Microwave curing of hybrid inorganic-organic ceramers and some additional structural features of these material

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Virginia Tech

This dissertation reflects the results of probably the very first attempt to cure sol gel ceramers using microwaves. These materials were first prepared in 1985, but were found to take almost two to six days to cure, when stored under ambient conditions. Microwaves have been found to provide a method for circumventing this problem under certain conditions. It was discovered that the more highly phase separated ceramer systems can be cured in twenty minutes when subjected to heating in a microwave field. Curing in a conventional oven, has on the other hand been found to hinder the extent of reaction because the slow initial rate of heating (which allows for evaporation of some of the compatibilizing solvent media) is believed to leave the reactants in a somewhat diffusion limited state.

Dielectric investigations on the ceramer films show the existance of Maxwell Wagner Sillars intefacial polarization which results from charge migration in the ceramer system and also show the possibility of PTMO chain expansion at higher metal alkoxide contents in these ceramers when cast onto a substrate onto which the film adheres. Finally, structural investigations into the ceramers using SAXS, gives an idea of the fractal dimensions of the scattering phases. These investigations have also proved quite conclusively that there exists a contribution to scattering from the porosity present in the inorganic phase at metal alkoxide contents as low as 40 wt%.