Flow-structure relationship of shear-thickening surfactant solutions

Abstract

The shear-thickening transition in dilute surfactant solutions is investigated using rheology and small-angle neutron scattering. Steady shear experiments on a new thickening system, the tosylate of cethyltrimethylammonium, revealed a continuous increase of the apparent viscosity above a critical strain rate γc. Concentration and temperature variations of γc are derived, and the former is found to be in contradiction with a theoretically predicted gelation. From the scattering under shear, we establish a clear correlation between flow and structure. In the thickening region, the patterns are due to the superposition of two coexisting states, one viscoelastic entangled sheared network and one still purely viscous made of short aggregates. At higher γ, the former state dominates and its increasing orientation results in shear-thinning.

Ultrasound velocimetry in a shear-thickening wormlike micellar solution: Evidence for the coexistence of radial and vorticity shear bands

“…In most of the experimental works dealing with surfactant systems, it has been argued that a strong flowstructure coupling induces new organizations like nematic phases or onion textures or other flow-induced phenomena [14,[44][45][46][47]. With the evolution of these new structures, the systems exhibit a stress plateau in steadystate flow curve (τ vs.γ), which in the case of present seeded material would be τ c = 10 Pa.…”

Shear-thickening transition in surfactant solutions: New experimental features from rheology and flow birefringence

“…It is now established that a prerequisite for the shear thickening is that the amphiphile molecules self-assemble in the quiescent state into locally cylindrical micelles. The shear thickening has been observed in solutions of rodlike aggregates in the dilute regime (case i) [1][2][3][4][5][6][7] but also in solutions of wormlike micelles in the entangled regime (case ii) [4,5,[8][9][10][11][12][13]. Interestingly, some characteristic features of the transition are similar for rodlike and wormlike assemblies.…”

“…Starting from the quiescent state, when a solution is sheared atγ >γ c , an induction time t I is necessary to induce the viscous state. It has been reported by several authors [1,3,5,6,15] that t I increases considerably when the applied shear rate approachesγ c (keepinġ γ >γ c ). A dependence of the form t I ∼γ −1 has been proposed [1,9].…”

“…Under steady shear however, above a critical strain rate notedγ c the shear viscosity increases, as a new and more viscous phase develops in the cell. The shear-induced phase (SIP) has been thoroughly investigated by rheological measurements [1][2][3][4][5][6][7][8]11], flow-birefringence [3,5,14] and small-angle neutron scattering [2][3][4]6]. The two latter techniques revealed a strong degree of alignment of this new phase with respect to the flow velocity.…”

Shear Rate and Permeability in Water Flooding

“…Thus, although somewhat characterised for flow in tubes and cells, where shear rate is well defined, there has been no analysis for flow in porous media. (Berret et al 1998). The application within permeable flow-particularly the extremely non-regular anisotropic oil reservoirs-is more problematic because of a lack of a mapping of permeability to the shear rate (and thus to the generated viscosity change which determines the flow).…”