A BORN-GREEN-YVON INTEGRAL-EQUATION TREATMENT OF COMPRESSIBLE LATTICEMIXTURES

The statistical thermodynamics of compressible multicomponent lattice mixtures is developed using the Born-Green-Yvon (BGY) integral equatio n technique. Expressions for the internal energy, Helmholtz free energ y, chemical potential and equation of state are derived, and the route s to the volume, Gibbs energy, and noncombinatorial entropy are discus sed. We use these results to study the phase separation behavior of a theoretical polymer blend which exhibits both an upper and lower criti cal solution temperature, focusing primarily on the spinodal. The effe cts of changing the pressure, polymer chain length, lattice coordinati on number, and interaction energies are also investigated.