Polymers in contraction flow: a predictive model for polymer scission in porous media?

Peter Olmsted, Sandeep Garrepally, Stephane Jouenne, Francois Lequeux,

Georgetown University, Washington DC, USA

Abstract

Polymer scission in extensional flow arises during drug injection, spraying and printing, and oilfield harvesting. We revisit this old problem using specially-designed microfluidic hyperbolic contraction flows, in which the ratio of the pressure drop of a polymer solution to that of the (Newtonian) solvent has a maximum due to the competition between polymer extension and degradation (scission). From the dependence of the pressure maximum on flow rate and molecular weights we can quantify the decrease in equivalent molecular weight due scission. We find a geometry-dependent quasi-universal relation between the flow rates at which the maximum occurs for successive passage in a given contraction, which appears to be independent of molecular weight, concentration, solvent quality and viscosity, and can be used to predict degradation under successive passes. I will discuss what we can learn about the the details of the scission kinetics in flow from these observations.

---

To register for the Complex Fluids Seminar Series announcements by E-mail, please send a plain text e-mail message to <mjrdomo (at) math.ubc.ca> with the following content: subscribe fluid-mech-seminar To unsubscribe, send: unsubscribe fluid-mech-seminar