Paper Number
VP38 

Session
Pre-recorded Flash Presentations (virtual)

Title
Extensional rheology and pinching dynamics of associative polysaccharide solutions

Presentation Date and Time
All Week (Asynchronous) Any Time

Track / Room
Pre-recorded Presentation / Virtual

Authors (Click on name to view author profile)

  1. Lu, Xinyu (PPG Industries)
  2. Martíne, Carina (University of Illinois at Chicago, Department of Chemical Engineering)
  3. Dinic, Jelena (University of Illinois at Chicago, Department of Chemical Engineering)
  4. Wang, Chao (PPG Industries)
  5. Sun, Hao (PPG Industries)
  6. Rearick, Brian (PPG Industries)
  7. Sharma, Vivek (University of Illinois at Chicago, Chemical Engineering)

Author and Affiliation Lines (in printed abstract book)
Xinyu Lu1, Carina Martíne2, Jelena Dinic2, Chao Wang1, Hao Sun1, Brian Rearick1 and Vivek Sharma2
1PPG Industries, Allison Park, PA; 2Chemical Engineering, University of Illinois at Chicago, Chicago, IL 60607

Speaker / Presenter 
Lu, Xinyu

Keywords
experimental methods; applied rheology; colloids; non-Newtonian fluids; polymer solutions; rheology methods

Text of Abstract
Coating formulations often exhibit complex rheological behavior due to the contributions and interactions of dissolved polymers, pigments, and particles. Understanding the response extensional flows of such non-Newtonian fluids is critical to the performance of coatings, in spraying, jetting and rolling applications, where streamwise velocity gradients spontaneously arise in pinching necks. Associative polysaccharides are widely used as rheology modifiers in industrial aqueous-based formulations. In this talk, we contrast the shear and extensional rheology response of hydrophobically-modified hydroxyethyl cellulose (hmHEC, Mw = 300 kg/mol) as a sticky polymer with the bare chain of a higher molecular weight HEC (Mw = 720 kg/mol) via Dripping-onto-Substrate (DoS) rheometry protocols. We show that sticker associations enhance zero shear viscosity and relaxation time (elasticity), and both quantities display stronger concentration-dependent variation for sticky polymers. Striking differences are observed in neck shapes, radius evolution profiles, and extensional viscosity plotted as a function of strain as well as strain rate. We present a comprehensive analysis of changes in pinching dynamics, concentration-dependent variation in steady, terminal viscosity as well as filament lifespan as a function of concentration for the sticky polymer and describe the influence of multiple stickers on the macromolecular strain, relaxation, and dynamics of associative polysaccharides.