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Article: Characteristics of flocculated silica dispersions

TitleCharacteristics of flocculated silica dispersions
Authors
KeywordsColloids--Flocculation
Rheology--Calculations
Silica Gel--Rheology
Surface Active Agents--Grafting
Suspensions--Microstructure
Issue Date1991
PublisherAcademic Press. The Journal's web site is located at http://www.elsevier.com/locate/jcis
Citation
Journal of Colloid And Interface Science, 1991, v. 141 n. 2, p. 564-577 How to Cite?
AbstractInterparticle attractions manifest themselves in the rheology and microstructure of suspensions. One can investigate the effect of particle interactions in a flocculated dispersion by measuring the elasticity mechanically and determining the network dimensionality by static light scattering. For this purpose we synthesized a model system consisting of submicrometer silica spheres coated with octadecyl chains suspended in hexadecane. Lowering the temperature causes the silica-hexadecane system to form a gel network which possesses a measurable yield stress and elastic modulus. Rheological measurements at constant volume fraction reveal that the dispersion changes from fluid to solid within a narrow temperature range, defining a gel transition boundary. To quantify the magnitude of the attraction, we associate the gel transition with the percolation threshold for sticky spheres. At constant temperature, the elastic modulus increases with volume fraction following a power law. The power law exponent increases with increasing temperature, indicating a structural change in the gel network. We have probed the structure of these silica gels with static light scattering. The angular dependence of the scattering intensity differs significantly from that of a stable dispersion. The gel-liquid transition is observed over a 2°C range, substantiating the rheological results. At low temperatures, silica gels assume a fractal geometry with dimensionality of 2.08 ± 0.29. At high temperatures, the scattering intensity profile resembles that of primary particles, suggesting that interparticle attractions are significantly diminished. © 1991.
Persistent Identifierhttp://hdl.handle.net/10722/91416
ISSN
2015 Impact Factor: 3.782
2015 SCImago Journal Rankings: 1.126

 

DC FieldValueLanguage
dc.contributor.authorChen, Men_HK
dc.contributor.authorRussel, WBen_HK
dc.date.accessioned2010-09-17T10:18:58Z-
dc.date.available2010-09-17T10:18:58Z-
dc.date.issued1991en_HK
dc.identifier.citationJournal of Colloid And Interface Science, 1991, v. 141 n. 2, p. 564-577en_HK
dc.identifier.issn0021-9797en_HK
dc.identifier.urihttp://hdl.handle.net/10722/91416-
dc.description.abstractInterparticle attractions manifest themselves in the rheology and microstructure of suspensions. One can investigate the effect of particle interactions in a flocculated dispersion by measuring the elasticity mechanically and determining the network dimensionality by static light scattering. For this purpose we synthesized a model system consisting of submicrometer silica spheres coated with octadecyl chains suspended in hexadecane. Lowering the temperature causes the silica-hexadecane system to form a gel network which possesses a measurable yield stress and elastic modulus. Rheological measurements at constant volume fraction reveal that the dispersion changes from fluid to solid within a narrow temperature range, defining a gel transition boundary. To quantify the magnitude of the attraction, we associate the gel transition with the percolation threshold for sticky spheres. At constant temperature, the elastic modulus increases with volume fraction following a power law. The power law exponent increases with increasing temperature, indicating a structural change in the gel network. We have probed the structure of these silica gels with static light scattering. The angular dependence of the scattering intensity differs significantly from that of a stable dispersion. The gel-liquid transition is observed over a 2°C range, substantiating the rheological results. At low temperatures, silica gels assume a fractal geometry with dimensionality of 2.08 ± 0.29. At high temperatures, the scattering intensity profile resembles that of primary particles, suggesting that interparticle attractions are significantly diminished. © 1991.en_HK
dc.languageengen_HK
dc.publisherAcademic Press. The Journal's web site is located at http://www.elsevier.com/locate/jcisen_HK
dc.relation.ispartofJournal of Colloid And Interface Scienceen_HK
dc.subjectColloids--Flocculationen_HK
dc.subjectRheology--Calculationsen_HK
dc.subjectSilica Gel--Rheologyen_HK
dc.subjectSurface Active Agents--Graftingen_HK
dc.subjectSuspensions--Microstructureen_HK
dc.titleCharacteristics of flocculated silica dispersionsen_HK
dc.typeArticleen_HK
dc.identifier.emailChen, MZ:mzqchen@hku.hken_HK
dc.identifier.authorityChen, MZ=rp1317en_HK
dc.description.naturelink_to_subscribed_fulltext-
dc.identifier.scopuseid_2-s2.0-0026103434en_HK
dc.identifier.volume141en_HK
dc.identifier.issue2en_HK
dc.identifier.spage564en_HK
dc.identifier.epage577en_HK

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