Phase transition behaviors of polyimide blends

We investigate phase behaviors of polyimide blends such as polyethermide (P EI)/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 weig ht 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 temperat ures of PAI/PEO systems appeared to be near or below the melting point of P EG. 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 fai rly well. (C) 2000 Elsevier Science Ltd. All rights reserved.