MISCIBILITY AND CRYSTALLIZATION BEHAVIOR OF SOLUTION-BLENDED PEEK PI BLENDS/

Miscibility and crystallization behavior of solution-blended poly(ethe r ether ketone)/polyimide (PEEK/PI) blends were investigated by using DSC, optical microscopy and SAXS methods. Two kinds of PIs, YS-30 and PEI-E, which consist of the same diamine but different dianhydrides, w ere used in this work. The experimental results show that blends of PE EK/YS-30 are miscible over the entire composition range, as all the bl ends of different compositions exhibit a single glass transition tempe rature. The crystallization of PEEK was hindered by YS-30 in PEEK/YS-3 0 blends, of which the dominant morphology is interlamellar. On the ot her hand, blends of PEEK/PEI-E are immiscible, and the effect of PEI-E on the crystallization behavior of PEEK is weak. The crystallinity of PEEK in the isothermally crystallized PEEK/YS-30 blend specimens decr eases with the increase in PI content. But the crystallinity of PEEK i n the annealed samples almost keeps unchanged and reaches its maximum value, which is more than 50%. The spherulitic texture of the blends d epends on both the blend composition and the molecular structure of th e PIs used. The more PI added, the more imperfect the crystalline stru cture of PEEK. (C) 1998 John Wiley & Sons, Inc.