CRYSTALLIZATION KINETICS AND POLYMORPHISM IN AROMATIC POLYKETONES (PEKEKK) WITH DIFFERENT MOLECULAR-WEIGHT

Simultaneous wide and small X-ray scattering (WAXS and SAXS) real time experiments using synchrotron radiation were performed to investigate poly-aryl(ether ketone ether ketone ketone) (PEKEKK) samples with dif ferent molecular weights obtained by precipitation polycondensation. I sothermal melt crystallization experiments, using two crystallization temperatures, T-c (differing by 10 degrees C) for each polymer grade w ere carried out. The phase transition temperature from polymorphic for m II to form I was investigated in the samples as obtained. The variat ion of the index of crystallinity during heating was shown to depend o n molecular weight. The index of crystallinity and X-ray long period v alues of the isothermal melt-crystallized samples observed at T-c and then at room temperature depend on the T-c values. For the lowest visc osity sample the microstructure is also molecular weight dependent. Av rami analysis of the 110(I) reflection leads to the conclusion that a similar crystallization mechanism takes place for the samples investig ated.