Thermal and X-ray measurements on n-hexatriacontane (C₃₆H₇₄)

Abstract

Abstract. The polymorphism of n-hexatriacontane (C3JI74) was investigated by X-ray diffraction and DSC thermal analysis. C3JI74 displays at least two stable monoclinic phases and a rotator phase. Starting from a solution-grown sample of very high purity the following phases are observed with increasing temperature : MOI 1 < 345K < M101 < 346K < RIII < 348K < liquid. Depending on the thermal treatment also other forms may be observed. During these transitions, both the crystalline volume and the lamellar thickness increase. The higher order reflections of the layer structure was precisely measured by X-ray diffraction. Using a Fourier synthesis, electron density profiles of the three phases were analysed. The results show that the interlamellar structure is disturbed by increasing molecular motions with elevating températures. For some homologous alkanes also p (T) phase diagrams and binary systems have been studied.

Effects of several inter-molecular interactions on the inclusion between methyl substituted β-cyclodextrin and some linear macromolecule in supercritical carbon dioxide medium

“…4). In the DSC gram, a couple of peak was observed at 74-76°C due to the melting of free HTC in the product [37,38]. After treated in scCO 2 medium, the heat for the melting of free HTC in per gram sample was evidently decreased ( Table 4).…”