Incompatibility of polymer solutions. I. Binodals and spinodals in the system polystyrene + polyisobutylene + toluene

The incompatibility of polystyrene (PS) and polyisobutylene (PIB) in toluene is characterized by binodals obtained from phase separation and spinodals obtained from light scattering at zero scattering angle. From these the interaction parameter χ₂₃, between unlike polymer segments was calculated. It appears to be dependent on molecular weight and composition. The nature of χ₂₃, especially its low value, is discussed.