NOVEL MORPHOLOGY IN RING-BANDED SPHERULITES FROM SINGLE-PHASE MIXTURES OF POLY(EPSILON-CAPROLACTONE) WITH POLY(STYRENE-CO-ACRYLONITRILE)

Novel morphology of ring-banded spherulites in the surface of silon-ca prolactone)/poly(styrene-co-acrylonitrile) (PCL/SAN) blends was discov ered and studied by SEM and TEM. The ring-banded spherulites separate into those exhibiting a very dark contrast, of relatively regular bund les of lamellae and others appearing with a much brighter intensity, o f a coarse and irregular aggregates of lamellae. The origin of the nov el morphology is not due to different crystalline structures as in the case of isotactic polypropylene because only one crystal structure ex ists in PCL/SAN blends. The formation may reflect whether spherulites in PCL/SAN blends are nucleated at the bottom surface or at the top (f ree) surface.