Paper Number
IR13
Session
Interfacial Rheology
Title
A novel and non-invasive method for shear interfacial rheology measurements
Presentation Date and Time
October 10, 2022 (Monday) 4:05
Track / Room
Track 5 / Sheraton 2
Authors
- Venerus, David C. (New Jersey Institute of Technology, Chemical & Materials Engineering)
Author and Affiliation Lines
David C. Venerus
Chemical & Materials Engineering, New Jersey Institute of Technology, Newark, NJ 07102
Speaker / Presenter
Venerus, David C.
Keywords
interfacial rheology
Text of Abstract
Surfactants at gas-liquid and liquid-liquid interfaces have profound effects on stresses within the interface, which in turn influence flow in bulk phases. These effects include changes in interfacial tension, and the development of extra stresses that arise when the interface is deformed. In recent years, there has been a surge in research attempting to understand the relation between interfacial stress and deformation, or interfacial rheology. A number of approaches have been developed to measure the rheological properties of interfaces subjected to shear deformations. So-called direct techniques involve imposing a deformation by placing a solid probe at the interface and measuring the force or torque required to move the solid (or keep it stationary). These probes need to be small, which leads to a Boussinesq number that is larger than unity, in order to measure interfacial rheological properties such viscosity or modulus. However, these probes have dimensions that are several orders of magnitude larger than the thickness of the interfacial region being investigated making these techniques inherently invasive. Here, we describe an indirect technique for interfacial shear rheology measurements that does not involve the contact of a solid probe (or surface) with the interface. The technique is based on a novel feature of the time-dependent flow induced by a rotating cone. The feasibility of the approach is demonstrated with calculations for interfaces having linear and non-linear rheological behaviors, which suggest this method can be used for small Boussinesq number systems.