Analysis of the degree of crystallinity in interpenetrating spherulites of poly(ethylene succinate) and poly(ethylene oxide) blends using pulsed NMR

The degree of crystallinity (φ) in interpenetrating spherulites, whereby spherulites of one component continue to grow inside those of the other component, was examined for the blends of poly(ethylene succinate) (PES) and poly(ethylene oxide) (PEO) using pulsed nuclear magnetic resonance. The value of φ for PES increased with PEO blending and was slightly dependent on the blend composition when crystallized below ~65 °C. However, φ for PEO monotonically decreased with the PES content in the blends and was dependent on the blend composition. The composition dependence of φ is discussed based on the change in temperature at which the molecular transport is frozen with the blend composition. The effect of secondary crystallization, which is only relevant for PEO, was taken into account when determining φ. The amount of crystals of both constituents in the blends primarily depended on the blend composition.