水酸化リチウムで改質したシリカゾルの白濁固化現象

概要

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Silica sol is stable dispersions of discrete spherical silica particle in water, this particle has the size of 5-150nm. Various modified silica sols were prepared by adding lithium hydroxide to solica sol, and aging at 50℃. Authors studied on the white turbid and solidification phenomena of silica sols modified with lithium hydroxide during sols were heated, and changes of viscosity and pH of sol were also measured. Transparent or slight milk-white color of modified silica sol became white turbid at the temperature range of 55-95℃, and then solidified at almost the same temperature. This phenomena were observed at lower temperature in the sol with higher concentration of SiO_2, and observed at the lowest temperature in the sol with SiO_2/Li_2O molar ratio 4.5-5, and highest temperature in the sol with SiO_2/Li_2O molar ratio 3.5-4. Solidification phenomena were only observed in the sol with above the 10wt% of SiO_2. In the case of sol below SiO_2/Li_2O molar ratio of 4, the white turbid and solidification phenomena were mainly resulted by the crystallization of Li_2O・2SiO_2, and by gelation of ultra discrete spherical silica sol in the case above the ratio of 5.
1991-08-30