RELATIONSHIP BETWEEN MOLECULAR WATER AND HYDROXYL-GROUPS IN RHYOLITICAND QUARTZ GLASSES

The relationship of the speciation of water in glasses, which depends on total dissolved water and on composition of the grass, is a problem of great interest. Glasses with different contents of water in the rh yolite-water and SiO2-2.9 wt% H2O systems were synthesized in this inv estigation. In quartz glass, NMR spectroscopy was used to determine th e presence of OH groups only. Calorimetric determinations of the entha lpy of water dissolution in rhyolite and quartz glasses were performed . The thermal effect of the formation of OH groups at dissolution in q uartz glass is almost three times higher than in the alumosilicate gla ss. This indicates that different reactions take place in these system s with the formation of OH groups during water dissolution.