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(e ther 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 an d Fourier transform (FT-IR) spectroscopy. A composition-dependent single gl ass-transition temperature (T-g) in the PEDEK/PEI blends over a full compos ition range was observed; the sharp transition width and the T-g-compositio n relationship both suggest that the scale of mixing is fine and uniform. E vidence based on observation of the cold-crystallization peak and suppressi on of the blend crystallinity and melting peak also indicated intimate inte rmolecular mixing. The FT-IR result yielded further evidence that the physi cal interactions leading to miscibility were weak, with no apparent specifi c interactions between the constituent polymers. Relationships between stru ctures and interactions responsible for the miscibility in PEI and several ether-ketone-type polymers are briefly discussed.