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

Granlund, Håvard; Fløystad, Jostein Bø; Esmaeili, Morteza; Bakken, Eirik Torbjørn; Bech, Martin LU ; Vullum, Per Erik; Andreassen, Erik and Breiby, Dag Werner (2013) In Polymer 54(7). p.1867-1875
Abstract

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.... (More)

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.

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author
publishing date
type
Contribution to journal
publication status
published
subject
keywords
Injection molding, Isotactic polypropylene, Raster-scanning WAXS
in
Polymer
volume
54
issue
7
pages
9 pages
publisher
Elsevier
external identifiers
  • scopus:84874943730
ISSN
0032-3861
DOI
10.1016/j.polymer.2013.01.055
language
English
LU publication?
no
id
1bf1af74-8a71-4e23-90ca-0f53bdb6d170
date added to LUP
2019-08-12 15:03:50
date last changed
2019-08-16 14:33:13
@article{1bf1af74-8a71-4e23-90ca-0f53bdb6d170,
  abstract     = {<p>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.</p>},
  author       = {Granlund, Håvard and Fløystad, Jostein Bø and Esmaeili, Morteza and Bakken, Eirik Torbjørn and Bech, Martin and Vullum, Per Erik and Andreassen, Erik and Breiby, Dag Werner},
  issn         = {0032-3861},
  keyword      = {Injection molding,Isotactic polypropylene,Raster-scanning WAXS},
  language     = {eng},
  month        = {03},
  number       = {7},
  pages        = {1867--1875},
  publisher    = {Elsevier},
  series       = {Polymer},
  title        = {Mapping structural gradients in isotactic polypropylene using scanning wide-angle X-ray scattering},
  url          = {http://dx.doi.org/10.1016/j.polymer.2013.01.055},
  volume       = {54},
  year         = {2013},
}