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Authors
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Scudla, J. ; Raab, M. ; Eichhorn, K.-J. ; Strachota, A.
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Title
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Formation and transformation of hierarchical structure of b-nucleated polypropylene characterized by X-ray diffraction, differential scanning calorimetry and scanning electron microscopy
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Date
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25.08.2003
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Number
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10843
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Abstract
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Commercial grade isotactic polypropylene has been modified with a specific β-nucleant (<i>N</i>,<i>N</i>′-dicyclohexylnaphthalene-2,6-dicarboxamide) in two concentrations (0.03 and 0.10 wt%). Specimens for structural characterization have been prepared by injection moulding, subsequent melting and re-crystallization or solid-state drawing at 100 °C. Individual levels of hierarchical structure, including molecular orientation, have been characterized by a combination of wide angle X-ray scattering (WAXS), differential scanning calorimetry and scanning electron microscopy. Based on the analysis <br />of the azimuthal reflections (110) and (300), the Hermans orientation functions have been calculated separately for the crystalline phases α and β. Besides the longitudinal orientation along the injection-moulding direction, β-crystallites tilted to the injection-moulding direction have been found. Upon thermal treatment the fraction of the crystalline β-phase has decreased and molecular alignment within the crystalline regions has improved. During solid-state drawing the fraction of the crystalline β-phase was markedly decreasing with increasing draw ratio, while the overall crystallinity has not changed but slightly. The experiments have also revealed a disruption of molecular alignment at the beginning of the drawing process and subsequent distinct improvement of molecular orientation along the draw direction in crystallites α and β. The Hermans orientation functions provided by the WAXS analysis have been compared with recently published data obtained with similar specimens by polarized photoacoustic spectroscopy.
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Publisher
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Polymer
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Wikidata
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Citation
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Polymer 44 (2003) 4655-4664
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DOI
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https://doi.org/10.1016/S0032-3861(03)00287-8
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Tags
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