Date of Award

12-2012

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Legacy Department

Materials Science and Engineering

Advisor

Kornev, Konstantin G

Committee Member

Ellison , Michael

Committee Member

Luzinov , Igor

Committee Member

Groff , Richard

Abstract

This research is centered on the analysis of static and dynamic effects of wetting of single capillaries and fibers. We discuss specifics of the capillary rise and drop-on-fiber techniques and develop new methods of characterization of surface energy of single fibers when its contact angle varies between zero and ninety degrees. The contact angles were evaluated and compared for different substrates. We study the dynamics of the meniscus formation inside and outside of capillaries and fibers. We develop a mathematical model of liquid uptake by capillaries and analyze the factors affecting liquid uptake. The derived fundamental equation describes the dynamics of the fluid uptake by thin porous materials where spontaneous uptake takes milliseconds to fill the pore. We show that the effects of apparent mass, gravity, and air resistance can be neglected. The scaling analysis reveals four different regimes of liquid flow that can be classified by a dynamic 'phase diagram'. This phase diagram can guide the design of porous absorption materials. The theoretical 'phase diagram' was checked against experiments on spontaneous liquid uptake. We tracked the meniscus position inside single capillary tubes of different sizes, experimentally checked the influence of different forces on liquid uptake such as gravity and air resistance forces and compared the results with the theoretical predictions. The constructed phase diagram allows the materials scientist to control the uptake kinetics by choosing the liquid/solid pair with a suitable contact angle, viscosity, surface tension and pore size.

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