Dresden 2009 – wissenschaftliches Programm
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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. Funari2 — 1Universität 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