Configuration and hydrodynamic properties of fully acetylated guaran

Koleske, Joseph V.; Kurath, Sheldon F.

doi:10.1002/pol.1964.100020930

Cited by 14 publications

(14 citation statements)

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“…The lengths of rod, model, and polymer are calculated to be 52, 52, and 50 A at DP 10 and 62,59, and 58 A at DP 12. The Porod-Kratky persistence length [25] defined as the projection of an infinitely long chain on the direction of its first link, was found [26] by means of the Ptitsyn-Eizner viscosity equation [27] to vary between 55 and 59 A for p-1,4 linked cellulose acetate [28], glucomannan acetate [29], and galactomannan triacetate [30], in good agreement with the result in Figure 4.…”

Section: The End-to-end Lengths Calculated From the Axial Ratiosupporting

confidence: 70%

Viscosity and the prolate ellipsoid model applied to low molecular weight cellulose triacetate fractions

Swenson¹,

Carlson²,

Kaustinen³

1971

J. polym. sci., C Polym. symp.

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Cellulose triacetate of molecular weight 5,600, obtained by acetolysis, and separated into 15 fractions by preparative permeation chromatography, was analyzed for intrinsic viscosity, number average, and weight average molecular weight. Glucose pentaacetate, cel‐lobiose octaacetate, and cellotriose hendecaacetate are also included in the analysis. The axial ratios of a prolate ellipsoid calculated from the viscosity of the low DP CT A fractions, when compared to a molecular model and to the fully extended contour length, confirm the persistence length found by viscosity theory at high molecular weight levels. A long plateau region of slope 0.28 to ca. DP 8, is found in the log‐log [n] versus DPn plot. The curve then rises sharply to slope ca. 2.0 at DPn 10 and declines again to slope ca. 0.9 above DP 30. A close correspondence is found with the hydrodynamic predictions of Peterlin [5, 16] for short‐chain wormlike or inflexible polymers. Plots of R2/DPn versus DPn for CTA and CA show that coil randomness is apparently not achieved before DP 400. No change in viscosity was detectable for CTA of DP 50, when increasing amounts of nonsolvent isopropyl alcohol were added to 1,2‐dichloroethane, short of the precipitation point.

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Section: The End-to-end Lengths Calculated From the Axial Ratiosupporting

confidence: 70%

Viscosity and the prolate ellipsoid model applied to low molecular weight cellulose triacetate fractions

Swenson¹,

Carlson²,

Kaustinen³

1971

J. polym. sci., C Polym. symp.

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“…Of the cellulosic polymers, the only available data for GGM in water appear to be those of Deb and Mukherjee (1963) on a single commercial sample; in Table 1, entry 11 gives their reported M , and an RG calculated from their dissymmetry data. Some results from a detailed study of the guarantriacetate-acetonitrile system (Koleske and Kurath, 1964) are given in entries 12 and 13, the different Mark-Houwink constants apparently reflecting a change in the GTA random-coil from partially free-draining for N < 1900 to nonfree-draining for N > 1900. Interestingly, when RG is plotted against N , Deb and Mukherjee's (1963) point for GGM-water accords well with Koleske and Kurath's (1964) data for GTA-acetonitrile.…”

Section: /Amentioning

confidence: 99%

“…Some results from a detailed study of the guarantriacetate-acetonitrile system (Koleske and Kurath, 1964) are given in entries 12 and 13, the different Mark-Houwink constants apparently reflecting a change in the GTA random-coil from partially free-draining for N < 1900 to nonfree-draining for N > 1900. Interestingly, when RG is plotted against N , Deb and Mukherjee's (1963) point for GGM-water accords well with Koleske and Kurath's (1964) data for GTA-acetonitrile. Table 1, entry 14, lists the results obtained by Brown, Henley, and Ohman (1963) for fractionated samples of HEC in water.…”

Section: /Amentioning

confidence: 99%

Drag reduction fundamentals

1975

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Drag reduction by dilute solutions of linear, random-coiling macromolecules in turbulent pipe flow is reviewed. The experimental evidence is emphasized in three sections concerned with the graphical display of established features of the phenomenon, data correlation and analysis, and the physical mechanism of drag reduction. P. S. VlRK Deportment of Chemical Engineering Indian Institute of TechnologyMadras 600036, India SCOPEOur objective is to acquaint the reader with the phenomenon of drag reduction, in which the skin friction caused by turbulent flow of an ordinary liquid is reduced by additives. This phenomenon, discovered ahnut 1947, has received attention because it suggests practical benefits, such as increased pipeline capacities and faster ships, and is also theoretically stimulating, in the areas of wall turbulence and molecular rheology . This review, restricted to drag reduction by polymer solutions in pipe flow, has three sections: (1) the experimental evidence, (2) correlation and analysis, and (3) mechanism. Section 1 presents experimentally established results showing the flow regimes exhibited by polymer solutions, the relationships among flow and macromolecular parameters, and the changes in mean and turbulent flow structures which accompany drag reduction. The conclusions of Section 1 are documented in Section 2. The latter concerns the empirical correlation of experimental results, with analysis (and tabulations) of the data used for this purpose. Section 2 also provides for discussion of evidence not fully enough established to be included in Section 1. Finally, in Section 3 an attempt is made to physically interpret the experimental results, to infer the nature of the polymer-turbulence interaction responsible for drag reduction and its effect on the energy balances of turbulent pipe flow. CONCLUSIONS AND SIGNIFICANCE1. Gross Flow. Drag reduction by dilute polymer solutions in turbulent pipe flow appears bounded between two universal asymptotes, namely, the Prandtl-Karman law [Equation (2)] for Newtonian turbulent flow and a maximum drag reduction asymptote [Equation (4)]. Between these limits is a polymeric regime in which the observed friction factor relations are approximately linear on Prandtl-Karman coordinates and can be characterized by two parameters-the wall shear stress at the onset of drag reduction and the slope increment by which the polymer solution slope exceeds Newtonian. For a given polymer species-solvent pair: The onset wall shear stress is essentially independent of pipe diameter, polymer concentration, and solvent viscosity, and varies inversely as the two to three power of polymer radius of gyration [Equations (19) and ( 5 ) ] . The slope increment is essentially independent of pipe diameter, varies as the square root of polymer concentration, and as the three-halves power of the number of chain links in the polymer backbone [Equation (S)], and seems unaffected by decreases in polymer excluded volume.2. Mean Velocity Profiles. On law of the wall coordinates, these posse...

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“…Koleske and Kurath [101] have reported a detailed study of solutions of galactomannan acetates. Sharman et al [84] made a comparison of the hydrodynamic properties of solutions of galactomannans from Leguminosae and guar, and of naturally occurring galactomannans and industrially useful, synthetic, watersoluble cellulose derivatives (hydroxyethyl cellulose and ethylhydroxy cellulose).…”

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confidence: 98%

Seed Galactomannans: An Overview

Srivastava

Kapoor

2005

Chemistry & Biodiversity

283

152

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Seed galactomannans are vegetable, heterogeneous polysaccharides widely distributed in nature. Generally, they possess (1-->4)-linked D-mannopyranose (Man) main chains to which are attached (1-->6)-linked D-galactopyranosyl (Gal) units. The Man/Gal ratios differ from gum to gum, resulting in a change in structure, which, in turn, determines the various industrial applications of seed galactomannans. These materials are important in paper, textile, petroleum-drilling, pharmaceutics, food, cosmaceutics, and explosives industries. In this review, the biodiversified applicability of galactomannan gums is discussed, particularly with respect to structural aspects, properties, human consumption, and technical applications. Especially important is that the solution properties (rheological behaviour, viscosity, emulsifying tendency, etc.) of natural and chemically modified galactomannans can be tuned by interaction with other (carbohydrate-based) monomers or polymers.

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Configuration and hydrodynamic properties of fully acetylated guaran

Cited by 14 publications

References 61 publications

Viscosity and the prolate ellipsoid model applied to low molecular weight cellulose triacetate fractions

Viscosity and the prolate ellipsoid model applied to low molecular weight cellulose triacetate fractions

Drag reduction fundamentals

Seed Galactomannans: An Overview

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