A procedure is used to analyze small-angle neutron-scattering (SANS) data from a pressurized polymer blend mixture (deuterated polystyrene/polyvinylmethylether). The Lattice-Fluid (LF) equation-of-state model is used along with a compressible random phase approximation (RPA) in order to obtain free volume fractions and intermonomer interaction potentials. Solving the two sets of equations (LF and RPA) self-consistently within the fitting procedure to the SANS data provides an improvement over the familiar incompressible RPA model. In this approach, the free volume fraction is the main varying pa rameter. Intermonomer interaction potentials were found to depend on pressure (weakly) and temperature (linearly).