Crystallization in stone wool fibres

The crystallization behavior of stone wool fibres (SWFs) is studied by isothermally heat-treating the SWFs under atmospheric conditions, and by determining the crystallization enthalpy (ΔHht) released from the samples during heat-treament. The dependences of the degree of crystallization (Dc) on the heat-treatment temperature (Th) and time (th) are clarified using differential scanning calorimetry (DSC), X-ray diffraction (XRD), and electron scanning microscopy (SEM). These dependences can be well described by a phenomenological model proposed in this work. The morphology of the crystals is analyzed using SEM, whereas the structure of the crystals and the maximum fraction of crystalline phase in the SWFs are determined using XRD. From a direct comparison between the XRD and DSC data, it is found that the Th and th dependences of ΔHht overlap with those of Dc. This overlapping leads to the possibility of predicting Dc(Th, th) for the SWFs from the heat-treatment conditions using the above-mentioned model.