Thermal properties of 2-Oleodipalmitin and 2-Elaidodipalmitin and some of their mixtures

Abstract

The polymorphism of 2-oleodipalmitin (POP), 2-elaidodipalmitin (PEP), and five of their mixtures was investigated by differential scanning calorimetry (DSC). The heat of fusion (ΔH_f), heat of crystallization (ΔH_c), and heat of transition (ΔH_t) were determined. Rapid conversion to higher polymorphs, partial melting during conversion, and the overlapping of polymorphic forms precluded accurate determination of some caloric values. Four of five previously identified polymorphs of POP and all four polymorphs of PEP were identified by DSC. Five POP: PEP mixtures containing 8, 16, 25, 50, and 75% PEP, respectively, were examined. The presence of PEP in POP increased the stability of the lower POP polymorphs and, in concentrations as low as 8%, also increased the conversion rate of the higher POP polymorphs. In these heating curves, POP forms 5, 4, and 3, and a higher melting fraction that consisted of higher polymorphs of POP, polymorphs of PEP, and probably mixed crystals were evident. The ΔH_f values for the tempered mixtures are lower, and the ΔH_c values for the mixtures are higher than the calculated values. Heating and cooling curves and calorimetric data tables for POP, PEP, and their five mixtures are included.