TIT# Analysis of SAXS Fiber Patterns by Means of Projections
AUT# Stribeck, N.
SOU# ACS Symp. Ser. (2000), 739, 41-56
LOC# xv039 @selbst.ftx
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ABS# Results of two methods for the quantitative analysis of two-dimensional
     (2D) small-angle X-ray scattering (SAXS) patterns with fiber symmetry
     are presented. Experimental data originate from studies of
     poly(ether ester) (PEE) thermoplastic elastomer materials recorded during
     straining experiments at a synchrotron beamline. The first steps in both
     methods are similar. By suitable projection of the 2D image data onto a
     line (longitudinal scattering, first method) or onto a plane (transverse
     scattering, second method) scattering curves are extracted, which finally
     can be analyzed in terms of two-phase structural models considering soft
     domains and hard domains inside the PEE. The studied longitudinal
     scattering in principal is one-dimensional and originates from chords
     crossing the soft and hard domains parallel to the direction of strain
     only. From these curves interface distribution functions (IDF) are
     computed and analyzed using an advanced stacking model. Not only the
     average domain heights, but four parameters characterizing each of two
     domain height distributions (hard and soft domains) are determined as a
     function of elongation. With several PEE materials strong equatorial
     scattering is observed during elongation. The equatorial scattering is
     similar to the frequently discussed void scattering but originates from
     an ensemble of rodlike soft domains (needles) in the sample, oriented
     parallel to the direction of strain. It can be studied using the second
     method. From the transverse scattering the 2D chord distribution is
     computed, from which the diameter distribution of the soft needles can
     be extracted. It is investigated as a function of strain.