Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.13/33885

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Title
The effect of molecular weight of nonadsorbing polymer on the structure of depletion-induced flocs
Author/Creator
Burns, Janine L.;  Yan, Yao-de;  Jameson, Graeme J.;  Biggs, Simon
Institution
The University of Newcastle. Faculty of Engineering & Built Environment, School of Engineering
Description
This work explores the structural compactness of depletion-induced particle flocs with respect to the molecular weight of nonadsorbing polymer flocculants. Small-angle static light scattering was used to monitor the structural characteristics of the flocs, which were formed by the addition of nonadsorbing poly(acrylic acids) to a stable colloidal polystyrene latex dispersion. It was found that the floc mass fractal dimension, considered to be a measure of structural compactness, was dependent upon both the molecular weight and the concentration of the polyacid. In particular, reducing the molecular weight of the polymer at a fixed polyacid concentration resulted in higher mass fractal dimensions, despite the highly polydisperse nature of the polymer samples. This structural behavior was attributed to the lower particle sticking efficiencies upon collision. This reduced sticking ability is the result of the shallowing in the secondary potential energy well with decreasing polymer chain length, which was directly supported by atomic force microscopy data. Our results suggest that the formation of a shallower attraction well with a lower molecular weight nonadsorbing polymer is the result of the insufficiency of the increased osmotic pressure to counter-balance the short-ranged nature of the depletion interaction.
Relation
Journal of Colloid and Interface Science Vol. 247, Issue 1, p. 24-32
Publisher Link
http://dx.doi.org/10.1006/jcis.2001.8115
Date
2002
Publisher
Academic Press Inc.
Keyword(s)
depletion–flocculation;  light scattering;  atomic force microscopy;  fractal dimension;  colloids
Resource Type
journal article
Identifier
http://hdl.handle.net/1959.13/33885
Identifier
ISSN:0021-9797
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Subject
"Journal of Colloid and Interface Science"
 
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