MSc Candidate

Nicholas Burns

Abstract

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 -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.

Examination Committee

• Dr. Eric Poisson, Chair
• Dr. Stefan Kycia, Advisor
• Dr. John Dutcher
• Dr. De-Tong Jiang