Phase Behavior and Rhythmically Grown Ring-Banded Spherulites in Blends of Liquid Crystalline Poly(aryl ether ketone) and Poly(aryl ether ether ketone)

Abstract

Phase behavior and rhythmically grown ring-banded spherulites in thin films of liquid crystalline poly(aryl ether ketone) (LC-PAEK) and poly(aryl ether ether ketone) (PEEK) blends have been investigated by differential scanning calorimetry (DSC), polarized light microscopy (PLM), atomic force microscopy (AFM), transmission electron microscopy (TEM), and electron diffraction (ED) techniques. The results show that the composition of the blends has great effect on the phase behavior and structure. Thin films of pure LC-PAEK and PEEK crystallized from the melts exhibit typical mosaic and spherulitic structures, respectively. For the blends with higher LC-PAEK contents (>50%), the two components are miscible at the molecular level in the melting state, and a phase separation takes place during the cooling process, as a result of the competition between the phase separation and the LC-PAEK phase transition, resulting in an unusual ring-banded spherulite. The bright core and rings of the ring-banded spherulites ...