Carbopol gels: Elastoviscoplastic and slippery glasses made of individual swollen sponges

Piau, Jean‐Michel

doi:10.1016/j.jnnfm.2007.02.011

Cited by 334 publications

(341 citation statements)

References 25 publications

Supporting

Mentioning

314

Contrasting

Unclassified

Order By: Relevance

“…The measurement of the yield stress not only depends on the duration of the experiment, but also on the history of the fluid deformation. In 2007, Piau [46] measured, with MRI-rheometery technique, and compared results for different concentration of Carbopol 940 and 980 at very low shear-rate and found, instead of a yield stress, two Newtonian plateaus. Even if in the yield stress has been questioned as a physical property, the concept of a yield stress still remains very useful for a wide range of applications.…”

Section: Rheometrymentioning

confidence: 99%

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

Cochard

Ancey

2009

Journal of Non-Newtonian Fluid Mechanics

View full text Add to dashboard Cite

a b s t r a c tWe report experimental results related to the dam-break problem for viscoplastic fluids. Using image processing techniques, we were able to accurately reconstruct the free-surface evolution of fixed volumes of fluid suddenly released a plane. We used Carbopol Ultrez 10 as a viscoplastic material; its rheological behavior was closely approximated by a Herschel-Bulkley model for a fairly wide range of shear-rates. Varying the Carbopol concentration allowed us to change the yield stress and bulk viscosity. The yield stress ranged from 78 to 109 Pa, producing Bingham numbers in the 0.07-0.35 range. We investigated the behavior of a 43-kg mass released on a plane, whose inclination ranged from 0 • to 18 • . For each run, we observed that the behavior was nearly the same: at short times, the mass accelerated vigorously on gate opening and very quickly reached a nearly constant velocity. At time t = 1 s, independently of plane inclination and yield stress, the mass reached a near-equilibrium regime, where the front position varied as a power function of time over several decades. We did not observe any run-out phase, during which the mass would have gradually come to a halt. The similarity in the flow behavior made it possible to derive an empirical scaling for the front position in the form x f = t 0.275(sin˛) 1/3 (sin˛) 5/4 , where˛and t denote plane inclination and time, respectively, and which holds for sloping beds (˛> 0).

show abstract

Section: Rheometrymentioning

confidence: 99%

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

Cochard

Ancey

2009

Journal of Non-Newtonian Fluid Mechanics

View full text Add to dashboard Cite

show abstract

“…Our analytical predictions are consequently particularly relevant for cases where simultaneous measurements of these quantities are available, e.g. in foams and emulsions where one has access not only to the frequency dependence of shear and loss moduli 9,25,26,[28][29][30] but also to local observables, like the local stress 51 or the local rheology 11 . Superimposing a small amplitude oscillatory motion orthogonal onto steady shear flow should make it possible to directly estimate the shear-rate dependence of the elastic moduli 52 and compare these to the frequency dependence in pure oscillatory experiments.…”

Section: Resultsmentioning

confidence: 99%

“…The exponent for the shear-rate dependence of the elastic modulus in the elasto-plastic regime has been chosen positive with respect to results on the dependence of the shear modulus in oscillatory experiments on emulsions, foams and gels 9,19,25,27,28 . We expect that a frequency dependence in the steady state of oscillatory experiments translates into a dependence of the shear modulus in the elastic parts of the elasto-plastic flow regime (see sketch of Fig.…”

Section: Shear-dependent Effective Parametersmentioning

confidence: 99%

“…In this analogy the role of the corresponding amplitude that should be considered for the oscillatory case should be played by the typical strain accumulated locally in the elastic parts of the flow regime. It has been shown for emulsions and foams that the dependence of the shear modulus in the low frequency regime is existent but rather weak 19,25,27,28 . On the other hand we expect the typical dissipation time of events to be more sensitive to the value of the applied shear rate and the exponent should have the opposite sign.…”

Section: Shear-dependent Effective Parametersmentioning

confidence: 99%

“…shear and loss moduli have indeed been reported to be frequencydependent, for example in the literature on foams in oscillatory driving experiments on emulsion, foams and gels [25][26][27][28][29][30] . In situations with steadily applied shear, one can expect this frequency dependence to translate to a rate dependence of the local dissipation process and of the steady-state shear modulus G 0 in the elasto-plastic flow regime (see sketch in Fig.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Non-trivial rheological exponents in sheared yield stress fluids

Agoritsas

Martens

2017

Soft Matter

View full text Add to dashboard Cite

In this work we discuss possible physical origins for non-trivial exponents in the athermal rheology of soft materials at low but finite driving rates. A key ingredient in our scenario is the presence of a self-consistent mechanical noise that stems from the spatial superposition of long-range elastic responses to localized plastically deforming regions. We study analytically a mean-field model, in which this mechanical noise is accounted for by a stress diffusion term coupled to the plastic activity. Within this description we show how a dependence of the shear modulus and/or the local relaxation time on the shear rate introduces corrections to the usual mean-field prediction, concerning the Herschel-Bulkley-type rheological response of exponent 1/2. This feature of the mean-field picture is then shown to be robust with respect to structural disorder and partial relaxation of the local stress. We test this prediction numerically on a mesoscopic lattice model that implements explicitly the long-range elastic response to localized shear transformations, and we conclude on how our scenario might be tested in rheological experiments.

show abstract

Fat Plumes May Reflect the Complex Rheology of the Lower Mantle

Davaille

Carrez

2018

Geophysical Research Letters

View full text Add to dashboard Cite

Recent tomographic imaging of the mantle below major hot spots shows slow seismic velocities extending down to the core‐mantle boundary, confirming the existence of mantle plumes. However, these plumes are much thicker than previously thought. Using new laboratory experiments and scaling laws, we show that thermal plumes developing in a visco‐plastic fluid present much larger diameters than plumes developing in a Newtonian fluid. Such a rheology requiring a yield stress is consistent with a lower mantle predominantly deforming by pure dislocation climb. Yield stress values between 1 and 10 MPa, implying dislocation densities between 10 8 and 10 10 m −2 , would be sufficient to reproduce the plumes morphology observed in tomographic images.

show abstract

Carbopol gels: Elastoviscoplastic and slippery glasses made of individual swollen sponges

Cited by 334 publications

References 25 publications

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

Experimental investigation of the spreading of viscoplastic fluids on inclined planes

Non-trivial rheological exponents in sheared yield stress fluids

Fat Plumes May Reflect the Complex Rheology of the Lower Mantle

Contact Info

Product

Resources

About