Two-Dimensional X-ray Diffraction Correction Factors and Analysis: A Starting Point for Quantitative Investigation of High-Density Crosslinked Polyethylene

Burns, Nicholas
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University of Guelph

High-Density Crosslinked Polyethylene (PEX) poses a difficult challenge to x-ray scattering as a means to generate quantitative high-resolution radial distribution functions (HR-RDF). First, constituent elements with low atomic numbers produce weak coherent signals. Second, semi-crystalline composition requires high flux for measurement of weak amorphous signals while avoiding saturation by intense crystalline reflections. Third, crystalline preferred orientation requires generation of the three-dimensional structure function S(q). PEX’s challenge is addressed, one, by implementation of a unique tilted geometry providing access to higher reciprocal space, improving dynamic range and signal-to-noise. Two, a non-traditional pixel gain correction calculated in experimental conditions. Three, a novel methodology for correcting parallax and topography distortions implemented using only a lab standard. Concertedly, a two-dimensional S(q) was generated out to 35 Å−1 as a starting point for three-dimensional analysis. Using a single orthorhombic unit cell, HR-RDFs were modelled for all phases and the crystalline phase was successfully Rietveld refined.

XRD, Polyethylene, Diffraction, X-ray, Xray, Synchrotron, Perkin-Elmer, Flat Panel, Area Detector, Flood Field, Parallax, Topography, Distortions, PEX, Radial Distribution, Pair Distribution, RDF, PDF, Gain, Corrections, Nickel, Silicon, Geometry