Paper Number
GG9 

Session
Arrested Systems: Gels and Glasses

Title
Microscopic origins of non-exponential stress relaxations in arrested soft materials

Presentation Date and Time
October 11, 2021 (Monday) 2:45

Track / Room
Track 6 / Ballroom 1

Authors (Click on name to view author profile)

  1. Song, Jake (Massachusetts Institute of Technology)
  2. Zhang, Qingteng (Argonne National Laboratory)
  3. de Quesada, Felipe (Massachusetts Institute of Technology)
  4. Rizvi, Mehedi H. (North Carolina State University)
  5. Ilavsky, Jan (Argonne National Laboratory, Advanced Photon Source)
  6. Tracy, Joseph B. (North Carolina State University)
  7. Narayanan, Suresh (Argonne National Laboratory)
  8. Leheny, Robert L. (Johns Hopkins University)
  9. Del Gado, Emanuela (Georgetown University)
  10. Holten-Andersen, Niels (Massachusetts Institute of Technology)
  11. McKinley, Gareth H. (Massachusetts Institute of Technology, Mechanical Engineering)

Author and Affiliation Lines (in printed abstract book)
Jake Song1, Qingteng Zhang2, Felipe de Quesada1, Mehedi H. Rizvi3, Jan Ilavsky2, Joseph B. Tracy3, Suresh Narayanan2, Robert L. Leheny4, Emanuela Del Gado5, Niels Holten-Andersen1 and Gareth H. McKinley1
1Massachusetts Institute of Technology, Cambridge, MA; 2Argonne National Laboratory, Lemont, IL; 3North Carolina State University, Raleigh, NC; 4Johns Hopkins University, Baltimore, MD; 5Georgetown University, Washington, DC

Speaker / Presenter 
Song, Jake

Keywords
experimental methods; colloids; composites; gels; glasses

Text of Abstract
Non-exponential stress relaxation processes occur ubiquitously in arrested soft materials such as glasses, colloidal suspensions, and biological networks. Despite this ubiquity, the microscopic origins of such relaxation processes remain unclear. Here, we directly study this phenomenon through a combination of rheology and x-ray photon correlation spectroscopy on a model arrested gel. By investigating the microscopic relaxation processes in the gel in quiescent and in driven conditions, we find that these slow relaxation processes are governed by an interplay of microscopic fluctuations in the elastic stresses accrued during arrest, and of the elastic avalanches generated by small mechanical perturbations onto the system. We thus show that non-exponential stress relaxations in strongly arrested materials are a signature of non-linear relaxation processes governed by internal stress heterogeneities, and a manifestation of the fractal potential energy landscapes underlying such materials.