Viscosity of aqueous solutions of polysaccharides and their carboxylate derivatives

Nomura, Hiroyasu; Koda, Shinobu; Hattori, Futoshi

doi:10.1002/app.1990.070411133

Cited by 13 publications

(7 citation statements)

References 14 publications

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“…The hydrodynamic properties of aqueous dextran solutions were investigated. At a high concentration of 30 wt %, D50, whose M w was 5.223 × 10 5 , behaved as a pseudoplastic fluid, and this conflicted with the findings by other scientists,10–12 whereas the rest of the experimental results from rheological tests with a low M w value or a low concentration agreed very well with others' results; that is, the aqueous solutions expressed Newtonian properties. In thixotropic property tests, most dextran solutions did not form a thixotropic loop, except for the 30 wt % solution of D50.…”

Section: Discussioncontrasting

confidence: 63%

“…Carrasco et al10 found that all solutions of dextrans with molecular weights ranging from 71,500 to 531,000 and with concentrations up to 30 wt % behaved as Newtonian fluids. Nomura et al11 also found that the solution viscosity of dextrans with molecular weights ranging from 10 4 to 2 × 10 6 and concentrations ranging from 0.5 to 30 wt % to be independent of the shear stress. Tirtaatmaja et al12 also confirmed this point of view by employing dextrans with M w values ranging from 40,000 to 2,000,000 and with concentrations up to 30 wt %.…”

Section: Introductionmentioning

confidence: 96%

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Hydrodynamic properties of aqueous dextran solutions

Xue-lin¹,

Li²,

Zhang³

et al. 2008

J of Applied Polymer Sci

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The hydrodynamic performance of aqueous dextran solutions, including the rheological and thixotropic properties, were investigated. Three kinds of dextrans with different molecular weights were employed to examine the effects of the molecular weight, concentration, temperature, and so forth on the hydrodynamic properties of aqueous dextran solutions. The results showed that an aqueous solution of a dextran with a high molecular weight of 5.223 Â 10 5 at a high concentration of 30 wt % had pseudoplastic properties, in contrast to the conclusions of other researchers finding that aqueous dextran solutions were Newtonian liquids. The viscosity of the aqueous dextran solutions decreased with temperature, and the activation energy was calculated to be 16,849.2 J/mol with a 10 wt % dextran (weight-average molecular weight ¼ 5.223 Â 10 5 ) solution. V

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Section: Discussioncontrasting

confidence: 63%

Section: Introductionmentioning

confidence: 96%

Hydrodynamic properties of aqueous dextran solutions

Xue-lin¹,

Li²,

Zhang³

et al. 2008

J of Applied Polymer Sci

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“…It is known that the molecular weight would increase due to the number of -OCH 2 COONa groups per glucose unit that also increase the hydrodynamic volume of CMSC. This was shown in another study done by Nomura et al [62] regarding about viscosity of CMC and carboxymethylation of dextran [63]. In Table 4, the solubility of CMSC is high (95% dissolved) is attributable to the carboxylate group appended to the cellulose backbone [64].…”

Section: Moisture Contentmentioning

confidence: 52%

Optimizing Extraction of Cellulose and Synthesizing Pharmaceutical Grade Carboxymethyl Sago Cellulose from Malaysian Sago Pulp

et al. 2016

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Abstract:Sago biomass is an agro-industrial waste produced in large quantities, mainly in the Asia-Pacific region and in particular South-East Asia. This work focuses on using sago biomass to obtain cellulose as the raw material, through chemical processing using acid hydrolysis, alkaline extraction, chlorination and bleaching, finally converting the material to pharmaceutical grade carboxymethyl sago cellulose (CMSC) by carboxymethylation. The cellulose was evaluated using Thermogravimetric Analysis (TGA), Infrared Spectroscopy (FTIR), X-Ray Diffraction (XRD), Differential Scanning Calorimetry (DSC) and Field Emission Scanning Electronic Microscopy (FESEM). The extracted cellulose was analyzed for cellulose composition, and subsequently modified to CMSC with a degree of substitution (DS) 0.6 by typical carboxymethylation reactions. X-ray diffraction analysis indicated that the crystallinity of the sago cellulose was reduced after carboxymethylation. FTIR and NMR studies indicate that the hydroxyl groups of the cellulose fibers were etherified through carboxymethylation to produce CMSC. Further characterization of the cellulose and CMSC were performed using FESEM and DSC. The purity of CMSC was analyzed according to the American Society for Testing and Materials (ASTM) International standards. In this case, acid and alkaline treatments coupled with high-pressure defibrillation were found to be effective in depolymerization and defibrillation of the cellulose fibers. The synthesized CMSC also shows no toxicity in the cell line studies and could be exploited as a pharmaceutical excipient.

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“…Further evidence of the role played by chain flexibility on the non-Newtonian properties of dilute solutions comes from dextran, the archetype of 'true' random coil polysaccharides. For dextran systems, in fact, the lower Newtonian plateau extends to elevated y values, even for high molecular weight samples [24,25].…”

Section: J Steady Shear Viscositymentioning

confidence: 95%

Rheology of polysaccharide systems

Lapasin

Pricl

1995

Rheology of Industrial Polysaccharides: Theory and Applications

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The transport properties and, specifically, the rheological behavior of real and complex materials such as polysaccharide systems can be significantly affected by several factors, mainly related to molecular and supermolecular features. Most of these factors are common to all polymeric systems, as they have universal character; others are peculiar to carbohydrate polymers. If we bear in mind the concepts discussed in §1.4, we can easily imagine for polysaccharides a variety of structural conditions much wider than that generally observed for synthetic polymers. On both molecular and supermolecular scales, polysaccharides possess special characteristics that reflect specific behavior so that different classes of materials can be identified.Let us consider the molecular scale first: at this level, the polymer backbone and its related features, such as its length in solution, shape, stitfuess and the eventual presence of ionizable groups, playa major role in determining the macroscopic properties of the system, including its rheology. Many of these molecular parameters correlate among themselves (e.g. chain stitfuess and length); others must be combined with external factors such as, for instance, the characteristics of the solvent medium. These latter may, in turn, exert an influence on the conformation adopted by the macromolecule in the medium itself, as well as on the possibility of forming supermolecular structures. In other words, changes in ionic strength, the nature of counterions, temperature or other solvent parameters may induce a conformational transition, thus modifying the hydrodynamic resistance of the macromolecule to flow. Also, if the polymer concentration is high enough, the variations described above may promote structural changes at a supermolecular level and, accordingly, modifications in the rheological behavior. Before leaving this brief comment on solvent characteristics we must mention the viscosity although, R. Lapasin et al. (eds.), Rheology of Industrial Polysaccharides: Theory and Applications

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Viscosity of aqueous solutions of polysaccharides and their carboxylate derivatives

Cited by 13 publications

References 14 publications

Hydrodynamic properties of aqueous dextran solutions

Hydrodynamic properties of aqueous dextran solutions

Optimizing Extraction of Cellulose and Synthesizing Pharmaceutical Grade Carboxymethyl Sago Cellulose from Malaysian Sago Pulp

Rheology of polysaccharide systems

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