Moroz K. The influence of pressure on thermodynamic properties of polycyclic hydrocarbons

It is investigated the equation of state and molecular structure of molecular liquids. It is obtained the PVT data and the calculation of thermodynamic properties is performed for polycyclic hydrocarbons and for liquid systems containing fullerene С60 in the range of pressures from 0.1 to 245.2 MPa and in the range of temperatures from 313 К to 453 К. Substantiated analytic relations are suggested for the obtained thermodynamic properties. It is established that thermal expansivity and elastic modulus as a function of temperature on isochors reveal entropic character in all the investigated polycyclic hydrocarbons. It is carried out the search of semiempiric equation of state admitting statistic substantiation. The equation found has not only first but also second derivatives adequately representing the following thermobaric properties of molecular liquids: isobaric expansivity, elastic modulus, isothermal deviation of enthalpy, entropy, total internal energy, isobaric molar capacity, isochoric molarcapacity. It is carried out the calculation of molecular structure by using the method of probability density atom-atom distribution for polycyclic hydrocarbons: pinane, ?-pinene, 1-3-dimethyladamantane, 3-cyclopenthyltoluene, 3-cyclohexyltoluene, and fullerene С60 solution in toluene. It is shown by using the method of MD modelling that pressure amplifies orientational ordering in molecular liquids with anisotropic form of molecules, and the admixtures with spherical form of molecules weaken orientational ordering in the whole investigated range of pressures and temperatures.