The exchange energy parameter Xu of Flory new polymer solution theory could be evaluated from thermodynamic interaction parameter X which was determined by inverse gas-liquid chromatography. By using this value of X12 together with S1/S2

the ratio of contact surface area per unit characteristic volume (hard core volume) for polymer and solvent

the interaction parameters X

for polydimethylsiloxane

polyisobutylene

natural rubber and polystyrene with solvents were calculated

and plotted as X vs.2

the segment fraction of polymer. The values of X thus calculated were in good agreement with the experimental values. Moreover

the volume change in mixing VE/V0 and enthalpy of mixing corrected to infinitely dilute solution oi polymer ΔHM∞ were calculated with these parameters

and agreed with the observed values.