The irascibility of a poly (ether imide)/phenolphthalein poly (ether ether ketone) blend was determined by viscometry. The results ob ained indicate that the Huggins coefficients of the blends exhibit positive deviation from simple additivity

while the inherent viscosities of the blends exhibit negative deviation. The a values of viscometry

calculated from these parameters are all >0. It is obvious that the blends are miscible within the whole composition range.