X-ray diffraction and microcalorimetry study of the α→β transformation of tripalmitin

doi:10.1016/0040-6031(95)02742-4

Thermochimica Acta

Volume 276, 25 April 1996, Pages 229-242

https://doi.org/10.1016/0040-6031(95)02742-4 Get rights and content

Abstract

The polymorphic α→β transformation of tripalmitin was studied using two independent methods-thermodiffractometry and microcalorimetry-in the temperature range from 25.0 to 42.5°C. DSC was used as a preliminary tool to interpret the transformation process. In the DSC-scan the transition consisted of one endothermic and two exothermic peaks, one after the other, but in the isothermal microcalorimeter measurement the transition was a resultant of these three processes. The average reaction enthalpy was −45.6J/g and −47.0J/g by microcalorimetry and DSC, respectively. The concentration versus time curve of β-state during the α→β transformation was fitted using the Avrami equation. The activation energy associated with the transformation was 410 kJ/mol as measured by thermodiffractometer and 455 kJ/mol by microcalorimeter. The uniformity of the results proved that these methods were reliable tools in the study of this thermally activated process.

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The formation of the various polymorphs depends upon the crystallisation conditions. A number of studies have employed x-ray diffraction (XRD) methods to investigate the formation of polymorphism of tripalmitin (Sato and Kuroda, 1987; Kellens et al., 1990a, b; Hongisto et al., 1996). XRD is a popular tool for the study of TAG polymorphism as characteristic diffraction patterns can be identified for the different packing of each polymorph.
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Regular paperX-ray diffraction and microcalorimetry study of the α→β transformation of tripalmitin

Abstract

J. Pharm. Sci.

Int. J. Pharm.

Int. J. Pharm.

J. Am. Chem. Soc.

J. Am. Oil Chem. Soc.

J. Am. Oil Chem. Soc.

Acta Chem. Scand.

Regular paper
X-ray diffraction and microcalorimetry study of the α→β transformation of tripalmitin