Dynamics of transient vorticity-aligned structures and internal stresses in shear thickening colloidal gels

Citation:

Osuji, C. O. ; Weitz, D. A. Dynamics of transient vorticity-aligned structures and internal stresses in shear thickening colloidal gels. In Xvth International Congress on Rheology - the Society of Rheology 80th Annual Meeting, Pts 1 and 2; Co, A. ; Leal, L. G. ; Colby, R. H. ; Giacomin, A. J., Ed.; 2008; Vol. 1027, pp. 680-682. Copy at http://www.tinyurl.com/kzz4snw

Abstract:

Dilute dispersions of fractal particles in hydrocarbon solvents flocculate and form gels with typical scaling of elasticity with particle volume fraction. Surprisingly, these attractive systems display shear thickening in two distinct regimes. At low shear rates, shear thickening is concurrent with the formation of stable vorticity-aligned structures. At high shear rates, shear thickening involves the breakdown of dense particle clusters into smaller aggregates. Pre-shear within the high shear rate shear thickening regime leads to enhanced modulus gels where storage modulus scales as a power law with the pre-shear stress. Shear-rate quenches from shear thickening flows into the quiescent state result in rapid gelation accompanied by slowly decaying internal stresses. Deformation of these mechanically quenched gels is highlighted by the transient formation of highly anisotropic vorticity aligned structures and the relaxation of residual internal stresses.

Notes:

Times Cited: 2 15th International Congress on Rheology/80th Annual Meeting of the Society-of-Rheology Aug 03-08, 2008 Monterey, CA Soc Rheol