Abstract
Intact and ground crystals of Sulfaguanidine (monohydrate) were prepared by recrystallization from aqueous solution with or without subsequent grinding. The hydrate was also prepared by sorbing H2O vapor on the particles of anhydrous sulfaguanidine. By using these as sample materials, the dehydration curves at various temperatures were determined under dry conditions at 1 atm and in vacuo, as well as under various conditions of humidity. The applicability of various kinetic equations for solid state decomposition was investigated. It was found that chemically the same hydrate was dehydrated through different mechanisms depending on the crystal properties of the samples and the environmental conditions. In addition, changes in surface appearance of the intact and the ground crystals were observed during heating at constant temperatures. It is suggested that the differences in the dehydration mechanisms may be attributable to different modes of nuclei growth.
