Mise au point sur le comportement énergétique et cristallographique des n-alcanes

New insights on the crystalline forms in binary systems of n-alkanes: Characterization of the solid ordered phases in the phase diagram tricosane + pentacosane

“…1,2,39,45 Therefore, the derivation of atomic coordinates for any other member could be easily derived from the fractional coordinates of the carbon atoms C (1) and C (2) of the alkane C 23 . 49 We have therefore derived the fractional coordinates of C 25 in the O i form and obtained the list of reflections with their intensities.…”

“…C (1) 0.014 0.186 0.0239 0.90 C (2) 0.092 0.314 0.0435 1.00 C (3) 0.014 0.186 0.0631 1.00 C (4) 0.092 0.314 0.0827 1.00 C (5) 0.014 0.186 0.1023 1.00 C (6) 0.092 0.314 0.1219 1.00 C (7) 0.014 0.186 0.1415 1.00 C (8) 0.092 0.314 0.1611 1.00 C (9) 0.014 0.186 0.1807 1.00 C (10) 0.092 0.314 0.2003 1.00 C (11) 0.014 0.186 0.2199 1.00 C (12) 0.092 0.314 0.2395 1.00 C (13) 0.014 0.186 0.2591 1.00 C (14) 0.092 0.314 0.2788 1.00 C (15) 0.014 0.186 0.2987 1.00 C (16) 0.092 0.314 0.314 1.00 C (17) 0.014 0.186 0.3376 1.00 C (18) 0.092 0.314 0.314 1.00 C (19) 0.014 0.186 0.3770 1.00 C (20) 0.092 0.314 0.3964 1.00 C (21) 0.014 0.186 0.4160 1.00 C (22) 0.092 0.314 0.4356 1.00 C (23) 0.014 0.186 0.4552 1.00 C (24) 0 and binary mixed samples do not change significantly with chain length), and z͞c coordinates were obtained by extrapolation along the z-axis of the chain model used by Dorset. 51 The fractional atomic occupancies (see Table I) which are applied to the chain ends have no effect on the angular position of the diffraction lines if not on the intensities and specially those of the 00l lines.…”

“…Five rotator forms are known to exist, 19,20 denoted R I , R II , R III , R IV , and R V , and are observed until C 39 H 80 . In the range 8 < n < 28, Roblès et al 1,22 and Espeau et al 2 give the complete phase transitions in these alkanes incorporating the rotator forms. Odd alkanes always show at least one rotator phase before melting.…”

Protection of temperature sensitive biomedical products using molecular alloys as phase change material

“…Five pure n-alkanes were chosen with a melting temperature adapted to the desired temperature range: C 12 , C 13 , C 14 , C 15 and C 16 (C n denoted a n-alkane with n carbon atoms in the chain). From a fundamental point of view, the polymorphism of the n-alkanes in this range of n were previously determined [4]. But pure n-alkanes are not the cheapest solutions.…”

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

“…For these applications the study of binary or multi-°l M012 101 Rm components systems of n-alkanes is partic-3 ularly interesting [2][3][4]. \ M201 Mlol Ra The polymorphism observed in n-alkanes (b) ffi has been reviewed in detail [5][6][7][8]. Various low-temperature modificatîons and disordered rotator phases have been found.…”