Paper Number
SM23 

Session
Polymers Solutions, Melts and Blends

Title
Stretched Polymer Physics, Extensional Rheology and Free Surface Flows

Presentation Date and Time
October 11, 2022 (Tuesday) 11:30

Track / Room
Track 2 / Sheraton 3

Authors (Click on name to view author profile)

  1. Dinic, Jelena (Argonne National Laboratory, Materials Science Division and Center for Molecular Engineer)
  2. Martinez, Carina (University of Illinois Chicago, Department of Chemical Engineering)
  3. Jimenez, Leidy N. (University of Illinois at Chicago, Chemical Engineering)
  4. Slykas, Cheryl (University of Illinois at Chicago)
  5. Kubinski, Alexander (University of Illinois at Chicago, Chemical Engineering)
  6. Al-Breiki, Fahed (University of Illinois at Chicago, Chemical Engineering)
  7. Sharma, Vivek (University of Illinois Chicago, Department of Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Jelena Dinic1, Carina Martinez2, Leidy N. Jimenez2, Cheryl Slykas2, Alexander Kubinski2, Fahed Al-Breiki2 and Vivek Sharma2
1Materials Science Division and Center for Molecular Engineer, Argonne National Laboratory, Lemont, IL 60439; 2Department of Chemical Engineering, University of Illinois Chicago, Chicago, IL

Speaker / Presenter 
Sharma, Vivek

Keywords
experimental methods; theoretical methods; polymer solutions

Text of Abstract
Characterization of extensional viscosity, extensional relaxation time and finite extensibility effects, as well as macromolecular properties that determine pinch-off dynamics of unentangled polymer solutions are beyond capabilities of conventional shear and extensional rheology techniques in which free surface flows are absent. Here we show that dripping-onto-substrate (DoS) rheometry protocols we developed recently can be used for measuring extensional viscosity and extensional relaxation time of polymeric complex fluids, including low viscosity printing inks and polymer solutions that are beyond the measurable range of commercially-available capillary break-up extensional rheometer (CaBER). Using DoS rheometry protocols that involve visualization and analysis of capillary-driven thinning and pinch-off dynamics of a columnar neck formed between a nozzle and a sessile drop, we elucidate the stretched polymer hydrodynamics underlying observed rheological response and processing behavior of polymeric complex fluids. We discover that our pursuit involves myriad, intertwined quests and insights into conformation-dependent hydrodynamic and excluded volume interactions, Pincus’ tension blobs, finite extensibility effects, as well as coil-stretch transition and hysteresis. We find that the extensional relaxation times exhibit concentration dependence distinct from shear rheology response or anticipated by blob models developed for relaxation of weakly perturbed chains. We show that the influence of molecular weight and chemistry can be evaluated a priori, using three macromolecular parameters: flexibility, extensibility and segmental dissymmetry for neutral polymers. Finally, we characterize and analyze the pinch-off dynamics of charged polymers and ionic surfactant–neutral polymer complexes in the presence of varying salt concentration, to elucidate the influence of complex interplay of electrostatic and hydrodynamic stretching of macromolecules on processability.