Memory effects in Soft Glassy Materials
| When |
Oct 05, 2020
from 11:00 to 12:00 |
|---|---|
| Where | Amphi Descartes (D2) |
| Attendees |
Thibaut Divoux |
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Soft Glassy Materials (SGM) are ubiquitous in major industries, i.e., foodstuff, personal care, and oil. These soft solids are composed of subunits such as particles or polymers, whose interaction and volume fraction control their viscoelastic properties. An additional control parameter is provided by processing, i.e., the route followed in manufacturing or synthesizing SGM. Indeed, external shear often comes to compete with the attractive interactions that drive the gelation, affecting the gel’s microstructure, which encodes the gel’s shear history. Such a “memory effect” raises crucial fundamental issues about the physics at play during flow-microstructure interactions.
In this talk, we will discuss various aspects of shear-induced memory effects in colloidal gels. First, I will illustrate a way to quantify the gel’s memory through the so-called rheological hysteresis. Second, I will show that flow cessation – i.e., the decreasing branch of the rheological hysteresis – can be used to tune the microstructural and mechanical properties of gels. Experiments performed with various cessation rates allow us to prepare a gel in different states of microstructure and elasticity linked by a remarkable power-law scaling. Finally, I will discuss how this preparation protocol impacts the yielding dynamics of gels and the resulting pattern formation.