Phase transition behaviors of polyimide blends

We investigate phase behaviors of polyimide blends such as polyethermide (PEI)/polystyrene (PS), PEI/polyamideimide (PAI), PEI/polyethyleneoxide (PEO), and PAI/PEO systems. Our sample systems exhibit lower critical solution temperature (LCST) phase behaviors. In the PEI/PS system, phase transition occurred near or above the glass transition temperature (Tg) of PS and the critical temperature of the system increased with decreasing molecular weight of PS. For PEI/PAI and PEI/PEO systems, the critical temperature of PEI/PAI system is higher than that of PEI/PEO system. Phase transition temperatures of PAI/PEO systems appeared to be near or below the melting point of PEO. Theoretically, we employed the double-lattice model with a perturbation term to account for the specific interactions between polymer chains. The proposed model describes phase behaviors of the polyimide blend systems fairly well.