Small-angle X-ray scattering on the ChemMatCARS beamline at the Advanced Photon Source: a study of shear-induced crystallization in polypropylene.

The first ever time-resolved small-angle X-ray scattering (SAXS) data from the undulator 15-ID-D beamline (ChemMatCARS) are presented. A 1.3 A (9.54 keV) X-ray beam was selected to study the structure development in a polypropylene sample during shear-induced crystallization. A Linkam CSS450 shear cell provided the temperature and shear control. The polypropylene was first melted and then quenched to the crystallization temperature, where a step shear was applied. The SAXS data were collected using a Bruker 6000 CCD detector, which provided images of excellent resolution. The SAXS images (with 180 degrees rotational symmetry) indicated that the polypropylene crystallizes with a high degree of anisotropy, and the lamellae are oriented perpendicular to the flow direction.