Mapping structural gradients in isotactic polypropylene using scanning wide-angle X-ray scattering

Research output: Contribution to journalArticle


The internal microstructure of injection-molded dogbone specimens of talc-filled isotactic polypropylene has been investigated using a home laboratory scanning wide-angle X-ray scattering setup, yielding two-dimensional maps of molecular orientation and ordering for cross-sections parallel and perpendicular to the flow direction with unprecedented details. In addition to demonstrating a high degree of alignment of both the iPP b-axis and the talc c-axis parallel to the sample wall normals, thus corroborating earlier reports, the synthesized maps also yield new insights into the molecular organization. We find an asymmetry in the orientation maps, which we ascribe to a lateral temperature gradient across the mold during solidification. This interpretation is supported by numerical simulations of heat transport during the solidification following material flow, leading to orientation maps in full qualitative agreement with the experimental data. Recent developments in X-ray scattering equipment, in particular fast-readout low-noise area detectors, have facilitated the present experiments, which demonstrate the usability of raster scanning for advanced polymer characterization.


  • Håvard Granlund
  • Jostein Bø Fløystad
  • Morteza Esmaeili
  • Eirik Torbjørn Bakken
  • Martin Bech
  • Per Erik Vullum
  • Erik Andreassen
  • Dag Werner Breiby
External organisations
  • Norwegian University of Science and Technology
  • Technical University of Munich
  • Foundation for Scientific and Industrial Research (SINTEF)
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Radiology, Nuclear Medicine and Medical Imaging


  • Injection molding, Isotactic polypropylene, Raster-scanning WAXS
Original languageEnglish
Pages (from-to)1867-1875
Number of pages9
Issue number7
Publication statusPublished - 2013 Mar 22
Publication categoryResearch
Externally publishedYes