On the basis of two-fluid polymer coordination solution model

an equation of state (EOS) for polymer mixtures is derived

and applied to pVT correlation of four polymer mixture systems (polyisobutene/cyclohexane

polyisobutene/benzene

polydimediylsiloxane/hexadimethyl-siloxane

polydimethyl siloxane/benzene). A satisfactory accuracy is obtained. A new concept named fluidity coefficient is proposed. It could be obtained from equilibrium properties (pVT data)

and used to predict the transfer properties.