Paper Number
GG15 

Session
Out of Equilibrium Systems: Gels and Glasses

Title
The linear viscoelastic spectrum and non-affine rearrangements in soft particulate gels

Presentation Date and Time
October 22, 2019 (Tuesday) 9:50

Track / Room
Track 7 / Room 306C

Authors (Click on name to view author profile)

1. Bantawa, Minaspi (Georgetown University, Department of Physics)
2. Bouzid, Mehdi (Universite Paris Sud)
3. Keshavarz, Bavand (MIT, Mechanical Engineering)
4. Geri, Michela (MIT, Mechanical Engineering)
5. Divoux, Thibaut (MIT,CNRS)
6. McKinley, Gareth H. (Massachusetts Institute of Technology, Department of Mechanical Engineering)
7. Del Gado, Emanuela (Georgetown University, Department of Physics)

Author and Affiliation Lines (in printed abstract book)
Minaspi Bantawa¹, Mehdi Bouzid², Bavand Keshavarz³, Michela Geri³, Thibaut Divoux⁴, Gareth H. McKinley³, and Emanuela Del Gado^1
1Department of Physics, Georgetown University, Washington, DC 20007; ²Universite Paris Sud, Orsay, France; ³Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA; ⁴MIT,CNRS, Cambridge, MA 02139

Speaker / Presenter 
Bantawa, Minaspi

Text of Abstract
We have investigated the connection between the structural and mechanical heterogeneities of soft particulate gels and their linear viscoelastic spectrum in a 3-D microscopic numerical model, using large scale simulations with Optimally Windowed Chirp (OWCh) signals. In the model, particles spontaneously self-assemble into disordered, stable porous networks (even at low volume fractions) that feature extended relaxation spectra, microscopic dynamics, and mechanics consistent with several observations in colloidal and protein gels. To recapitulate the basic features of the particle contacts in those systems, the main ingredients of the model are short-range attractive interactions and bending stiffness for the inter-particle bonds. We will analyze how the shape of the frequency-dependent dynamic modulus G*(ω) varies with the solid volume fraction and the age of the gels and how it is connected to the distribution of microscopic non-affine rearrangements the network experiences under small-amplitude oscillatory deformation. We will show that the changes in the relaxation spectrum can be captured by the parameters of a fractional constitutive model and discuss how the underlying changes of the microscopic dynamical processes determine the rheological response.