Vapor-liquid equilibrium ratios (K-wi(infinity) values) for hexane at infinite dilution in propylene + impact polypropylene copolymer (ICP-PP) and ethylene + ICP-PP systems were measured at temperatures 323.2, 343.2 and 363.2 K and pressures up to 2.4 MPa using a chromatographic technique. The solubilities of propylene in polypropylene and those of propylene, ethylene, and hexane in ICP-PP were measured. The PVT properties of the polypropylene and ICP-PP were also studied. These data were used to determine the pure component and binary interaction parameters for the Sanchez-Lacombe equation of state (S-L EOS). The K-w1(infinity) values were predicted by using the S-L EOS with binary parameters evaluated by correlation of phase-equilibrium data of binary systems. Good agreement between the experimental and calculated K-w1(infinity) values was obtained by optimizing the equation parameters.