Structural and morphological rearrangements in quenched poly(ethylene) by simultaneous SAXS/WAXS

Full Paper: Structure formation by crystallization from the melt in a wide range of cooling rates (0.08-1000 degreesC/ s) in law-density polyethylene has been studied by simultaneous small- and wide-angle X-ray scattering at the synchrotron radiation source of DESY. The occurrence of two periodiciti es, characterized by different angular position of Bragg's maxima, was obse rved, pointing to the existence of two types of lamellar stacks, associated with two different long period values L-1 and L-2 (L-1 > L-2). L-1 depends on the cooling rate, whereas L-2 is almost constant. A comparison with iso tactic polypropylene is performed, where a similar phenomenon takes place. While in the case of i-PP a definite correlation between the morphological features and the lamellar structure is observed and quantitatively demonstr ated, the same cannot be stated in the case of PE. [GRAPHICS] Long periods corresponding to the maxima positions of the two peaks used to fit the SAXS patterns of PE vs. cooling rate.