Paper Number
MM7 

Session
Microrheology and Microfluidics

Title
Investigating the dynamics of droplet-breakup in a microfluidic cross-slot device for characterizing the extensional properties of weakly viscoelastic fluids

Presentation Date and Time
October 10, 2017 (Tuesday) 10:40

Track / Room
Track 6 / Aspen

Authors (Click on name to view author profile)

1. Marshall, Kristin A. (Oregon State University)
2. Haug, Shelley R. (Oregon State University)
3. Walker, Travis W. (Oregon State University, CBEE)

Author and Affiliation Lines (in printed abstract book)
Kristin A. Marshall, Shelley R. Haug, and Travis W. Walker
CBEE, Oregon State University, Corvallis, OR 97331

Speaker / Presenter 
Walker, Travis W.

Text of Abstract
Dilute and semi-dilute polymer solutions are used in a wide range of applications. In these processes, small amounts of macromolecule are added to enhance the performance of the working fluid, and regardless of being a desired outcome or not, the presence of elasticity may significantly impact the fluid response to a disturbance, particularly in extension. The present research was conducted in an effort to make improvements to and to provide an in-depth assessment of the techniques available for characterizing low-viscosity elasticity. A microfluidic device is presented that uses a cross-slot geometry to observe a two-phase droplet breakup event. For viscoelastic fluids, we report that a cylindrical filament forms between droplet segments which appears to decay exponentially in time. In optically tracking this decay, both transient extensional viscosity and relaxation times can be evaluated. For validating and optimizing the device, a range of poly(ethylene oxide) (PEO) and Newtonian solutions were tested. Comparisons of the evolution profiles as a result of the presence of elasticity are made, and these results are compared with the results from other emerging extensional techniques.