Session D40 - Poster Session I.
POSTER session, Monday afternoon, March 12
Exhibit Hall, Washington State Convention Center
Time-resolved simultaneous wide- and small-angle x-ray scattering experiments were used to investigate crystallization and microstructure development of two poly(ethylene oxide) molecular weight fractions and their mixtures, at several crystallization temperatures and compositions. In addition, crystallization of melt-miscible blends of PEO with narrow molecular weight fractions of PMMA and a 50/50 styrene-hydroxystyrene random copolymer was also investigated. During isothermal crystallization, secondary crystallization was observed for both the low (Mw = 50K, PDI = 1.07) and high (Mw = 334.5K, PDI = 1.14) molecular weight PEO fractions. The decrease in SAXS long periods observed at early crystallization times (2-3 nm) was similar to that noted previously for polydisperse PEO [Macromolecules 33, 4842 (2000)] and lamellar insertion appears to be the likely origin of this behavior. The origin of the behavior observed during crystallization of the PEO mixtures, as well as that of the weakly- and strongly-interacting PMMA and SHS blends, will be discussed.