| Project/Area Number |
07651017
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
無機工業化学
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| Research Institution | The University of Shiga Prefecture |
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Principal Investigator |
MATSUOKA Jun The University of Shiga Prefecture, School of Engineering, Assistant Professor, 工学部, 講師 (20238984)
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| Co-Investigator(Kenkyū-buntansha) |
YOSHIDA Statoshi The University of Shiga Prefecture, School of Engineering, Research Associate, 工学部, 助手 (20275168)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥1,900,000 (Direct Cost: ¥1,900,000)
Fiscal Year 1996: ¥200,000 (Direct Cost: ¥200,000)
Fiscal Year 1995: ¥1,700,000 (Direct Cost: ¥1,700,000)
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| Keywords | Sol-gel reaction / Silicon alkoxides / tetraethyl orthsilicate / heat of reaction / hydrolysis / condensation / exothermic reaction / cluster / ゾル-ゲル法 / シリカガラス / 生成エンタルピー / 粘性 / 紫外反射率 / 真空紫外反射率 / アルコキシド |
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| Research Abstract |
In order to investigate the nature of hydrolysis-condensation process in sol-gel reaction, heat of reaction of some silicon alkoxides, such as tetraethyl orthosilicate and its derivative in which some of the ethoxy groups were substituted to methyl groups, were measured. Results are as follows :
In the hydrolysis-condensation process of tetraethyl orthosilicate, hydrolysis is a large exothermic process. On the other hand, heat of reaction at the condensation process is very small. This small value for condensation process has been known for aqueous systems since about fifty years ago, and is also found for alcoholic systems in this study.
In the case of tetraethyl orthosilicate, rate of exothermic reaction is proportional to the 1.5th power of the acid concentration, and that for methyl triethoxysilane is 1.3. The reason that the exponent is fractional should be the fact that the reaction is actually the multi-step ones.
At high concentration of catalyst, the rate of exothermic hydrolysis reaction becomes constant and does not depend on the catalyst concentration at the initial stage of reaction. This may be due to the fact that diffusion of alkoxids limits the overall reaction. On the other hand, at low concentration of catalyst, some elementally reaction will limits the overall reaction.
The rate of exothermic reaction at the initial stage in the system of tetraethyl orthosilicate is proportional to the 0.24th power of water concentration. This should be due to the fact that water molecules make cluster structure in alcoholic solution.
In addition to the thermodynamic study, vacuum ultraviolet reflection spectra were investigated for oxide gels and for silica glass. gels were found to have a different structure with the glass.
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