from the fact that the cellulose chains are in an extended conformational state due to the spinning process for the regenerated fibers and to the bio-deposition process for native fibers. The contraction is related to the relaxation of the mean conformation of cellulose chains from an extended state to a more condensed state. Physical as well as mechanical modeling will support the experimental observations

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Section: Contraction In Native and Regenerated Cellulose Fibersmentioning

confidence: 94%

Section: Contraction In Native and Regenerated Cellulose Fibersmentioning

confidence: 99%

Section: Contraction In Native and Regenerated Cellulose Fibersmentioning

confidence: 99%

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Rotation and contraction of native and regenerated cellulose fibers upon swelling and dissolution: the role of morphological and stress unbalances

2010

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“…[13] In this paper, the structure of cellulose in LiCl/DMAc solution and the gels prepared from the solution are investigated by SAXS measurements. Furthermore, on the basis of the results of the SAXS measurements, the relation between the structure of cellulose in dissolved and gelled states is discussed.…”

Section: Introductionmentioning

confidence: 99%

Investigation of the Structure of Cellulose in LiCl/DMAc Solution and Its Gelation Behavior by Small‐Angle X‐Ray Scattering Measurements

Ishii¹,

Tatsumi²,

Matsumoto³

et al. 2006

Macromolecular Bioscience

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Cellulose gels were prepared from cellulose in lithium chloride/N,N-dimethylacetamide (LiCl/DMAc) solution. When the cellulose concentration in the solution is above the one at which cellulose molecules overlap, cellulose gels were formed. While the gel prepared by the addition of water was turbid, the one prepared by the ion exchange was colorless, transparent, and optically anisotropic. In order to explain this gelation behavior of cellulose, small-angle X-ray scattering (SAXS) measurements of the cellulose solutions and the gels were performed. The SAXS profiles of the cellulose solutions and the gels suggested that the large-scale fluctuation of the molecular chain density in the solution can be the origin of the molecular aggregates formed in the gel. Furthermore, the differences in the structure of the gels at the macroscopic and the molecular level were discussed in terms of the phase separation and the molecular association.

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“…Even in very dilute solution, cellulose derivatives form aggregates. It was suggested that these aggregates were formed during the processing of cellulose derivatives and they cannot form the real molecular dispersion in common solvents [27]. The R h distribution of the HEC-g-PCL copolymers is similar with that of HEC except that the fraction of chains of the HEC-g-PCL is much lower than that of aggregates of HEC-g-PCL.…”

Section: Resultsmentioning

confidence: 97%

Synthesis and solution behavior of poly(ɛ-caprolactone) grafted hydroxyethyl cellulose copolymers

Jiang

Wang

Sun

et al. 2011

International Journal of Biological Macromolecules

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Structures of cellulose in solution

Cited by 20 publications

References 0 publications

Rotation and contraction of native and regenerated cellulose fibers upon swelling and dissolution: the role of morphological and stress unbalances

Rotation and contraction of native and regenerated cellulose fibers upon swelling and dissolution: the role of morphological and stress unbalances

Investigation of the Structure of Cellulose in LiCl/DMAc Solution and Its Gelation Behavior by Small‐Angle X‐Ray Scattering Measurements

Synthesis and solution behavior of poly(ɛ-caprolactone) grafted hydroxyethyl cellulose copolymers

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