Thermodynamics of n-alkane + dimethylsiloxane mixtures. Part 1.—Gas–liquid critical temperatures and pressures

Abstract

Gas–liquid critical temperatures T^c_m have been determined for four mixtures: (i) n-hexane + hexamethyldisiloxane, (ii) n-octane + hexamethyldisiloxane, (iii) n-octane + octamethyltrisiloxane, and (iv) n-octane + 2,2,4,4-tetramethylpentane. Using a statistical model based upon the van der Waals one-fluid approximation, values of T^c_m for each mixture are related to a parameter ζ which is proportional to the energy of interaction between the unlike molecular species. Gas–liquid critical pressures p^c_m are reported for mixtures (i), (ii) and (iii), and the results are discussed in terms of possible deviations from the Lorentz combining rule of collision diameters.