| Abstract
| - Time-resolved (TR) small-angle X-ray (SAXS) experiments wereconducted to monitor thedevelopment of microstructure and crystallinity in neat PEO and arepresentative composition from four,melt-miscible PEO blends. Although crystal thickening was notobserved directly during the time scaleof the experiments, comparison of the microstructural parametersobtained from the analysis of theTRSAXS data with those determined from static SAXS (forwell-crystallized samples) indicated differentrates of crystal thickening for rapidly vs slowly crystallizingsystems. An Avrami-like expression wasused to track the kinetic evolution of experimental invariants duringcrystallization. A generalized four-parameter model was proposed which, in addition to the two “Avrami”exponents, included factors thataccount for the nonzero crystallinity at the start of the SAXS run andfinite lamellar stacks at the endof the run. The model is reduced to three parameters for zeroinitial crystallinity. The three-parameterversion could be used successfully to fit the TRSAXS data of the blends(which do not exhibit initialcrystallinity), while the four-parameter approach offered a better fitfor neat PEO crystallized at 45 °C.The model was further used to estimate bulk crystallinities as afunction of time for neat PEO and thestrongly interacting blends. These values agree favorably withthose measured using DSC.
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