Graduate Program in Physics at UFSC, Florianópolis

THE PHYSICS GRADUATE PROGRAM invites everyone to the seminar:

A Mode Coupling Theory for the Rheology of Colloidal Glasses

Dr. Christian P. Amann
Universität Konstanz

Abstract:

“What is a glass?” Starting from the Smulochowsky equation, mode coupling theory (MCT) is a powerful tool to approximate the collective dynamics of simple liquids near their glass transition via the dynamics of density fluctuations. It provides conceptual answers for the opening question and yields a qualitative and quantitative description of glassy dynamics in and out-of equilibrium. In this work, MCT with integration through the transient dynamics (ITT) was used to calculate the rheological response of a dense colloidal dispersion to start-up shear flow. It is possible to predict the whole range of non-monotonous stress response from the elastic,
via the transient, into the steady state (and to compare to experiments). The distortion of the structure-factor can also be calculated and a close connection between the distortion symmetry and the non-monotonous stress response is observed, which can provide an interpretation for the microscopic processes involved. The concept, applied to hard-sphere colloids, can be generalized to other short-range interaction potentials, once the equilibrium structure factor, as only input quantity needed, is provided.

Date: 11/July/2014 – (friday) – Place: Sala 212 – Auditório do Departamento de Física – Time: 10h:15min