title: Early oriented isothermal crystallization of polyethylene studied by high-time-resolution SAXS/WAXS.
abstract: During cooling from the quiescent melt of a highly oriented polyethylene rod, highly oriented proto-lamellae are formed first, which are not crystalline. This is shown in scattering data which are recorded on two-dimensional detectors with a cycle time of 1 s and an exposure of 0.1 s. In the experiments small-angle X-ray scattering (SAXS) and wide-angle X-ray scattering (WAXS) are registered simultaneously during the first 3 min after quenching to a crystallization temperature. A non-uniform thickness between 20 and 100 nm is characteristic for the ensemble of proto-lamellae. During the first minute of isothermal treatment the number of proto-lamellae slowly increases without a change of the thickness distribution. As crystallization starts, the crystallites are not oriented in contrast to the proto-lamellae. During crystallization the layer thickness distribution narrows. The number of lamellae rapidly increases during the following 2 min of isothermal treatment (at 128 degrees C and 124 degrees C). The results are obtained by interpretation of the WAXS and of the multidimensional chord distribution function (CDF), a model-free real-space visualization of the nanostructure information contained in the SAXS data.
authors.affiliation: Institute of Technical and Macromolecular Chemistry, University of Hamburg, Bundesstr. 45, 20146, Hamburg, Germany. Norbert.Stribeck@desy.de
authors.forename: N
authors.initials: N
authors.lastname: Stribeck
authors.forename: A
authors.initials: A
authors.lastname: Almendarez Camarillo
authors.forename: U
authors.initials: U
authors.lastname: Nöchel
authors.forename: P
authors.initials: P
authors.lastname: Bösecke
authors.forename: R K
authors.initials: RK
authors.lastname: Bayer