Viscosity effect on the structural compactness of latex flocs formed under weak depletion attractions

Yan, Y. D., Burns, J. L., Jameson, G. J. and Biggs, S. (2002) Viscosity effect on the structural compactness of latex flocs formed under weak depletion attractions. Journal of Colloid and Interface Science, 255 1: 91-97. doi:10.1006/jcis.2002.8636


Author Yan, Y. D.
Burns, J. L.
Jameson, G. J.
Biggs, S.
Title Viscosity effect on the structural compactness of latex flocs formed under weak depletion attractions
Journal name Journal of Colloid and Interface Science   Check publisher's open access policy
ISSN 0021-9797
1095-7103
Publication date 2002-11-01
Year available 2002
Sub-type Article (original research)
DOI 10.1006/jcis.2002.8636
Open Access Status Not yet assessed
Volume 255
Issue 1
Start page 91
End page 97
Total pages 7
Place of publication Maryland Heights, MO, United States
Publisher Academic Press
Language eng
Abstract Dilute aqueous dispersions of colloidal polystyrene latex spheres were flocculated by adding a nonadsorbing polymer sample, poly(acrylic acid). The structural compactness of the flocs thus formed was characterized in terms of their mass fractal dimension using the small-angle static light scattering technique. It was found that with low poly(acrylic acid) concentrations and thus weak depletion attraction forces, the dispersion medium viscosity had a marked effect on the floc structure. An increase in the viscosity led to formation of denser flocs. This was revealed in three sets of depletion flocculation experiments: (a) adjusting the background electrolyte concentration at a fixed level of poly(acrylic acid), (b) using water and 30% (w/w) glycerol as the respective solvents, and (c) inducing latex flocculation with two poly(acrylic acids) of different molecular weights at the respective critical polyacid concentrations. Direct force measurements were made with atomic force microscopy to isolate the influence of viscosity on floc structure from that of interparticle interaction energies. We conclude that the formation of denser flocs with increasing medium viscosity can be attributed to the reduced diffusivity of particles in the solution. The latter resulted in an enhanced rate of floc restructuring (through relaxation of attached particles) relative to floc growth.
Keyword Colloids
Depletion flocculation
Force measurement
Fractal aggregates
Static light scattering
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Non-UQ

Document type: Journal Article
Sub-type: Article (original research)
Collection: School of Engineering Publications
 
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