Structural, thermal and dissolution properties of MgO- and CaO-containing borophosphate glasses: effect of FeO addition

This paper investigated manufacture of high-durability phosphate glass fibres for biomedical applications. Five different borophosphate glass formulations in the systems of 45PO–5BO–5NaO–(29 − x)CaO–16MgO–(x)FeO and 45PO–5BO–5NaO–24CaO–(21 − x)MgO–(x)FeO where x = 5, 8 and 11 mol% were produced via melt quenching. The compositions and amorphous nature of the glasses were confirmed by ICP-MS and XRD, respectively. FTIR results indicated depolymerisation of the phosphate chains with a decrease in Q units with increasing FeO content. DSC analyses showed an increase in T by ~5 °C with an increment of 3 mol% in FeO content. The thermal properties were also used to calculate processing window (i.e. T—T) and another parameter, K, to determine the suitability for fibre drawing directly from melt, which equals (T—T)/(T—T). The degradation study conducted in PBS solution at 37 °C showed a decrease of 25–47% in degradation rate with increasing FeO content. This confirmed that the chemical durability of the glasses had increased, which was suggested to be due to FeO addition. Furthermore, the density measured via Archimedes method revealed a linear increase with increasing FeO content.