Modulated temperature differential scanning calorimetry for examination oftristearin polymorphism: 2. Isothermal crystallization of metastable forms

The transformations of tristearin were examined by modulated temperature di fferential scanning calorimetry (MTDSC) in order to examine the utility of this technique. Tristearin has been used as a model polymorphic system, sho wing metastable phases and complicated transformation routes occurring at r elatively slow rates. The beta'-forms generated by thermal treatment under modulation do not differ significantly from those generated by the correspo nding treatment without modulation. While the total heat flow thermograms a re similar, the deconvoluted reversing component shows that annealing, espe cially at 63 degrees C, has a significant effect on the crystal size and pe rfection of the solid phases formed. MTDSC also enables the melting of beta ' to be separated from the simultaneous crystallization of the beta form as evidenced in the c(p) component. Quantitative interpretations about such s ystems cannot be drawn from MTDSC at this point in time.