Suspension rheology under oscillatory shear and its geophysical implications

Suspension rheology under oscillatory shear and its geophysical implications

Glass transitions and shear thickening suspension rheology

We introduce a class of simple models for shear thickening and/or ‘‘jamming’’ in colloidal suspensions. These are based on the schematic mode coupling theory ~MCT! of the glass transition, having a memory term that depends on a density variable, and on both the shear stress and the shear rate. ~Tensorial aspects of the rheology, such as normal stresses, are ignored for simplicity.! We calculate...

Rheology of concentrated xanthan gum solutions: Oscillatory shear flow behavior

Using a strain-controlled rheometer, the dynamic viscoelastic properties of aqueous xanthan gum solutions with different concentrations were measured over a wide range of strain amplitudes and then the linear viscoelastic behavior in small amplitude oscillatory shear flow fields was investigated over a broad range of angular frequencies. In this article, both the strain amplitude and concentrat...

The rheology and microstructure of branched micelles under shear

The rheology and shear-induced structures of a series of self-assembled surfactant worm-like micelles (WLMs) with varying levels of branching are measured using rheoand flow-small angle neutron scattering (SANS). The degree of branching in the mixed cationic/anionic surfactant (CTAT/SDBS) WLMs is controlled via the addition of the hydrotropic salt sodium tosylate and verified by cryo-TEM. The l...

Unifying suspension and granular rheology.

Using an original pressure-imposed shear cell, we study the rheology of dense suspensions. We show that they exhibit a viscoplastic behavior similarly to granular media successfully described by a frictional rheology and fully characterized by the evolution of the friction coefficient μ and the volume fraction ϕ with a dimensionless viscous number I(v). Dense suspension and granular media are t...