Paper Number
TM25 

Session
Rheometry: Advanced Techniques and Methods

Title
Weakly-nonlinear viscoelastic rheometry

Presentation Date and Time
October 22, 2019 (Tuesday) 4:10

Track / Room
Track 1 / Room 305A

Authors (Click on name to view author profile)

  1. Ewoldt, Randy H. (University of Illinois at Urbana-Champaign, Department of Mechanical Science and Engineering)
  2. Martinetti, Luca (University of Illinois at Urbana-Champaign, Department of Mechanical Science and Engineering)
  3. Carey-De La Torre, Olivia (University of Illinois at Urbana-Champaign, Department of Mechanical Science and Engineering)
  4. Singh, Piyush K. (University of Illinois at Urbana-Champaign, Department of Chemical And Biomolecular Engineering)
  5. Schweizer, Kenneth S. (University of Illinois at Urbana-Champaign, Department of Materials Science and Engineering)
  6. Natalia, Irene (KU Leuven, Soft Matter, Rheology and Technology Section)
  7. Koos, Erin (KU Leuven, Soft Matter, Rheology and Technology Section)

Author and Affiliation Lines (in printed abstract book)
Randy H. Ewoldt1, Luca Martinetti1, Olivia Carey-De La Torre1, Piyush K. Singh1, Kenneth S. Schweizer2, Irene Natalia3, and Erin Koos3
1Department of Mechanical Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801; 2Department of Materials Science and Engineering, University of Illinois at Urbana-Champaign, Urbana, IL 61801; 3Soft Matter, Rheology and Technology Section, KU Leuven, Leuven, Belgium

Speaker / Presenter 
Ewoldt, Randy H.

Text of Abstract
Weakly-nonlinear excitations are a fundamental characterization technique used in optics, acoustics, heat transfer, and other fields, but rheometry methods have comparatively lagged in this area. Here we describe our work to develop a paradigm of weakly-nonlinear viscoelastic rheometry that has allowed for experimental and theoretical advances with significant implications for microstructure inference and insight. For example, recently our group collaborated [1] to use MAOS measurements with a novel asymptotically-nonlinear viscoelastic model and the Polymer Reference Interaction Site Model (PRISM) to settle a 70-year debate and infer the nonlinear mechanisms of a reversible polymer network. Application to different soft matter microstructures demonstrates that the weakly-nonlinear regime is a type of "sweet spot," nonlinear enough to provide additional information, but still amenable to theoretical predictions. This is demonstrated with our work on transient polymer networks, polymer melts, soft glassy colloidal suspensions, and capillary suspensions which show anomalous power law scaling. Our recent developments in MAOS make it easier for experimentalists to generate new observations, which in turn provides theorists more opportunities to derive statistical mechanical theories to relate structure to rheology based on the weakly-nonlinear viscoelastic behavior of materials. [1] Martinetti, L., O. Carey-De La Torre, K. S. Schweizer, and R. H. Ewoldt, “Inferring the nonlinear mechanisms of a reversible network,” Macromolecules, 51 (21), 8772–8789 (2018). https://doi.org/10.1021/acs.macromol.8b01295