Glasses hydrolytic classes

The following examples describe the extraction of alkali by water from 2 g samples at 97 3°C for three glasses of different hydrolytic class. 

Hydrolytic class Acid consumption of 0.01 mol/1 hydrolytic acid per g glass grains (ml/g) Base equivalent as Na2<) per g glass grains (Fg/S) Possible designation... 

Silica-based materials obtained by the sol-gel process are perhaps the most promising class of functional materials capable to meet such a grand objective. In the sol-gel process liquid precursors such as silicon alkoxides are mixed and transformed into silica via hydrolytic polycondensation at room temperature. Called soft chemitry or chimie douce, this approach to the synthesis of glasses at room temperature and pressure and in biocompatible conditions (water, neutral pH) has been pioneered by Livage and Rouxel in the 1970s, and further developed by Sanchez, Avnir, Brinker and Ozin. 

The Ph. Eur. classifies glass by hydrolytic resistance the resistance against attack by hydrolysis [17], Hydrolytic resistance is determined by steam sterilisation of the glass with water, followed by titration of the released OH -ions with acid. Based on the amount of OH -ions the Ph. Eur. classifies glass into three different classes ... 

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