Power law rheology of soft glassy and gelled materials
By: Pedro Patrício
From: ISEL
At: Faculdade de Ciências, Ed. C8, 8.2.06
[2015-05-07]
In this seminar, we will firstly examine the fundamental aspects that may lead to the the universal weak power law behaviours of the elastic and viscous moduli with the angular frequency of the oscillatory deformation,
G'(w) ∼ G''(w) ∼ wα, (0 < α < 1),Â
that occur in a wide variety of soft materials, including living cells.
This will help us to understand not only the reason for their universality, but also the reason for the large number of possible theoretical microscopic models that are able to explain them.
Next, we will describe two important types of microscopic models. The first, based on a generalised Maxwell model, retains the fluid properties of the soft glassy materials above the glass transition. The second, based on a generalised Kelvin-Voigt model, retains a more solid or gelled character. We will see that these two models, even though they have parallel descriptions, they translate essentially different microscopic physical systems.
