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Titolo:
LOW-SHEAR VISCOSITY OF ISOTROPIC DISPERSIONS OF (BROWNIAN) RODS AND FIBERS - A REVIEW OF THEORY AND EXPERIMENTS
Autore:
WIERENGA AM; PHILIPSE AP;
Indirizzi:
DEBYE RES INST,VANT HOFF LAB PHYS & COLLOID CHEM,PADUALAAN 8 NL-3584 CH UTRECHT NETHERLANDS DEBYE RES INST,VANT HOFF LAB PHYS & COLLOID CHEM NL-3584 CH UTRECHT NETHERLANDS
Titolo Testata:
Colloids and surfaces. A, Physicochemical and engineering aspects
fascicolo: 1-3, volume: 137, anno: 1998,
pagine: 355 - 372
SICI:
0927-7757(1998)137:1-3<355:LVOIDO>2.0.ZU;2-X
Fonte:
ISI
Lingua:
ENG
Soggetto:
STIFF-CHAIN POLYMERS; RODLIKE POLYMERS; CONCENTRATED-SOLUTIONS; RHEOLOGICAL PROPERTIES; DILUTE SUSPENSIONS; ROTATIONAL DIFFUSION; SPHERICAL-PARTICLES; SEMIDILUTE SOLUTION; NONDILUTE SOLUTIONS; MOLECULAR-WEIGHT;
Keywords:
COLLOIDAL RODS; DOI-EDWARDS THEORY; ISOTROPIC DISPERSIONS; KRIEGER-DOUGHERTY EQUATION; LOW-SHEAR VISCOSITY; QUEMADA-MODEL;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Science Citation Index Expanded
Citazioni:
109
Recensione:
Indirizzi per estratti:
Citazione:
A.M. Wierenga e A.P. Philipse, "LOW-SHEAR VISCOSITY OF ISOTROPIC DISPERSIONS OF (BROWNIAN) RODS AND FIBERS - A REVIEW OF THEORY AND EXPERIMENTS", Colloids and surfaces. A, Physicochemical and engineering aspects, 137(1-3), 1998, pp. 355-372

Abstract

A review is presented of the low-shear theology of isotropic rod dispersions. Various theoretical descriptions are compared, and trends in experiments on a variety of rods and rodlike polymers are identified and discussed. For dilute dispersions, the intrinsic viscosity [eta] isonly a function of the rod dimensions and hardly depends on specific system characteristics like chain flexibility, weak colloidal attractions, Brownian motion and surface roughness. For a large range of aspect ratios (20 < r < 1000), the asymptotic result of Onsager: [eta] approximate to (4r(2)/15 In r) predicts intrinsic viscosities surprisinglywell. At higher particle concentrations though, the shear viscosity is dominated by specific interactions between the rods. For Brownian rods, the semi-empirical ''Krieger-Dougherty'' equation predicts the viscosity fairly well. The dramatic effect of deviations from hard-rod interactions can be modelled by adapting the isotropic volume fraction at which the low-shear viscosity diverges. The viscosity data of non-Brownian fibres are better described by the ''Quemada'' or ''Maron-Pierce'' equation. Experiments on well-defined (inorganic) model colloids are needed to quantify the concentration-dependence of the low-shear viscosity for rod dispersions. Theoretical calculations are still incapable of predicting this dependence. (C) 1998 Elsevier Science B.V.

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Documento generato il 04/12/20 alle ore 21:53:47