EFFECT OF PRESSURE ON POLYMER BLEND MISCIBILITY - A TEMPERATURE-PRESSURE SUPERPOSITION

In this paper, we report on how interaction strength varies with press ure and temperature for several polyolefin mixtures. We find that the interaction energies that govern phase behavior in polymer blends are only a function of density for UCST polyolefin blends far from a criti cal point. As a result, the effects of pressure on miscibility can be predicted for such blends from knowledge of the effects of temperature on the interactions combined with PVT data. This remarkable simplific ation appears to be related to the van der Waals nature of the interac tions between saturated hydrocarbons. Density dependence predicts the trends correctly for LCST polyolefin blends, but for these mixtures th e interactions depend in a more complex way on T and P.