CO2 Retention in High-Alkali Borate Glasses

A study of the high-alkali region of glass formation in the system Na₂O +B₂O₃ reveals that retention of CO₂ from carbonate starting materials can become a serious preparative problem at the high-alkali extreme. Results presented for glasses prepared using both Na₂O and Na₂CO₃ show that residual CO₂ can lead to major differences in physical properties which in this work are represented by the viscosity-related glass transition temperature .