Please use this identifier to cite or link to this item: https://doi.org/10.1016/j.powtec.2007.11.047
Title: Yield stress-zeta potential relationship of oxide dispersions with adsorbed polyacrylate - Steric effect and zeta potential at the flocculated-dispersed transition state
Authors: Ong, B.C.
Leong, Y.K.
Chen, S.B. 
Keywords: Alumina
Coated titania
Critical zeta potential
Flocculated-dispersed transition state
Polyacrylate
Yield stress-DLVO relationship
Issue Date: 11-Aug-2008
Citation: Ong, B.C., Leong, Y.K., Chen, S.B. (2008-08-11). Yield stress-zeta potential relationship of oxide dispersions with adsorbed polyacrylate - Steric effect and zeta potential at the flocculated-dispersed transition state. Powder Technology 186 (2) : 176-183. ScholarBank@NUS Repository. https://doi.org/10.1016/j.powtec.2007.11.047
Abstract: The yield stress-DLVO force relationship is obeyed by α-Al2O3 and alumina-coated TiO2 dispersions with adsorbed polyacrylate only if the yield stress and its corresponding zeta potential data were collected in the positively charged region. In this region, the underlying surface positive charge density of the particles exceeds the negative charge density of the polyacrylate. At this state the adsorbed polyelectrolyte lies flat on the particle surface forming a steric layer of fixed thickness at a given polymer concentration. In the negative charge region, the steric layer thickness is not constant and hence yield stress-DLVO relationship is not obeyed. The (critical) zeta potential at the flocculated-dispersed transition state decreases with increasing polymer concentration. This result reflects a decreasing van der Waals force as the steric layer increases in thickness. A steric layer ensured that the surface or zeta potential is sufficiently low in the flocculated regime for the DLVO theory to remain valid. The ratio of the critical zeta potential square between alumina-coated TiO2 and α-Al2O3 is an indication of their Hamaker constants ratio in water. The effect of alumina coating on the value of this ratio is presented and discussed. © 2007 Elsevier B.V. All rights reserved.
Source Title: Powder Technology
URI: http://scholarbank.nus.edu.sg/handle/10635/90502
ISSN: 00325910
DOI: 10.1016/j.powtec.2007.11.047
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