The degree of crystallinity and segmental mobility in interpenetrating spherulites of poly(butylene succinate) and poly (ethylene oxide)

The influence of poly(butylene succinate) (PBS) crystals on the crystallinity of poly(ethylene oxide) (PEO) in PBS/PEO blends, which exhibit interpenetrating spherulites, was examined. The degree of crystallinity, phi of each component was obtained by pulsed nuclear magnetic resonance (NMR). The value of phi of PBS exhibited a maximum that was larger than that of the homopolymer, whereas PEO exhibited a nearly constant phi throughout the composition. The dilution effect, order of crystallization, and change in the glass transition temperature upon blending were discussed as factors contributing to the phi. PEO exhibited an apparent secondary crystallization, where phi gradually increased and the mobility of the chain segments was suppressed. The secondary process of PBS, on the other hand, was nearly negligible.