Paper Number
GG42 

Session
Rheology of Gels, Glasses and Jammed Systems

Title
Residual stresses and shear-induced overaging in boehmite gels

Presentation Date and Time
October 12, 2022 (Wednesday) 1:50

Track / Room
Track 3 / Sheraton 5

Authors (Click on name to view author profile)

  1. Sudreau, Iana (ENSL, CNRS, Laboratoire de physique)
  2. Auxois, Mathilde (ENSL, CNRS, Laboratoire de physique)
  3. Servel, Marion (IFP Energies nouvelles)
  4. Lécolier, Eric (IFP Energies nouvelles)
  5. Manneville, Sébastien (ENSL, CNRS, Laboratoire de physique)
  6. Divoux, Thibaut (ENSL, CNRS, Laboratoire de physique)

Author and Affiliation Lines (in printed abstract book)
Iana Sudreau1, Mathilde Auxois1, Marion Servel2, Eric Lécolier2, Sébastien Manneville1 and Thibaut Divoux1
1ENSL, CNRS, Laboratoire de physique, Lyon, France; 2IFP Energies nouvelles, Solaize, France

Speaker / Presenter 
Divoux, Thibaut

Keywords
experimental methods; colloids; gels; suspensions

Text of 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 ġp, abrupt flow cessation triggers a liquid-to-solid transition during which the stress relaxes towards a so-called residual stress σres 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 σres(ġp) characterized by a dual behavior relative to a critical value ġc of the shear rate ġp. Following shear at ġp>ġc, the gel obtained upon flow cessation is insensitive to shear history, and the residual stress is negligible. However, for ġp<ġc, the gel encodes some memory of the shear history, and σres increases for decreasing shear rate, directly contributing to reinforcing the gel viscoelastic properties. Moreover, we show that both σres 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.