Three length scales colloidal gels: the clusters of clusters versus the interpenetrating clusters approach

Abstract

Typically, in quiescent conditions, attractive colloids at low volume fractions form fractal gels structured into two length scales: the colloidal and the fractal cluster scales. However when flow interfere with gelation colloidal fractal gels may display three distinct length scales [Dagès, et al., Soft Matter 18, 6645 (2022)]. Following those recent experimental investigations, we derive two models that account for the structure and the rheological properties of such atypical colloidal gels. The gel elasticity is inferred from scaling arguments and the structure is translated into scattering intensities following the global scattering functions approach proposed by Beaucage and typically measured in small angle X-ray scattering (SAXS). In both models, we consider that the colloids condensate into fractal clusters. In the clusters of clusters model, the clusters form superagregates which then build the gel network. In the interpenetrating clusters model, the clusters interpenetrate one-another to form the gel network. Those two models are then utilised to analyse rheo-SAXS experiments carried out on carbon black gels formed through flow cessation. The results of the analysis vouch for the clusters of clusters model with a densification of the structures as the gel characteristic length scales increase.

References in corpus (16)

• Shear Banding of Complex Fluids
• Theory of activated-rate processes under shear with application to shear-induced aggregation of colloids
• Timescales in creep and yielding of attractive gels
• Diffusion- and reaction-limited cluster aggregation revisited
• Simultaneous rheo-electric measurements of strongly conductive complex fluids
• Time dependence in large amplitude oscillatory shear: a rheo-ultrasonic study of fatigue dynamics in a colloidal gel
• Shear-driven solidification of dilute colloidal suspensions
• Multiple yielding processes in a colloidal gel under large amplitude oscillatory stress
• Rheo-acoustic gels: Tuning mechanical and flow properties of colloidal gels with ultrasonic vibrations
• Shear induced tuning and memory effects in colloidal gels of rods and spheres
• Residual stresses and shear-induced overaging in boehmite gels
• Shear-induced memory effects in boehmite gels
• Interpenetration of fractal clusters drives elasticity in colloidal gels formed upon flow cessation
• Unexpected decoupling of stretching and bending modes in protein gels
• Mechanics and structure of carbon black gels under high-power ultrasound
• Proposition of extension of models relating rheological quantities and microscopic structure through the use of a double fractal structure

Cited by in corpus (4)

• Attractive carbon black dispersions: structural and mechanical responses to shear
• Shear-induced reinforcement in boehmite gels: a rheo-X-ray-scattering study
• Tuning the mechanical properties of organophilic clay dispersions: particle composition and preshear history effects
• Shear-driven memory effects in carbon black gels