PHASE-TRANSITION STUDIES IN N-ALKANES AND PETROLEUM-RELATED WAXES - A REVIEW

A review is presented concerning the application of various analytical methods, viz. differential thermal analysis (DTA), differential scanning calorimetry (DSC), dilatometry, infrared spectroscopy, X-ray diffractometry, nuclear magnetic resonance spectrometry, electron diffraction and scanning tunneling microscopy for the investigation of solid-solid phase transition phenomenon in pure n-alkanes, their binary mixtures and petroleum (both paraffinic and microcrystalline) and related waxes. Particular attention has been paid to the phase transition mechanisms that can be revealed by different methods involving changes in complex molecular motions with temperature in petroleum waxes with emphasis on the similarities and deviations from n-alkanes. Pressure-induced phase-transitions are also discussed. Some of the possible future applications of this study have been outlined.