Crystallization and melting behavior of poly(ethylene oxide) and its blend with styrene-based ionomer using time-resolved SAXS/WAXS experiments

Time-resolved synchrotron wide- and small-angle X-ray scattering experiments were used to investigate the crystallization behavior and microstructure development of neat poly(ethylene oxide) (PEO) and its 50/50 blend with ionomer containing 6.4 mol% of sodium acrylate. The apparent lateral crystal sizes D(1 2 0) and D(1 1 2)/(0 0 4) were derived from the WAXS profiles. It was found that D(1 2 0) and D(1 1 2)/(0 0 4) of PEO in the blend are almost independent of temperature and are smaller when compared to those of neat PEO sample. The evolution of morphological parameters extracted from time-resolved SAXS profiles such as the long period L, the lamellar crystal thickness lC and the amorphous layer thickness lA, shows that the crystallization process of neat PEO follows the nucleation theory. The lamellar crystal thickness lC shows a single linear dependence on inverse supercooling, over the whole temperature range investigated. In contrast, the crystallization process of PEO in the blend (i.e. in the presence of interactions with the ionomer) follows the nucleation theory only in the narrow supercooling range. It was found also that the morphology of the blend consists of a broad population of lamellar crystal thicknesses. During heating lamellae melt in the reversed sequence of their formation.