Foams, Emulsions & Interfacial Rheology

Single droplet interfacial measurements using microfluidic extensional flows

October 17, 2018 (Wednesday) 3:45

Track 6 / Tanglewood

(Click on name to view author profile)

  1. Narayan, Shweta (University of Minnesota, Mechanical Engineering)
  2. Moravec, Davis B. (Donaldson Company)
  3. Hauser, Brad G. (Donaldson Company)
  4. Dallas, Andrew J. (Donaldson Company)
  5. Dutcher, Cari S. (University of Minnesota, Mechanical Engineering)

(in printed abstract book)
Shweta Narayan1, Davis B. Moravec2, Brad G. Hauser2, Andrew J. Dallas2, and Cari S. Dutcher1
1Mechanical Engineering, University of Minnesota, Minneapolis, MN 55455; 2Donaldson Company, Bloomington, MN 55431

Narayan, Shweta

Micron-sized droplets, dispersed in complex oil-water emulsions, can be challenging to separate using conventional coalescing techniques. The presence of surfactants which lower interfacial tension between the dispersed and continuous phases further increases the difficulty to coalesce and separate these droplets. In previous work, we show using a dynamic microfluidic tensiometer, that the timescale for equilibration of dynamic interfacial tension scales strongly with droplet size. In addition to lowering interfacial tension, surface-active components confer viscoelastic properties to the oil-water interface. The most popular methods for measuring interfacial rheological properties include the double-wall ring geometry for interfacial shear rheology, and oscillating bubble technique or the more recently developed microtensiometer by Alvarez et al. for dilatational rheology. Here, we employ a microfluidic platform with an extensional flow field coupled with shape oscillation analysis for performing interfacial measurements on complex oil-water interfaces. This technique will be applied towards measuring interfacial rheological properties of complex liquid-liquid interfaces. These measurements will provide fundamental insights into the rheological behavior of complex interfaces in emulsions, at length and time scales relevant to liquid-liquid separation applications