Van der Waals chain-molecule fluid in self-consistent field approximation:Some thermal properties

The van der Waals equation for a monomer is used to derive the equation of state for a fluid consisting of chain molecules of equal length. The evolut ion of a part of the diagram of state pertaining to liquid-vapor equilibriu m is treated for the case of an increase in the number of links in a molecu le. The dependences on the number of links n are found for the following pr operties of polymer fluid: the critical temperature T-c, the critical press ure p(c), the critical density rho (c), the critical compressibility z(c), the temperature of normal boiling, the Riedel parameter of similarity alpha , the acentric factor omega, and the enthalpy of vapor formation DeltaH(v). A comparison with the experimental data for n-alkanes and l-alkanols revea ls that the obtained dependences reflect qualitatively correctly the variat ion of the above-identified properties with an increase of the number of li nks in a molecule. For long chains (n much greater than 1), the scaling dep endences are determined for the properties of a chain-molecule fluid: T-c s imilar to 1 - n(-1/2), p(c) similar to n(-3/2), rho (c) similar to n(-1/2), z(c) similar to n(-1), alpha similar to n, omega similar to n(2/3), DeltaH (v) similar to n.