TY - JOUR
T1 - Mapping structural gradients in isotactic polypropylene using scanning wide-angle X-ray scattering
AU - Granlund, Håvard
AU - Fløystad, Jostein Bø
AU - Esmaeili, Morteza
AU - Bakken, Eirik Torbjørn
AU - Bech, Martin
AU - Vullum, Per Erik
AU - Andreassen, Erik
AU - Breiby, Dag Werner
PY - 2013/3/22
Y1 - 2013/3/22
N2 - 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.
AB - 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.
KW - Injection molding
KW - Isotactic polypropylene
KW - Raster-scanning WAXS
U2 - 10.1016/j.polymer.2013.01.055
DO - 10.1016/j.polymer.2013.01.055
M3 - Article
AN - SCOPUS:84874943730
SN - 0032-3861
VL - 54
SP - 1867
EP - 1875
JO - Polymer
JF - Polymer
IS - 7
ER -