Thermal Evolution of Hybrid Organic-Inorganic Gels Derived from Reaction of 1,4 Butanediol with Tetraethoxysilane |
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Authors: | Satish M. Manocha Deval Y. Vashistha L.M. Manocha |
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Affiliation: | (1) Department of Materials Science, Sardar Patel University, Vallabh Vidyanagar, 388120 Gujarat, India |
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Abstract: | Transparent monolithic discs of organic-inorganic hybrid gels have been prepared by hydrolysis-condensation reactions of tetraethyl orthosilicate with 1,4 butanediol. The gels and glasses have been characterized by infrared spectroscopy and 29Si MAS NMR. The characterization of the gels by infrared spectroscopy showed the incorporation of carbonaceous groups in the polymeric structure and Si–C bonding in the glasses. Pyrolysis of the gels has been studied using thermal analysis. It showed that the pyrolysis of the gels occurs in two temperature domains. The first is below 400°C due to condensation reactions and second is in the temperature range 450–550°C due to decomposition of carbonaceous groups and crosslinking. Pyrolysis of the gels at 1000°C resulted in X-ray amorphous, hard black glasses similar to oxycarbide glasses obtained by pyrolysis of siloxanes. On further heat treatment to 1400–1600°C, development of cristobalite structure and crystalline silicon carbide is observed in the otherwise amorphous black mass. The pyrolysed materials have been found to exhibit good resistance towards oxidation at 1000°C. |
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Keywords: | organic-inorganic hybrid gels hydrolysis pyrolysis sol-gel silicon oxycarbide silicon carbide |
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