Effect of poly(butylene succinate) crystals on spherulitic growth of poly(ethylene oxide) in binary blends of the two substances

Abstract

The effects of the lamellar growth direction, extinction rings, and spherulitic boundaries of poly(butylene succinate) (PBSU) on the spherulitic growth of poly (ethylene oxide) (PEO) were investigated in miscible blends of the two crystalline polymers. In the crystallization process from a homogeneous melt, PBSU first developed volume-filling spherulites, and then PEO spherulites nucleated and grew inside the PBSU spherulites. The lamellar growth direction of PEO was identical with that of PBSU even when the PBSU content was about 5 wt %. PEO, which intrinsically does not exhibit banded spherulites, showed apparent extinction rings inside the banded spherulites of PBSU. The growth rate of a PEO spherulite, GPEO, was influenced not only by the blend composition and the crystallization temperature of PEO, but also by the growth direction with respect to PBSU lamellae, the boundaries of PBSU spherulites, and the crystallization temperature of PBSU, TPBSU. The value of G PEO first increased with decreasing TPBSU when a PEO spherulite grew inside a single PBSU spherulite. Then, GPEO decreased when TPBSU was further decreased and a PEO spherulite grew through many tiny PBSU spherulites. This behavior was discussed based on the aforementioned factors affecting G PEO. ©2009 Wiley Periodicals, Inc.