Please use this identifier to cite or link to this item: http://hdl.handle.net/2445/24847
Title: Rheological behavior of hydrophobically modified hydroxyethyl cellulose solutions: A linear viscoelastic model
Author: Maestro Garriga, Alicia
González, C.
Gutiérrez González, José María, 1953-
Keywords: Reologia
Cel·lulosa
Viscoelasticitat
Polímers
Solucions (Química)
Rheology
Cellulose
Viscoelasticity
Polymers
Solution (Chemistry)
Issue Date: 2002
Publisher: The Society of Rheology
Abstract: The rheological behavior of hydrophobically modified hydroxyethyl cellulose HMHEC, an associative thickener, was studied and compared with that of hydrophobically modified ethoxylated urethanes HEURs and nonassociative celluloses. In contrast to HEURs, a simple Maxwell model does not fit the linear viscoelastic behavior of HMHEC. Differences are attributed to the stiffness and comb structure of HMHEC. A generalized Maxwell model with a logarithmic distribution of relaxation times is proposed, and another parameter that includes Rouse-like relaxation is added to fit behavior at high frequencies. Four parameters are needed to describe HMHEC viscoelasticity: a mean relaxation time, lM ; its corresponding standard deviation, s; a plateau modulus, GN ; and a viscosity at infinite frequency, h ` . Satisfactory fitting is obtained for all concentrations and temperatures in the range of frequencies studied. The sharp increase of GN with concentration indicates loop-to-bridge transitions. Temperature does not influence GN , since the reduction in the number density of elastically effective chains caused by Brownian motion masks the direct effect of temperature. The dependence of lM on temperature follows the Arrhenius equation, as does the relaxation time of HEURs, but it does not change with concentration, presumably because the comb structure of HMHEC prevents the formation of long superchains.
Note: Reproducció del document publicat a: http://dx.doi.org/10.1122/1.1427910
It is part of: Journal of Rheology, 2002, vol. 46, p. 127-143
Related resource: http://dx.doi.org/10.1122/1.1427910
URI: http://hdl.handle.net/2445/24847
ISSN: 0148-6055
Appears in Collections:Articles publicats en revistes (Enginyeria Química i Química Analítica)

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