THE FORMATION OF RING-BANDED SPHERULITES OF POLY(EPSILON-CAPROLACTONE) IN ITS MISCIBLE MIXTURES WITH POLY(STYRENE-CO-ACRYLONITRILE)

Ring-banded spherulites in polymer blends of poly(epsilon-caprolactone ) (PCL) and poly(styrene-co-acrylonitrile) (SAN) were investigated by optical microscopy equipped with a digital image analysis system. PCL/ SAN blends exhibit not only spherulites with a Maltese cross, but also distinct extinction rings. The periodic distance of rings changes wit h blend ratio and crystallization temperature and was plotted as a fun ction of the undercooling and overall mobility of the mixtures, respec tively. It was found that the overall mobility of chain segments in th e mixtures could be mainly attributed to the origin of the formation o f ring-banded spherulites. It was believed that for the first time a q uantitative experimental result was obtained about the relationship of periodic distance of rings and the overall mobility of the mixtures. This relationship may be useful to explain the formation mechanism of ring-banded spherulites in polymer blends or even in homopolymers in t he future. (C) 1977 Elsevier Science Ltd.