Rhythmic growth of ring-banded spherulites in blends of liquid crystalline methoxy-poly(aryl ether ketone) and poly(aryl ether ether ketone)

Rhythmic growth of ring-banded spherulites in blends of liquid crystalline methoxy-poly(aryl ether ketone) (M-PAEK) and poly(aryl ether ether ketone) (PEEK) has been investigated by means of differential scanning calorimetry (DSC), polarized light microscopy (PLM), and scanning electron microscopy (SEM) techniques. The measurements reveal that the formation of the rhythmically grown ring-banded spherulites in the M-PAEK/PEEK blends is strongly dependent on the blend composition. In the M.-PAEK-rich blends, upon cooling, an unusual ring-banded spherulite is formed, which is ascribed to structural discontinuity caused by a rhythmic radial growth. For the 50:50 M-PAEK/PEEK blend, ring-banded spherulites and individual PEEK spherulites coexist in the system. In the blends with PEEK as the predominant component, M-PAEK is rejected into the boundary of PEEK spherulites. The cooling rate and crystallization temperature have great effect on the phase behavior, especially the ring-banded spherulite formation in the blends. In addition, the effects of M-PAEK phase transition rate and phase separation rate on banded spherulite formation is discussed.