Blends of a novel high-temperature poly(oxy-1,4'-diphenyleneoxy-1, 4-phenylenecarbonyl-1,4-phenylene) with poly(ether imide): Structure, interaction, and miscibility

Polymer miscibility has been discovered in a blend system comprising poly(ether imide) (PEI) and a new poly(ether diphenyl ether ketone) (PEDEK). The miscibility of the PEDEK/PEI polymer system (quenched from the molten state) was investigated in this study using differential scanning calorimetry and Fourier transform (FT-IR) spectroscopy. A composition-dependent single glass-transition temperature (T(g)) in the PEDEK/PEI blends over a full composition range was observed; the sharp transition width and the T(g)-composition relationship both suggest that the scale of mixing is fine and uniform. Evidence based on observation of the cold-crystallization peak and suppression of the blend crystallinity and melting peak also indicated intimate intermolecular mixing. The FT-IR result yielded further evidence that the physical interactions leading to miscibility were weak, with no apparent specific interactions between the constituent polymers. Relationships between structures and interactions responsible for the miscibility in PEI and several ether-ketone-type polymers are briefly discussed.