Residual stresses and shear-induced overaging in boehmite gels

Abstract

Colloidal gels respond like soft solids at rest, whereas they flow like liquids under external shear. Starting from a fluidized state under an applied shear rate ${\dot{\gamma }}_p$, abrupt flow cessation triggers a liquid-to-solid transition during which the stress relaxes towards a so-called \textit{residual stress} ${\sigma }_{\mathrm{res}}$ that tallies a macroscopic signature of previous shear history. Here, we report on the liquid-to-solid transition in gels of boehmite, an aluminum oxide, that shows a remarkable non-monotonic stress relaxation towards a residual stress ${\sigma }_{\mathrm{res}}({\dot{\gamma }}_p)$ characterized by a dual behavior relative to a critical value ${\dot{\gamma }}_c$ of the shear rate ${\dot{\gamma }}_p$. Following shear at ${\dot{\gamma }}_p>{\dot{\gamma }}_c$, the gel obtained upon flow cessation is insensitive to shear history, and the residual stress is negligible. However, for ${\dot{\gamma }}_p<{\dot{\gamma }}_c$, the gel encodes some memory of the shear history, and ${\sigma }_{\mathrm{res}}$ increases for decreasing shear rate, directly contributing to reinforcing the gel viscoelastic properties. Moreover, we show that both ${\sigma }_{\mathrm{res}}$ and the gel viscoelastic properties increase logarithmically with the strain accumulated during the shear period preceding flow cessation. Such a shear-induced "overaging" phenomenon bears great potential for tuning the rheological properties of colloidal gels.

5 pages, 4 figures

References in corpus (4)

• Shear Thickening and Scaling of the Elastic Modulus in a Fractal Colloidal System with Attractive Interactions
• Shear-induced memory effects in boehmite gels
• Shape anisotropy enhances the elasticity of colloidal gels through mechanisms that act multiplicatively
• Memory in Non-Monotonic Stress Response of an Athermal Disordered Solid

Cited by in corpus (8)

• Ductile-to-brittle transition and yielding in soft amorphous materials: perspectives and open questions
• New insights on carbon black suspension rheology -- anisotropic thixotropy and anti-thixotropy
• Three length scales colloidal gels: the clusters of clusters versus the interpenetrating clusters approach
• Tuning residual stress, directional memory and aging in soft glassy materials
• Shear-induced reinforcement in boehmite gels: a rheo-X-ray-scattering study
• Rheological Behavior of Colloidal Silica Dispersion: Irreversible Aging and Thixotropy
• Shear-driven memory effects in carbon black gels
• Slow dynamics and time-composition superposition in gels of cellulose nanocrystals