lory's equation-of-state theory with modified combinary rules was applied to estimate the thermodynamic parameters of poly (ethylene oxide ) and poly(vinyl acetate) blending system. For this purpose

heats of mixing

densities

thermal expansion coefficients and thermal pressure coefficients for this system were measured. The heats of mixing of blends in all the range of compositions by application of Hess's law were negative. And the interactionparameters

the exchange enthalpy and the excess volumes were negative too. These results supported strongly from the experimental and the theoretical point of view that this blending system are miscible.