Force-Based Dynamic Contact Angle Measurements in Liquid-Liquid-Solid Systems

Abstract

Under flow conditions, the dynamic contact angle replaces the equilibrium contact angle. Correlation of dynamic contact angles as a function of the capillary number in liquid-liquid-solid systems is important in a number of applications. For instance, it is one of the ways used to predict water penetration into an oil-filled porous medium. The Cahn-Thermo device is used to measure the excess force needed to plunge a plate vertically into a liquid-liquid interface or pull it out. This force is used to calculate the dynamic contact angle. Polydimethylsiloxane (PDMS) with different viscosities were used for the upper phase and water for the lower phase (viscosity ratios of 95-485). An algebraic expression that predicts the dynamic contact angles has been derived using the concept that the total viscous dissipation is equal to the surface work in the contact line region. This result, together with a result based on a regular hydrodynamic theory, was compared to the experiments on the advancing dynamic contact angles. The advancing dynamic contact angles measured were from 90° to 105°, agreed with the theory and one adjustable parameter related to the ratio of microscopic to the macroscopic length scale that is recovered is found to depend inversely on the viscosity ratio. The parameter itself varies from 2 to 70. The receding contact angles showed significant scatter. A closer photographic examination showed the meniscus to be unstable.

Department(s)

Chemical and Biochemical Engineering

Second Department

Geosciences and Geological and Petroleum Engineering

Keywords and Phrases

Contact Line Instability; Dynamic Wetting; Liquid-Liquid Systems; Wettability; Contact Angle; Polydimethylsiloxane; Polymer Blends; Porous Materials; Rolling Resistance; Silicones; Viscosity; Adjustable Parameters; Contact Line Regions; Contact Lines; Dynamic Contact Angle; Liquid-Liquid Interfaces; Polydimethylsiloxane PDMS; Phase Interfaces

International Standard Serial Number (ISSN)

0920-4105

Document Type

Article - Journal

Document Version

Citation

File Type

text

Language(s)

English

Rights

© 2016 Elsevier B.V., All rights reserved.

Publication Date

01 Nov 2016

Link to Full Text

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