Colloidal gels are versatile materials used in a wide range of technologies, and are often subject to transient, nonlinear deformations during either processing or final consumer use. In this study, the rheology and microstructural evolution of dilute, depletion-induced colloidal gels undergoing shear-induced yielding (and ultimately flow) are investigated using quantitative time-resolved confocal microscopy and rheometry to probe the complex interplay between the thermodynamic and hydrodynamic interparticle interactions and globally applied stresses.  We report that dilute gels yield via a two-step process that is qualitatively similar to dense, weakly attractive glasses, but through necessarily distinct mechanisms. The implications of this behavior include a remarkable effective �strengthening� at large strains that increases the dilute gel's resistance to subsequent shear deformation.

Two-step yielding in dilute colloidal gels

243rd National Meeting (2012)

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