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Rheological properties of aqueous α A1 2 O 3 suspensions: Influence of dispersant concentration
Author(s) -
Zupančič Andreja,
Lapasin Romano,
Kristoffersson Annika
Publication year - 1999
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.5450770403
Subject(s) - dispersant , thixotropy , polyacrylic acid , rheology , viscoelasticity , polyelectrolyte , aqueous solution , materials science , saturation (graph theory) , chemical engineering , adsorption , chemistry , composite material , polymer , dispersion (optics) , organic chemistry , mathematics , physics , combinatorics , optics , engineering
The effects of concentration of polyacrylic acid as a dispersant on rheological properties of aqueous alumina suspensions have been investigated under steady and oscillatory shear conditions. At solid volume fractions between 0.45 and 0.6, a high degree of particle stabilization is achieved when 0.2 wt% of polyacrylic acid is added. At lower dispersant concentrations, suspensions exhibit pronounced irreversible thixotropic behaviour, whereas at higher dispersant concentrations, time dependent effects on the flow properties are not detectable. When the saturation adsorption limit of the polyelectrolyte on Al 2 O 3 is reached, further addition of the dispersant appreciably changes the flow behaviour, as well as the viscoelastic response of investigated suspensions. The data under steady shear are described by application of the generalized Casson model, and for the analysis of viscoelastic data the generalized Maxwell model is used.