Combined techniques of Raman spectroscopy and synchrotron two-dimensional x-ray diffraction for in situ study of anisotropic system: Example of polymer fibers under deformation

Abstract

High pressure stability of bismuth sillenite: A Raman spectroscopic and x-ray diffraction studyMapping the three-dimensional strain field around a microindentation on silicon using polishing and Raman spectroscopy Simultaneous measurements of Raman spectroscopy and synchrotron two-dimensional ͑2D͒ wide-angle x-ray diffraction ͑WAXD͒ have been successfully demonstrated for in situ study of an anisotropic system: isotactic polypropylene ͑iPP͒ fiber under tensile deformation. A fiber-optic probe was used to remotely deliver the incident laser beam on the sample as well as to collect the Raman signal based on the confocal arrangement, whereas high resolution 2D WAXD patterns were obtained simultaneously at the same position during deformation of polymers. The combined techniques yielded complementary information on the molecular structural evolution in both crystalline and amorphous phases. 2D WAXD results showed that the ␣-form iPP crystals were converted into the mesophase upon stretching at room temperature. Corresponding Raman spectra showed that characteristic bands from the crystal phase became weaker or disappeared during the transition from the crystal phase to the mesophase. However, the bands associated with the helical structure were still present, indicating the remainder of the helical conformation in the mesomorphic phase. The persistence of the Raman band at 812 cm Ϫ1 in the mesophase implied that the structural difference between the crystal phase and the mesophase in iPP is due to the packing defects, rather than the conformational deviations from the ͑•••TGTG•••͒ sequence in chains. The variations in the Raman intensity ratio (I812/I843) indicated that the overall orientation of the fiber increased during stretching. The demonstrated techniques will be particularly useful for in situ studies of anisotropic polymers, where orientational dependent structural information from both crystalline and amorphous phases needs to be collected simultaneously.

In situsimultaneous Raman/high-resolution X-ray powder diffraction study of transformations occurring in materials at non-ambient conditions

“…Simultaneous experiments involving Raman and/or X-ray techniques were at first attempted on polymers in the late 1990s (Bogg et al, 1995;Bryant et al, 1998;Rastogi et al, 1998), but only from 2003 did a large number of papers appear reporting simultaneous multi-technique experiments, viz. SAXS/WAXS/XAS (Beale et al, 2006), Raman/XAS (Beale et al, 2005) and Raman/XRD, analyzing mainly poorly crystalline polymers (Ran et al, 2003;Davies et al, 2005Davies et al, , 2006van Hooy-Corstjens & Rastogi, 2006) or catalysts (Tinnemans et al, 2006). A simultaneous Raman/XRPD experiment, employing a conventional diffractometer, was reported by Tashiro et al (2002).…”

Probing structure and orientation in polymers using synchrotron small- and wide-angle X-ray scattering techniques

“…fiber spinning and film extrusion) [19], in in situ X-ray studies. The combined characterization techniques involving synchrotron X-rays and other analytical probes, such as light scattering [20], Raman and IR spectroscopy [21][22][23], are also feasible to cover a broad range of structural and functional information.…”

Temperature dependence of molecular conformation in uniaxially deformed isotactic polypropylene investigated by combination of polarized FTIR spectroscopy and 2D correlation analysis

“…High flux X‐ray scatterings, such as wide and small angle scattering (WAXD/SAXS), are suitable choices for investigating crystallization and deformation behavior of semicrystalline polymers. However, these two methods are less sensitive to structure changes in amorphous phase . Moreover, in the case of SAXS observation, the appearance of cavitations during neck propagation would enhance the contrast with surrounding polymeric matrix and overlay the crystalline signal, thus limiting the evaluation of structure change to a certain extent .…”