Influence of medium viscosity and adsorbed polymer on the reversible shear thickening transition in concentrated colloidal dispersions

Shenoy, Sudhir; Wagner, Norman J.

doi:10.1007/s00397-004-0418-z

Cited by 65 publications

(39 citation statements)

References 38 publications

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“…In such cases it is often said that the shear thickening evolves from continuous to discontinuous shear thickening with increasing packing fraction. So-called Discontinuous Shear Thickening (DST) has the most dramatic increase in viscosity of any type of shear thickening, and includes the prototypical example of cornstarch in water as well as many other densely packed hardparticle suspensions (Barnes, 1989;Bender and Wagner, 1996;Bertrand et al, 2002;Boersma et al, 1990;Brown and Jaeger, 2009;Brown et al, 2010a,b;Egres and Wagner, 2005;Egres et al, 2006;Fall et al, 2008;Frith et al, 1996;Hoffman, 1972Hoffman, , 1974Hoffman, , 1982Laun, 1994;Lee and Wagner, 2006;Lootens et al, 2003Lootens et al, , 2005Wagner, 2001a,b, 2002;Metzner and Whitlock, 1958;O'Brien and Mackay, 2000;Shenoy and Wagner, 2005), and solutions of micelles (Hofmann et al, 1991;Liu and Pine, 1996). An example of the evolution from continuous to discontinuous shear thickening with packing fraction is shown in Fig.…”

Section: B Discontinuous Shear Thickeningmentioning

confidence: 99%

Shear thickening in concentrated suspensions: phenomenology, mechanisms and relations to jamming

2014

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Shear thickening is a type of non-Newtonian behavior in which the stress required to shear a fluid increases faster than linearly with shear rate. Many concentrated suspensions of particles exhibit an especially dramatic version, known as Discontinuous Shear Thickening (DST), in which the stress suddenly jumps with increasing shear rate and produces solid-like behavior. The best known example of such counter-intuitive response to applied stresses occurs in mixtures of cornstarch in water. Over the last several years, this shear-induced solid-like behavior together with a variety of other unusual fluid phenomena has generated considerable interest in the physics of densely packed suspensions. In this review, we discuss the common physical properties of systems exhibiting shear thickening, and different mechanisms and models proposed to describe it. We then suggest how these mechanisms may be related and generalized, and propose a general phase diagram for shear thickening systems. We also discuss how recent work has related the physics of shear thickening to that of granular materials and jammed systems. Since DST is described by models that require only simple generic interactions between particles, we outline the broader context of other concentrated many-particle systems such as foams and emulsions, and explain why DST is restricted to the parameter regime of hard-particle suspensions. Finally, we discuss some of the outstanding problems and emerging opportunities.

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Section: B Discontinuous Shear Thickeningmentioning

confidence: 99%

Shear thickening in concentrated suspensions: phenomenology, mechanisms and relations to jamming

2014

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“…1. Stress scales: The boundaries of the shear thickening regime are simply described in terms of stress scales (rather than shear rate) which are mostly independent of packing fraction (Maranzano and Wagner, 2001a;Shenoy and Wagner, 2005;Brown and Jaeger, 2009) and liquid viscosity (Boersma et al, 1990;Frith et al, 1996). Consequently, the onset shear rate varies with packing fraction and liquid viscosity since suspension viscosities increase with both parameters (Brady and Bossis, 1985).…”

Section: Introductionmentioning

confidence: 99%

The role of dilation and confining stresses in shear thickening of dense suspensions

Brown¹,

Jaeger²

2012

Journal of Rheology

289

341

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Many densely packed suspensions and colloids exhibit a behavior known as Discontinuous Shear Thickening in which the shear stress jumps dramatically and reversibly as the shear rate is increased. We performed rheometry and video microscopy measurements on a variety of suspensions to determine the mechanism for this behavior. We distinguish Discontinuous Shear Thickening from inertial effects by showing that the latter are characterized by a Reynolds number but are only found for lower packing fractions and higher shear rates than the former. Shear profiles and normal stress measurements indicate that, in the shear thickening regime, stresses are transmitted through frictional rather than viscous interactions, and come to the surprising conclusion that for concentrated suspensions such as cornstarch in water which exhibit the phenomenon of Discontinuous Shear Thickening, the local constitutive relation between stress and shear rate is not necessarily shear thickening. If the suspended particles are heavy enough to settle we find the onset stress of shear thickening τmin corresponds to a hydrostatic pressure from the weight of the particle packing where neighboring particles begin to shear relative to each other. Above τmin, dilation is seen to cause particles to penetrate the liquid-air interface of the sheared sample. The upper stress boundary τmax of the shear thickening regime is shown to roughly match the ratio of surface tension divided by a radius of curvature on the order of the particle size. These results suggest a new model in which the increased dissipation in the shear thickening regime comes from frictional stresses that emerge as dilation is frustrated by a confining stress from surface tension at the liquid-air interface. We generalize this shear thickening mechanism to other sources of a confining stress by showing that, when instead the suspensions are confined by solid walls and have no liquid-air interface, τmax is set by the stiffness of the most compliant boundary which frustrates dilation. All of this rheology can be described by a non-local constitutive relation in which the local relation between stress and shear rate is shear thinning, but where the stress increase comes from a normal stress term which depends on the global dilation.

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“…As the shear rate or strain amplitude increases, the hydrodynamic force grows and some of the aggregations are disturbed to result in the decrease in viscosity and the shear-thinning to appear. In the case that the hydrodynamic force predominates over the repulsive interactions, the clusters are formed and block the flow of the fluid [18] . The formation of the clusters may be related to the concentration of suspension.…”

Section: Discussionmentioning

confidence: 99%

Rheological responses of fumed silica suspensions under steady and oscillatory shear

Yang

Ruan

Zou

et al. 2009

Sci. China Ser. E-Technol. Sci.

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Rheological experiments under steady and oscillatory shear were conducted for fumed silica suspensions in polyethylene glycol. Under steady shear the shear-thinning and thickening response were exhibited and the flow exponent N was determined. With the increase of concentration the flow exponent N showed a rapid increase, and it increased dramatically when the discontinuous shear-thickening took place. Oscillatory shear experiments were conducted at constant frequency and constant amplitude strain, respectively. The shear-thinning and the discontinuous shear-thickening behavior were observed under different constant frequencies from 10 to 80 rad/s. The correlation between complex modulus (G * ) and sweep frequency (ω) was illuminated at γ =750%. It was found that the correlation between G * and ω could be fitted by equation: G * ∝ω n . The indexes in shear-thinning region and shear-thickening were determined. The indexes were similar to some extent at shear-thinning region and increased dramatically to a much higher value when the shear-thickening occurred，especially at higher weight fractions. The behaviors can be qualitatively explained as follows: the shear-thinning owes to decrease of viscosity, which results from disruption of the aggregates; the cluster theory attributes the shear-thickening to the formation of metastable, flow induced clusters, which block the system.

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Influence of medium viscosity and adsorbed polymer on the reversible shear thickening transition in concentrated colloidal dispersions

Cited by 65 publications

References 38 publications

Shear thickening in concentrated suspensions: phenomenology, mechanisms and relations to jamming

Shear thickening in concentrated suspensions: phenomenology, mechanisms and relations to jamming

The role of dilation and confining stresses in shear thickening of dense suspensions

Rheological responses of fumed silica suspensions under steady and oscillatory shear

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