Shear-induced restructuring of concentrated colloidal silica gels

H J M Hanley; C D Muzny; B D Butler; G C Straty; John R Bartlett; E Drabarek

doi:10.1088/0953-8984/11/6/003

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Shear-induced restructuring of concentrated colloidal silica gels

Journal article

Peer reviewed

Shear-induced restructuring of concentrated colloidal silica gels

H J M Hanley, C D Muzny, B D Butler, G C Straty, John R Bartlett and E Drabarek

Journal of Physics: Condensed Matter, Vol.11(6), pp.1369-1380

1999

DOI: https://doi.org/10.1088/0953-8984/11/6/003

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Abstract

Condensed Matter Physics

Materials Engineering

Nanotechnology

The viscometric properties and structure of concentrated sheared colloidal gels, formed at a pH = 8 from a commercial aqueous sol of 7 nm diameter silica particles, were investigated. As the system gels under a constant shear rate, the viscosity first increases, then peaks when the shear stress reaches a shear-rate-independent threshold value of about 350 Pa, and finally decreases asymptotically to approximately one tenth the peak value. This low-viscosity state can apparently be held indefinitely by maintaining the shear, but the system gels once the shear is removed. The structural origins of this viscometric behaviour were studied using in situ small-angle neutron scattering (SANS). An abrupt change in the character of the SANS intensity was observed at the time corresponding to the peak in the viscosity. Samples of the gelling system were extracted and diluted at various times after gel initiation. Effective hydrodynamic diameters of these extractants were estimated by dynamic light scattering, and their Guinier diameters were estimated by SANS when appropriate. We conclude that the drop in viscosity corresponds to a structural densification of growing clusters of the colloidal particles, and that this transformation occurs once the critical stress is reached.

Details

Title: Shear-induced restructuring of concentrated colloidal silica gels
Authors: H J M Hanley (Author) - Australian Nuclear Science and Technology Organisation Materials Division
C D Muzny (Author) - National Institute of Standards and Technology, United States
B D Butler (Author) - National Institute of Standards and Technology, United States
G C Straty (Author) - National Institute of Standards and Technology, United States
John R Bartlett (Author) - Australian Nuclear Science and Technology Organisation Materials Division
E Drabarek (Author) - Australian Nuclear Science and Technology Organisation Materials Division
Publication details: Journal of Physics: Condensed Matter, Vol.11(6), pp.1369-1380
Publisher: Institute of Physics Publishing Ltd.
Date published: 1999
DOI: 10.1088/0953-8984/11/6/003
ISSN: 0953-8984
Organisation Unit: School of Science and Engineering - Legacy; University of the Sunshine Coast, Queensland
Language: English
Record Identifier: 99448798702621
Output Type: Journal article

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Web Of Science research areas: Physics, Condensed Matter

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