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Light scattering study on sol-gel transformation of SiO2 colloid at extremely high concentrations

TitleLight scattering study on sol-gel transformation of SiO2 colloid at extremely high concentrations
Publication TypeJournal Article
Year of Publication1998
AuthorsXu, YN, Koga, Y
JournalClays and Clay Minerals
Volume46
Pagination161-166
Date PublishedApr
Type of ArticleArticle
ISBN Number0009-8604
KeywordsAGGREGATION, DENSITY FLUCTUATION, GLASS, GROWTH, light scattering study, PARTICLES, SILICA, SiO2 colloids, sol-gel transformation, TRANSITION, X-RAY-SCATTERING
Abstract

Ludox SiO(2 )sols with a reasonably uniform size of 12 nm and in the high concentration of 10 to 40 wt% were transformed to gels by lowering the pH. The process from sol to gel, followed by light scattering, did not show a sign of fractal growth within the length scale of observation (>40 nm). Rather, a density fluctuation due to a dynamic (non-equilibrium) disorder was apparent. Together with the results of viscosity measurements, it was concluded that the process consists of 3 stages: 1) A dynamic (non-equilibrium) density fluctuation grows rapidly. 2) Such density fluctuation acquires some order. 3) The entire bulk loses fluidity and becomes a macroscopic gel.

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