Doctoral Dissertations

Keywords and Phrases

Disjoining pressure

Abstract

"The kinetics of spreading of thin liquid films on a solid substrate in the presence of constraints has been studied here. The internal constraint appears in the form of dissolved polymers which cause the solution to be non wetting or only partially wetting. The polymer is assumed to be non-adsorbing. The fluid flow is governed by the Laplace pressure and the disjoining pressure. A detailed formulation has been solved using a numerical scheme and results have been presented for two cases of thin films with and without dissolved polymers. Both these cases have further been analyzed in the presence and absence of evaporation effects. The external constraint is that of the film pinned to a slot. The results explain well experimental observations by other researchers who observed that drops of polymer solutions spread with rates similar to setting liquids and then suddenly stopped to equilibrate. It is seen that the contact line becomes pinned in the presence of evaporation effects.

The study of dilute polymer solution used in the above cases has been extended to larger polymer concentrations using experiments where droplets are allowed to spread and dry. Based on observations, it is concluded that the knowledge of the mobility of the contact line plays a very important role in predicting the spreading behavior of solutions and these observations have been presented here.

For spreading of solutions on a model rough surface, it is seen that the numerical solutions collapse. An analysis of the edge of the drop near the contact line is sought by equating the surface work to the rate of viscous dissipation. Instabilities in the system that give rise to Haines' jumps, and the stick-slip phenomenon have been discussed and are plausible explanations for the collapse seen in the numerical scheme"--Abstract, page iii.

Advisor(s)

Neogi, P. (Partho), 1951-

Committee Member(s)

Wang, Jee C.
Henthorn, David
Isaac, Kakkattukuzhy M.
Bekker, Miron

Department(s)

Chemical and Biochemical Engineering

Degree Name

Ph. D. in Chemical Engineering

Sponsor(s)

National Science Foundation (U.S.)

Publisher

University of Missouri--Rolla

Publication Date

Fall 2006

Pagination

vii, 67 pages

Note about bibliography

Includes bibliographical references (pages 64-66).

Rights

© 2006 Saritha Sathyanarayanan, All rights reserved.

Document Type

Dissertation - Restricted Access

File Type

text

Language

English

Subject Headings

Chemical kineticsThin filmsWetting

Thesis Number

T 9064

Print OCLC #

173218445

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