Nuclear magnetic resonance visualization of anomalous flow in cone-and-plate rheometry

Britton, Melanie M.; Callaghan, Paul T.

doi:10.1122/1.550846

Cited by 85 publications

(74 citation statements)

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“…This formation of local spatially-inhomogeneous shear bands has been experimentally observed by NMR imaging [79,80], neutron scattering [81,82] and other flow imaging diagnostics [38,[83][84][85][86][87][88][89].…”

Section: Steady Shear Flowmentioning

confidence: 72%

Nonlinear shear and extensional flow dynamics of wormlike surfactant solutions

Yeşilata

Clasen

McKinley³

2006

Journal of Non-Newtonian Fluid Mechanics

143

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Section: Steady Shear Flowmentioning

confidence: 72%

Nonlinear shear and extensional flow dynamics of wormlike surfactant solutions

Yeşilata

Clasen

McKinley³

2006

Journal of Non-Newtonian Fluid Mechanics

143

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“…In some (diluted and concentrated) worm-like systems, wall slip is reported (Manneville et al 2007;Salmon et al 2003b). Gradient banding is also reported to occur in entangled polymers (Callaghan and Gil 2000;Britton and Callaghan 1997a;Tapadia et al 2006), micellar cubic phases (Eiser et al 2000a, b), supra-molecular polymer solutions (van der Gucht et al 2006), transient networks (Michel et al 2001), and thermotropic side chain liquid crystal polymers (Pujolle-Robic et al 2002). Experiments indicate that gradient banding can also occur in hexagonal phases of surfactant solutions (Ramos et al 2000).…”

Section: Gradient Bandingmentioning

confidence: 88%

Gradient and vorticity banding

2008

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"Banded structures" of macroscopic dimensions can be induced by simple shear flow in many different types of soft matter systems. Depending on whether these bands extend along the gradient or vorticity direction, the banding transition is referred to as "gradient banding" or "vorticity banding," respectively. The main features of gradient banding can be understood on the basis of a relatively simple constitutive equation. This minimal model for gradient banding will be discussed in some detail, and its predictions are shown to explain many of the experimentally observed features. The minimal model assumes a decrease of the shear stress of the homogeneously sheared system with increasing shear rate within a certain shear-rate interval. The possible microscopic origin of the severe shear-thinning behaviour that is necessary for the resulting nonmonotonic flow curves is discussed for a few particular systems. Deviations between experimental observations and predictions by the minimal model are due to obvious simplifications within the scope of the minimal model. The most serious simplifications are the neglect of concentration dependence of the shear stress (or on other degrees of freedom) and of the elastic contributions to the stress, normal stresses, and the possibility of shear-induced phase transitions. The consequences of coupling of stress and concentration will be analyzed in some detail. In contrast to predictions of the minimal model, when coupling to concentration is important, a flow instability can occur that does not require strong shear thinning. Gradient banding is sometimes also observed in glassy-and gel-like systems, as well as in shear-thickening systems. Possible mechanisms that could be at the origin of gradient-band formation in such systems are discussed. Gradient banding can also occur in strongly entangled polymeric systems. Banding in these systems is discussed on the basis of computer simulations. Vorticity banding is less well understood and less extensively investigated experimentally as compared to gradient banding. Possible scenarios that are at the origin of vorticity banding will be discussed. Among other systems, the observed vorticity-banding transition in rod-like col-loids is discussed in some detail. It is argued, on the basis of experimental observations for these colloidal systems, that the vorticity-banding instability for such colloidal suspensions is probably related to an elastic instability, reminiscent of the Weissenberg effect in polymeric systems. This mechanism might explain vorticity banding in discon-tinuously shear-thickening systems and could be at work in other vorticity-banding systems as well. This overview does not include time-dependent phenomena like oscillations and chaotic behaviour.

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“…However, opinions are different on the formation mechanism of SIS. Hu et al [10,11] considered that the SISs only nucleate homogeneously throughout the whole shear cell in an intermediate range of shear stresses, whereas it is further preferred that the shearthickening progresses thoroughly nonhomogenously in all situations [17,20,28,29]. Furthermore, for low-concentration solutions, some experiments [8,30,31] have proved that shear-thickening may be a kind of nonequilibrium shearinduced phase transition.…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, for low-concentration solutions, some experiments [8,30,31] have proved that shear-thickening may be a kind of nonequilibrium shearinduced phase transition. However, it has also been suggested that hydrodynamic instabilities may play an important role in the shear-thickening behaviour [17,20,28,29]. Olmsted and Lu [32], as well as Porte et al [33], attempted to develop theories which incorporate ideas about nonequilibrium phase transitions and hydrodynamic instabilities.…”

Section: Resultsmentioning

confidence: 99%

Time-Dependent Shear-Induced Nonlinear Viscosity Effects in Dilute CTAC/NaSal Solutions: Mechanism Analyses

Wei

2014

Advances in Mechanical Engineering

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The time-dependent shear-induced nonlinear viscosity effects of dilute surfactant solutions (CTAC/NaSal) at constant shear rate were tested by using the rheometer Couette cell. The apparent viscosity evolution curve can be divided into five stages: weak shearthickening (Stage I), weak shear-thinning and plateau (Stage II), sharp shear-thickening (Stage III), oscillating adjustment (Stage IV), and rough plateau (Stage V). In Stage I, the stretching effects of shear flow lead to the weak increase in apparent viscosity at the inception of shearing. The apparent viscosity curve firstly decreases in Stage II and then levels off. The apparent viscosity plateau is caused by the forming and slipping of micellar lumps at the inner cylinder wall surface. Once the volume of lump exceeds a certain degree, the nucleation process of forming SIS is triggered, which is the beginning of Stage III and then the apparent viscosity increases sharply. The variations of apparent viscosity in adjusting period are rather complicated in Stage IV, and the variations mainly depend on the situation of SISs network. In Stage V, coupled with obvious oscillations, the apparent viscosity maintains a basically constant plateau value, indicating that the SISs network is fully developed and saturated at the corresponding shear rate.

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Nuclear magnetic resonance visualization of anomalous flow in cone-and-plate rheometry

Cited by 85 publications

References 0 publications

Nonlinear shear and extensional flow dynamics of wormlike surfactant solutions

Nonlinear shear and extensional flow dynamics of wormlike surfactant solutions

Gradient and vorticity banding

Time-Dependent Shear-Induced Nonlinear Viscosity Effects in Dilute CTAC/NaSal Solutions: Mechanism Analyses

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