The effect of heating on the dissolution of alkaline earth silicate fibers in a simple amino acid solution and water.

In order to evaluate the effect of pre-heating on biosolubility and water-resistance of alkaline earth silicate (AES) fibers in MgO-SrO-SiO2 and MgO-CaO-SrO-SiO2 compositions, dissolution experiments of the heat-treated (from 110 degrees C to 1,260 degrees C) AES fibers have been carried out in a glycine solution and in distilled water at 40 degrees C for 50 h. The dissolution experiments show that the heat-treatment around 700 degrees C has made the AES fibers more soluble in the glycine solution. This is due to the phase separation of the AES fibers resulting from the heat-treatment. Probably, alkaline earth-rich glassy phases formed by the phase separation facilitate the dissolution of the heat-treated AES fibers in the glycine solution. The heat-treatment around 700 degrees C is possible to decrease the toxicity of the AES fibers further. Meanwhile, this heat-treatment around 700 degrees C has given little effect on the dissolution of the AES fibers in the distilled water. This indicates that the resistance of the AES fibers to water or humidity remains unaffected by the heat-treatment. The water-resistance is a very useful property for MMVFs. This study suggests that the heat-treatment around 700 degrees C is probably an useful treatment in order to enhance the total performance, biosolubility and water-resistance, of AES fibers.