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Structure Refinement of High-Density Polyethylene Using X-Ray Powder Diffraction Data and the Rietveld Method

Published online by Cambridge University Press:  06 March 2019

Kenneth B. Schwartz
Affiliation:
Corporate Technology Raychem Corporation, Menlo Park, CA 94025
Robert B. Von Dreele
Affiliation:
LANSCE Los Alamos National Laboratory Los Alamos, NM 87545
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Abstract

A full structure analysis of a completely crystallized sample of high-density polyethylene (HDPE) has been achieved using x-ray powder diffraction data collected on a laboratory-based powder diffractometer. The structure refinement is performed using the Rietveld method and includes refinement of the carbon and hydrogen atomic positions and temperature factors. The C-C and C-H bond distances and the C-C-C bond angle along the polyethylene chain have been calculated from the refined atomic positions and are in very good agreement with previous experimental and modelling determinations. Evaluations of the pseudo-Voigt profile parameters for Lorentzian strain broadening and me Scherrer coefficient for Gaussian broadening yield reasonable values for microstrain and particle size for this sample. Refinement of the preferred orientation parameter indicates that the HDPE flakes consist of platy crystals or lamellae that are packed normal to the diffraction vector.

Type
Research Article
Copyright
Copyright © International Centre for Diffraction Data 1995

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