Due to the complexity of the chemical and molecular composition of oil, it is usually used to identify four main components: asphaltenes, resins, paraffins and oils. According to the accepted methods of GOST 11851085, M 01-12-81 paraffins are extracted not directly from oil as, for example, asphaltenes, but from pre-separated oils. In this study, results of research by NMR of benzene and alcohol-benzene resins extracted from oil according to the standardized procedure of GOST 11858-66 were carried out. It was found that benzene resins show hysteresis in NMR characteristics that is typical of systems with the first order phase transition, while alcoholtobenzene resins show no hysteresis over the temperature range from minus 80 to plus 65 degrees Celsius accurate to the experimental error. It has been suggested that as a result of peculiarities of interaction between resins and paraffins, the paraffins are extracted from oil mainly in the composition of benzene resins.
61.18.Fs Magnetic resonance techniques; Mossbauer spectroscopy
61.66.-f Structure of specific crystalline solids
65.60.+a Thermal properties of amorphous solids and glasses: heat capacity, thermal expansion, etc.
$^1$1Kazan (Volga Region) Federal University, Institute of Physics, Department of Molecular Systems Physics.