CRYSTALLIZATION BEHAVIOR OF HYDROGENATED SUNFLOWER-SEED OIL - KINETICS AND POLYMORPHISM

Kinetics of crystallization of hydrogenated sunflowerseed oil was stud ied by means of an optical method. Two different aspects were examined : the effects of preheating of the molten liquid on induction time of isothermal crystallization and the effects of cooling rate on the crys tallization behavior. Induction time for crystallization was markedly dependent on the crystallization temperature and the cooling rate sele cted. Morphology, polymorphism and chemical composition of the crystal s were examined. At all crystallization temperatures, beta'-form was f ound for the first occurring crystals. Long spacings were also similar in all cases and corresponded to a double chainlength arrangement. Th e chemical composition of the crystals showed no differences at either cooling rate. However, the melting behavior was different. At a slow cooling rate, fractionation occurred, and differential scanning calori metry diagrams had a broad second endotherm with three peaks, none of which were completely resolved. The polymorphic transformation rate fr om beta' to beta was slower when induction times were longer.