Bioactive glasses with improved processing. Part 2. Viscosity and fibre drawing

Bioactive glasses, particularly Bioglass® 45S5, have been used to clinically regenerate human bone since the mid-1980s; however, their high crystallisation tendency still limits their range of applications. It has been previously shown that by increasing the calcium/alkali ratio compared to 45S5 while also partially substituting potassium oxide for sodium oxide, the crystallisation tendency can be reduced while the ability of the glass to form apatite in physiological solutions is maintained. Here, the viscosity behaviour of these glasses is investigated and shows that these compositional changes also result in a less fragile behaviour of the glass melt, compared to 45S5. 45S5 crystallises in the temperature range corresponding to viscosities suitable for fibre drawing, while the reduced crystallisation tendency of the new glasses allowed for the drawing of fibres from a preform.