Abstract:
A precision study of the phase transformation process during heating of n-alkanes: triacontane C$_{30}$H$_{62}$, dotriacontane C$_{32}$H$_{66}$ and hexatriacontane C$_{36}$H$_{74}$ was carried out using the differential scanning calorimetry method. Phase transformations in the solid state were considered from the point of view of the theory of diffuse phase transitions, which made it possible to distinguish three individual stages in the processes of transition development based on the analysis of the shape of heat capacity peaks and to conduct their independent analysis. A single mechanism of structural transformations from the initial monoclinic modification to the rotator phase through intermediate orthorhombic and monoclinic phases was established for the considered n-alkanes homologues. Each of the phase transformations was characterized in the approximation of heterogeneous development of the phase transition. The critical length of the n-alkane chain required for the implementation of the solid-solid phase transition was established.
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