Stribeck N, Almendarez Camarillo A, Nöchel U, Bösecke P, Bayer RK. Early oriented isothermal crystallization of polyethylene studied by high-time-resolution SAXS/WAXS.
Anal Bioanal Chem 2006;
387:649-61. [PMID:
17089099 DOI:
10.1007/s00216-006-0907-2]
[Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2006] [Revised: 10/02/2006] [Accepted: 10/06/2006] [Indexed: 11/28/2022]
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.
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