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Title:Formation of uniform particles: Morphology and colloidal stability, and stable particle growth during precipitation from titanium alkoxides
Author(s):Look, Jee-Loon
Doctoral Committee Chair(s):Zukoski, Charles F.
Department / Program:Chemical and Biomolecular Engineering
Engineering, Chemical
Engineering, Materials Science
Discipline:Chemical Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Chemistry, Physical
Engineering, Chemical
Engineering, Materials Science
Abstract:The mechanisms of formation of uniform particles from hydrolysis and condensation of titanium alkoxides are investigated. Evidence is presented suggesting two separate processes are determining the success of precipitating uniform particles: generating and maintaining a stable suspension throughout the reaction and a self sharpening growth mechanism to provide narrow size distribution. Factors that control particle morphology in the absence and presence of shear and the mechanisms of growth of colloidally stable suspensions are discussed. Two factors are identified which control colloidal stability and precipitate morphology during precipitation: interaction potentials of the precipitates and the nature of depositing species. A short range repulsive force is found to be required to explain the particles colloidal behavior. Under certain conditions, a solvation minimum develops in the pair potential which acts to localize particles at small separations. Under these conditions agglomeration occurs during the reaction.
HCl and NaCl are added to the precipitating system to alter precipitate surface charges and solution ionic strengths, and the resulting morphologies are discussed. Comparison of experimental results and model predictions is made for the effect of HCl and NaCl on the particle morphology with thermal motion in the absence of shear and with shear in the absence of thermal motion.
Issue Date:1991
Rights Information:Copyright 1991 Look, Jee-Loon
Date Available in IDEALS:2011-05-07
Identifier in Online Catalog:AAI9136667
OCLC Identifier:(UMI)AAI9136667

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