モノグリセリドの多形 (第7報) : 結晶成長における溶媒効果

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Correlation between crystal habit and the modification of crystals by growth conditions was examined by electron microscope, polarization microscope, and X-ray diffraction, using a single crystal obtained from 1-monostearin by a solution method.<BR>1) The crystal growth from ethyl alcohol solution gave a single crystal of leaf-like pattern, the growth form was not uniform, and the steps on the crystal surface were irregular (Fig.-1). Crystal growth from benzene and carbon tetrachloride solutions gave a lamellar single crystal, forming polyhedral or rhombic crystals by the growth in a definite direction, and the crystal surface showed a two-dimensional growth in the direction of a and b axes and a pattern formed through a screw dislocation (Fig.-2, 3). Consequently, mechanism of the crystal growth of 1-monostearin can be explained by both the theories of growth by the formation of a two-dimensional nucleus and that by screw dislocation.<BR>2) The long spacings of the single crystals grown from ethyl alcohol, benzene, and carbon tetrachloride solutions agree with the β-type long spacing of 1-monostearine. Therefore, the morphology of a single crystal is affected by the kind of solvent used, its concentration, and temperature of crystal growth, but these conditions have no effect on crystal modification.