The shear thickening effect in concentrated dispersion systems

Strivens, T. A.

doi:10.1016/0021-9797(76)90226-5

Cited by 61 publications

(20 citation statements)

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“…Scaling of the onset stress with particle size. Onset stress σ * versus particle diameter d for PHSA-stabilised PMMA spheres in this and previous [9,16,[19][20][21][22] work. The solid line is a least-squares fit to a power law σ * = Bd α , with B = 2 × 10 −11 J.m −1.1 and α = −1.9(1).…”

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confidence: 58%

Towards a Unified Description of the Rheology of Hard-Particle Suspensions

2015

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The rheology of suspensions of Brownian, or colloidal, particles (diameter d ≲ 1 µm) differs markedly from that of larger grains (d ≳ 50 µm). Each of these two regimes has been separately studied, but the flow of suspensions with intermediate particle sizes (1 µm ≲ d ≲ 50 µm), which occur ubiquitously in applications, remains poorly understood. By measuring the rheology of suspensions of hard spheres with a wide range of sizes, we show experimentally that shear thickening drives the transition from colloidal to granular flow across the intermediate size regime. This insight makes possible a unified description of the (non-inertial) rheology of hard spheres over the full size spectrum. Moreover, we are able to test a new theory of friction-induced shear thickening, showing that our data can be well fitted using expressions derived from it.Complex fluids, polymers, colloids and surfactant solutions find wide applications, partly because of their highly tuneable behavior under deformation and in flow. The success of the mean-field 'tube' model for polymers [1], which describes how each chain is constrained by thousands of neighbours, means it has long been possible to predict ab initio their linear and non-linear rheology from the molecular topology with very few free parameters. In particular, a scaling description is available of the dependence of rheology on molecular weight.However, progress in suspension rheology has been more difficult [2]. The small number of nearest neighbours (order 10) rules our any mean-field description: local details matter. It is now possible to predict the lowshear viscosity of a suspension of Brownian hard spheres (HS, diameter d ≲ 1 µm) up to volume fractions of φ ≲ 0.6, and the rheology of granular HS (d ≳ 50 µm) is increasingly being studied. Surprisingly, however, how the rheology of HS changes over the whole size spectrum remains unknown, because the behavior in the industriallyubiquitous intermediate size regime, 1 ≲ d ≲ 50 µm, has not been systematically explored. We offer such an exploration in this Letter, and show that the physics bridging the colloidal and the granular regimes is shear thickening.The rheology of colloidal HS is well known [3][4][5]: the viscosity is determined by the particle volume fraction, φ, and the dimensionless shear rate, or Péclet number, Pe (= τ Bγ , the shear rateγ non-dimensionalised by the Brownian time, τ B , needed for a free particle to diffuse its own radius). At Pe ≪ 1 the flow is Newtonian; the viscosity becomes immeasurably large at φ g ≈ 0.58 [5,6]. Shear thinning starts at Pe ≲ 1, reaching a second Newtonian regime at Pe ≫ 1 with a viscosity that diverges at random close packing [2], φ RCP ≈ 0.64, the densest amorphous packing for lubricated (frictionless) HS.Since τ B scales as d 3 , granular HS inhabit the Pe ≫ 1 regime at all practical shear rates. Extrapolating naïvely from the above description of colloidal flow, one expects Newtonian behaviour with a viscosity diverging at φ RCP . Experiments do find a Newtonian viscosity, but i...

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Towards a Unified Description of the Rheology of Hard-Particle Suspensions

2015

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“…Strivens ( 1976) reported that different rheometers gave different results and that unstable stress readings interfered with his measurements. In view of our results this was probably due to wall slip and cluster formation.…”

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confidence: 99%

“…With concentrated dispersions of monodisperse particles, however, a discontinuous jump in the viscosity can occur with increasing shear rate (Hoffman, 1972;Wagstaff and Chaffey, 1977;Boersma et al, 1990). Especially at shear rates in the neighborhood of this critical shear-rate rheopectic (Willey and Macosko, 1978) and thixotropic (Hoffman, 1982;Strivens, 1976) behavior have been observed. In measurements of flow curves this time dependency is sometimes avoided as much as possible by performing fast measurements ( Hotbnan, private communication 1.…”

Section: Introductionmentioning

confidence: 99%

Time‐dependent behavior and wall slip in concentrated shear thickening dispersions

Boersma

Baets

Lavèn

et al. 1991

Journal of Rheology

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SynopsisThe viscosity of concentrated shear thickening dispersions was measured as a function of shear rate, Couette cylinder size, and time. The level of the low shear rate viscosity, which was found to be independent of system size and time, could bc predicted by the equation of Frankel and Acrivos. At shear rates above the critical shear rate for shear thickening in highly concentrated (#> 0.57) dispersions of monodispcrse particles strong viscosity instabilities were detected, together with a dependence on cylinder size. The instabilities are attributed to reversible order-disorder transitions, e.g., from strings to clusters. This dependence on cylinder size is due to wall slip, slipping planes in the dispersion, and even plug flow in the gap. With less concentrated or polydisperse dispersions the effects are much less severe but there is thixotropy, probably due to a reordering of the dispersion.

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“…which were shear-thickening under steady flow conditions (16). In his results, a transition from a high dynamic viscosity, low elastic modulus (G') region at low frequencies to a low dynamic viscosity, high G' region at high frequencies can be observed.…”

Section: -9797/92 $300mentioning

confidence: 87%

Viscoelastic properties of concentrated shear-thickening dispersions

Boersma

Lavèn

Stein

1992

Journal of Colloid and Interface Science

119

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The viscoelastic properties of electrostatically stabilized concentrated dispersions of silica and of glass particles in a glycerol/water mixture are studied by oscillatory shear measurements. These dispersions are shear-thickening in steady shear flow. At most frequencies the loss modulus is found to dominate the storage modulus. At certain critical combinations of deformation amplitude and frequency the response signal becomes distorted, containing higher harmonics. This phenomenon can be ascribed to flow blockage, closely related to shear thickening in steady shear flow. When plotting the critical deformation against the frequency, three different regions can be detected. At low frequencies there is the steady shear flow limit, at intermediate frequencies double-layer overlap causes nonlinearity in the response signal, and at high frequencies there is a region where the critical deformation for flow blockage is a system-dependent function of the frequency, but is independent of the volume fraction. The magnitudes of the storage moduli are found to be in reasonable agreement with theoretical predictions.

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The shear thickening effect in concentrated dispersion systems

Cited by 61 publications

References 13 publications

Towards a Unified Description of the Rheology of Hard-Particle Suspensions

Towards a Unified Description of the Rheology of Hard-Particle Suspensions

Time‐dependent behavior and wall slip in concentrated shear thickening dispersions

Viscoelastic properties of concentrated shear-thickening dispersions

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