PHASE-TRANSFORMATIONS OF NORSULFAZOL DURING MECHANICAL ACTIVATION

The effect of mechanical treatment in a planetary ball mill on the tra nsformations of polymorphs of norsulfazol was studied by means of X-ra y diffraction analysis, infrared spectroscopy and differential scannin g calorimetry. It has been shown that mechanical treatment initiates m utual transitions of norsulfazol polymorphs III reversible I. In an in itial period of mechanical treatment a part of norsulfazol was convert ed into a noncrystalline solid, while long-term mechanical treatment g ave rise of substance recrystallisation. Preliminary mechanical treatm ent of form III resulted in the reduction of III --> I phase transitio n temperature by 20-30-degrees in the samples without high temperature form 1 and by 40-50-degrees in the samples where the part of substanc e were transformed into form 1 during mechanical treatment. Single cry stal thermomicroscopy studies showed that III --> I phase transition p roceeds via nucleation and a rapid advance of an interface through the crystal. The places of indentation were the centres of nucleation. It seems that deformation of crystals during mechanical treatment and fo rmation of noncrystalline solid with high extent of disordering make p robable the initiation of phase transition of norsulfazol during mecha nical treatment.