%0 Journal Article %T Phase diagram ofn-hexacosane andn-octacosane: experimental determination and calculation %+ GREENER %+ Laboratoire Réactions et Génie des Procédés (LRGP) %+ IFP Energies nouvelles (IFPEN) %A Provost, Élise %A Balesdent, Daniel %A Bouroukba, Mohammed %A Petitjean, Dominique %A Dirand, Michel %A Ruffier-Meray, Véronique %< avec comité de lecture %@ 0021-9614 %J Journal of Chemical Thermodynamics %I Elsevier %V 31 %N 9 %P 1135 %8 1999-09 %D 1999 %R 10.1006/jcht.1999.0526 %Z Engineering Sciences [physics]/Chemical and Process EngineeringJournal articles %X The phase diagram of (n-octacosane + n-hexacosane) has been determined experimentally, using a crystallographic and a calorimetric method, in the n-octacosane mole fraction range x = (0.2 to 0.7). In this composition range, the mixtures show an intermediate solid solution at room temperature, denoted beta ", with an orthorhombic structure, identical to the one found in other binary, or ternary systems, and in crude oil. With increasing temperature, this solid solution undergoes two solid-solid transitions, leading to another orthorhombic phase, denoted beta(Fmmm), then to a rhombohedral "Rotator" phase, denoted alpha-RII, before melting. The phase diagram has been calculated by using the following assumptions: ideality of the liquid phase mixture, ideality of the alpha-RII rotator phase mixture, and non-ideality of the mixture in the beta, and beta " phases whose excess Gibbs energies are represented by Margules equations (one- and two-parameter, respectively). The enthalpies of transformation, the temperatures of transformation, and the heat capacities of the pure compounds have been either measured, or extrapolated from the mixtures values. This allows a good representation of the phase diagram through the use of simple expressions. %G English %L hal-01185588 %U https://hal-ensta-paris.archives-ouvertes.fr/hal-01185588 %~ ENSTA %~ IFP %~ CNRS %~ UNIV-LORRAINE %~ LRGP-UL %~ LRGP-CITHERE