TIT# Tensile Tests of Polypropylene Monitored by SAXS. Comparing the
     Stretch-Hold Technique to the Dynamic Technique
AUT# Stribeck, Norbert; N”chel, Ulrich; Funari, S‚rgio S.; Schubert, Tom
SOU# J. Polym. Sci. Polym. Phys. (2008), 46(7), 721-726
LOC# xv106
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APP#
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ABS# Advanced instrumentation at synchrotron beamlines facilitates
     considerable reduction of the exposure required for the recording of
     low-noise small-angle X-ray scattering (SAXS) patterns. Concerning the
     monitoring of tensile tests on polymer materials by SAXS this means that
     change-over from the stretch-hold technique to more practical dynamic
     straining is possible, although the strain rate is still by a factor of
     100 lower than that relevant in industry and service. As hard-elastic
     polypropylene (PP) is tested, considerably different scattering patterns
     are recorded after switching to the dynamic technique. Even though during
     exposure the elongation is no longer constant when applying the dynamic
     technique, the images collected in stretch-hold technique appear much
     more blurred. The observed immediate relaxation of nanostructure induced
     by stopping the extensometer is analyzed by means of the multidimensional
     chord distribution function (CDF): The extension of the crystalline
     lamellae is increasing. Their thicknesses are becoming non-uniform. The
     range of order is shortening. Cross-hatched lamellae are formed.