New Interpretation of Heat Effects in Polymorphic Transitions
Journal of Thermal Analysis and Calorimetry
, E-ISSN: 1572-8943
||DSC Endo/exo Nucleation Polymorphism
Drebushchak Tatiana N.
Boldyreva Elena V.
Novosibirsk State University, Ul. Pirogova 2, 630090, Novosibirsk, Russia
Institute of Geology and Mineralogy SB RAS, Pr. Ac. Koptyuga 3, 630090 Novosibirsk, Russia
Institute of Solid State Chemistry and Mechanochemistry, SB RAS, ul. Kutateladze, 18, 630128 Novosibirsk, Russia
Overlapping endothermic and exothermic effects in DSC measurements of polymorphic transitions is often detected in molecular crystals and drugs. It is explained by the sequence of melting and crystallization. In this paper, we argue that this explanation is incorrect. In revealing the kinetic nature of the endo/exo thermal effect, we suggest another explanation, based on the nucleation. New interpretation does allow us to measure the energetic barrier in the nucleation of bulk sample, thus providing a tool for testing the nucleation models.