Rheology and colloidal structure of aqueous TiO2 nanoparticle suspensions
Rheological behavior and suspension structure of anatase titanium dioxide (TiO2) nanoparticles dispersed in pure water have been investigated over a range of volumetric solids concentrations (*q =0.05-0.12) and shear rates (*g=101-103 s-l). The nanoparticle suspensions generally exhibited a pseudopl...
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Veröffentlicht in: | Materials science & engineering. A, Structural materials : properties, microstructure and processing Structural materials : properties, microstructure and processing, 2003-08, Vol.355 (1-2), p.186-192 |
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Sprache: | eng |
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Zusammenfassung: | Rheological behavior and suspension structure of anatase titanium dioxide (TiO2) nanoparticles dispersed in pure water have been investigated over a range of volumetric solids concentrations (*q =0.05-0.12) and shear rates (*g=101-103 s-l). The nanoparticle suspensions generally exhibited a pseudoplastic flow behavior, indicating an existence of particle aggregations in the liquid medium. The suspensions became apparently thixotropic as *q was increased above 0.1. Relative viscosity (*hr) of the suspensions followed an exponential form with *q, i.e., *hr = 13.47e35.98*q, revealing a pronounced increase in the degree of particle interactions as *q increased. Fractal dimension (Df) was estimated from the suspension yield-stress (ry) and *q dependence, and was determined as Df#~1.46-1.78 for the flocculated nanoparticle suspensions. This suggested that the suspension structure was probably dominated by the diffusion-limited cluster-cluster aggregation, due mostly to the strong attractions involved in the interparticle potentials. Maximum solids loading (*qm) of the suspensions was determined as *qm= 0.146. This relatively low value of *qm (compared with the random close packing of monosized particles, *qm #~ 0.64) partially vindicated the existence of a porous, three-dimensional aggregate network of interconnected nanoparticles in the carrier liquid. |
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ISSN: | 0921-5093 1873-4936 |
DOI: | 10.1016/S0921-5093(03)00063-7 |