Glass transition temperature of glasses in the SiO2-Na2O-CaO-P2O5-Al2O3-B2O3 system
A total of 24 glasses in or near the bioactive region in the system SiO2-Na2O-CaO-P2O5-Al2O3-B2O3 were studied. By differential thermal analysis their glass transition temperatures,Tg, were determined. On basis of an experimental plan for 16 glasses, two phenomenological equations describing the relationship betweenTg and glass composition were developed. The equations describeTg within the compositional ranges: SiO2, 38.0–65.5 Na2O, 15.0–30.0; CaO, 10.0–25.0; P2O5, 0–8.0; B2O3, 0–3.0; Al2O3, 0–3.0 wt%. The glass transition temperature shows a linear dependence of the Na2O content. The higher the Na2O content, the lower theTg. Compositional alterations not including Na2O influencesTg little in comparison with changes in the Na2O content.
KeywordsPolymer SiO2 Al2O3 Transition Temperature Thermal Analysis
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