Kinetics of melt crystallization and transformation of tripalmitin polymorphs

The rates of melt crystallization and phase transformation of three polymorphs of tripalmitin were examined by optical microscopy, X‐ray diffractometry and DSC with and without surfactant additives (sorbitan mono‐ and tristearates). The following results were obtained: (a) Crystallization rate increased in order ofα, β′ andβ; (b) transformation rate was slower than crystallization rate for each polymorph at the same temperature examined; (c) when the most stableβ form was recrystallized from the melt just after the melting ofα, its recrystallization rate was much higher than that by simple melt‐cooling; (d) surfactant additives retarded both the crystallization and transformation of all the polymorphs, yetβ′ was influenced the most. A mechanistic interpretation based on the molecular structures both of the melt and of each polymorph is presented.