The activation parameters of viscous flow and the structure of concentrated polymer solutions

Tager, A.A.; Botvinnik, G. O.

doi:10.1016/0032-3950(74)90411-0

Cited by 11 publications

(12 citation statements)

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“…The value of activation entropy is determined using the Eyring relation for the Gibbs flow function [10] NA'h The complexity of the viscosity-temperature dependence follows from the explicit expressions for the density (22) and viscosity coefficient (12); any attempt to obtain a linear approximation will have only restricted validity. The slope of such a dependence is not determined solely by the activation enthalpy, as assumed by Tager and Botvinik [9]. In spite of this, it has been shown in this work that the temperature-depen- functions.…”

Section: (18) Ementioning

confidence: 82%

“…In spite of this, it has been shown in this work that the temperature-depen- functions. An order-of-magnitude estimate of A0, used in [9] as a limiting value for the determination of activation free enthalpy, is clearly inadequate.…”

Section: (18) Ementioning

confidence: 98%

“…(7) is, however, not defined. Tager and Botvinik [9] attempted to determine the thermodynamic activation function of viscous flow by considering the value of A0 in the following relationship [ 10] q = A0 exp (AG*/RT) (8) NA'h…”

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confidence: 99%

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Thermodynamic activation functions of viscous flow of non-polar liquids

Kotas

Valešová

1986

Rheol Acta

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Section: (18) Ementioning

confidence: 82%

Section: (18) Ementioning

confidence: 98%

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Thermodynamic activation functions of viscous flow of non-polar liquids

Kotas

Valešová

1986

Rheol Acta

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“…The viscous flow activation parameters were calculated with the method proposed by Tager [3]. The physicomechanical characteristics of the films were determined on a PMR-1 instrument at a constant strain rate.…”

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confidence: 99%

“…The physicomechanical characteristics of the films were determined on a PMR-1 instrument at a constant strain rate. The parameters of the structural inhomogeneity of the solutions (average radius r of light-scattering regions of the solution) and films were calculated from the turbidity spectrum [3,4], measured on a SF-26 spectrophotometer in the wavelength interval of λ = 420-0580 nm with a 20-nm step.The flow curves of the polymer systems obtained are non-Newtonian in character. In the temperature interval investigated.…”

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confidence: 99%

Viscosity properties of aqueous solutions of carboxymethylcellulose and hydroxyethylcellulose blends

Прусов

Прусова

2007

Fibre Chem

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The possibility of using hydroxyethylcellulose (HOEC) as a modifier polymer for regulating crosslinking processes in Na-carboxymethylcellulose (CMC) solutions was established. The effect of differences in the conformation of the macromolecules of miscible polymers not only on the intensity of intermolecular interaction but also on structuring of the solution was revealed. The decrease in the total concentration of components of the solution and the molecular mass of one of the miscible polymers causes the appearance of individuality of the macromolecules, confirmed by the deviation of the thermodynamic characteristics of viscous flow from additivity.In studying the rheological properties and structure of two-component solutions of sodium carboxymethylcellulose with a different molar mass, it was previously [1] found that the formation of a common supramolecular structure for the components is the cause of the positive deviation of the viscosity from additive values. The possibility of this happening is a function of the conformation of macromolecules of the same chemical nature. The formation of a system of intra-and intermolecular bonds (IMB) to a great degree determines the physicochemical properties of solutions of cellulose ethers and materials based on them. A comparison of the physicochemical properties of solutions of polymer blends (viscosity, structural inhomogeneity, etc.) which are dependent on IMB, where fractions that minimally differ in the intensity of the intermolecular interactions are used as one of the miscible polymers, will allow evaluating the contribution of the conformation of the macromolecules to formation of the system of IMB.Solutions of blends of hydroxyethylcellulose (HOEC) and sodium carboxymethylcellulose (Na-CMC) with a different average degree of polymerization: DP = 12 (I), 916 (II), 1740 (III) but close degree of substitution, i.e., which only differ in the chain length and conformation of the macromolecules, were examined [2]. In discussing the rheological behavior of solutions of the polymer blends, we used the relative deviation of the viscosity and viscous flow activation parameters from additive values. The approach used for the mathematical calculation is discussed in [1].The rheological measurements were performed on a German type PH rotary viscometer in the 293-313 K temperature range. The viscous flow activation parameters were calculated with the method proposed by Tager [3]. The physicomechanical characteristics of the films were determined on a PMR-1 instrument at a constant strain rate. The parameters of the structural inhomogeneity of the solutions (average radius r of light-scattering regions of the solution) and films were calculated from the turbidity spectrum [3,4], measured on a SF-26 spectrophotometer in the wavelength interval of λ = 420-0580 nm with a 20-nm step.The flow curves of the polymer systems obtained are non-Newtonian in character. In the temperature interval investigated. the shape of the flow curves of the solutions did not change. However, for ...

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Rheology of polymeric solutions I. Zero shear conditions

Yasnovsky¹

2002

J of Applied Polymer Sci

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Based on kinetic considerations, the following equation, connecting the zero-shear viscosity of polymeric solutions with temperature and the molecular weight and concentration of the polymer was derived:, where R is relative viscosity (i.e., the ratio of the solution viscosity to the solvent viscosity); K represents a change in enthalpy of viscous flow from a pure solvent to a pure polymer at the same temperature or from a polymer of low molecular weight (M) to one of higher molecular weight, and has the dimensions of energy (e.g., J/mol) because the ratio BM n /(1 ϩ BM n ) is dimensionless; is the volume or molar fraction of a polymer in solution (concentration units can be used in dilute solutions); B is a constant related to the stiffness of the chains of the polymer in a given solvent; and at BM n ϾϾ 1, ln R ϭ K/RT. The equation describes published data on the zero-shear viscosity of four polar and nonpolar polymers in nine solvents with R 2 Ͼ 0.98. This approach allows the use of solutions of moderate concentrations for the characterization of polymers and opens a way for a single-point degree of polymerization (DP) determination of polymers at moderate concentrations if constants K, B, and n of the equation are known.

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The activation parameters of viscous flow and the structure of concentrated polymer solutions

Cited by 11 publications

References 8 publications

Thermodynamic activation functions of viscous flow of non-polar liquids

Thermodynamic activation functions of viscous flow of non-polar liquids

Viscosity properties of aqueous solutions of carboxymethylcellulose and hydroxyethylcellulose blends

Rheology of polymeric solutions I. Zero shear conditions

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