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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 13: POSTERS Polymer Physics

CPP 13.1: Poster

Dienstag, 24. März 2009, 14:00–16:30, P3

Automatic mapping of WAXS fiber patterns and its application: Crystallization mechanisms in polypropylene — •Norbert Stribeck1, Ulrich Nöchel1, and Sérgio S. Funari21Universität Hamburg, Institut TMC, 20146 Hamburg, Germany — 2HASYLAB c/o DESY, 22603 Hamburg, Germany

In time-resolved WAXS studies thousands of patterns are recorded that must be mapped into reciprocal space and evaluated for structure evolution analysis. Crystallographers refine an approximation, but this takes time. The exact solution [1] for fiber orientation with respect to the detector plane is found. Then an automatic mapping and evaluation algorithm [2] is devised. For oriented polypropylene it returns weight crystallinities and crystallite sizes for two sets of crystallites that are differently oriented (c, a*). The method is applied in a study of crystallization mechanisms by WAXS [3] and SAXS [4]. At shallow quench we observe (1) decomposition of the amorphous melt, (2) a nucleation regime of several minutes in which crystallinity stays below 1% (latency period), (3) a growth regime with rapid growth of crystallinity. Begin and length of the latency period are different for c- and a*-set and vary as a function of undercooling.
 
[1] Stribeck Acta Cryst. (2009), doi:10.1107/S0108767308029772
[2] Stribeck et al. J. Appl. Cryst., submitted Sept 2008
[3] Stribeck et al., Macromolecules, submitted Nov 2008
[4] Stribeck et al., Macromolecules (2007), 40(13), 4535-4545

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