Following bioactive glass behavior beyond melting temperature by thermal and optical methods

The thermal behavior of a well known bioactive glass, Bioglass®, is examined beyond its melting temperature as the crystallization and sintering of bioactive glass may influence its bioactivity and cellular reactions. Differential thermal analysis (DTA) followed by thermogravimetric analysis (TGA) was used to determine the glass transition (Tg), the crystallization (Tc), the melting (Tm) temperatures and the weight changes. The characterization of bioactive glass before and after the thermal treatment at different characteristic temperatures was accomplished with Fourier transform infrared spectroscopy (FTIR). All the phases, during the heating of the material until an exact temperature beyond its melting temperature were determined. A progressive increase of its crystallization degree was observed, during treatment up to 1200 °C. At this temperature a number of successive crystallizations and fusions take place. At higher temperatures the formation of amorphous Bioglass® with simultaneous appearance of new phases is observed, favouring the bioactivity that in glass-ceramics is influenced by the different phases present. (© 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)