Lamellar Thickness of a Syndiotactic Polystyrene Determined from Small-angle X-ray Scattering and Transmission Electron Microscopy |
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Authors: | Wei-Po Liao Tsang-Lang Lin E M Woo Chi Wang |
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Affiliation: | (1) Department of Chemical Engineering, National Cheng Kung University, Tainan, 701, Taiwan, ROC;(2) Department of Engineering and System Science, National Tsing Hua University, Hsin-Chu, 300, Taiwan, ROC |
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Abstract: | Extensive morphological studies on a syndiotactic polystyrene (sPS) sample prepared from compression molding were carried out using small-angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). SAXS was conducted at 25![thinsp](/content/x7h3j627rq322386/xxlarge8201.gif) C as well as at 150![thinsp](/content/x7h3j627rq322386/xxlarge8201.gif) C to enhance the scattering contrast in order to obtain more reliable morphological parameters. The compression-molded sample was crystallized into a ![beta](/content/x7h3j627rq322386/xxlarge946.gif) orthorhombic crystal lattice characterized by wide-angle X-ray diffraction (WAXD). A similar weight fraction of crystallinity, ca. 0.37, was obtained from both WAXD and differential scanning calorimetry measurements.In addition to the scattering peak at a scattering vector of ca. 0.36 nm–1 attributable to the presence of lamellar/amorphous layers, anomalous scattering at the zero angle was found from the SAXS intensity profiles. Based on the Debye–Bueche theory, the scattering profile of this peculiar zero-angle scattering was deduced and was subtracted from the raw intensity profile to obtain the intensity profile exclusively associated with the lamellar/amorphous structure. A consistent long period was obtained for SAXS measured either at 25 or 150![thinsp](/content/x7h3j627rq322386/xxlarge8201.gif) C, provided that the appropriate subtraction of intensities due to the zero-angle scattering was conducted. Moreover, the lamellar thickness deduced from the one-dimensional correlation function was in good agreement with TEM results. A difference scattering pattern derived from SAXS measured at 150 and 25![thinsp](/content/x7h3j627rq322386/xxlarge8201.gif) C was obtained and a comparison of the morphological parameters was provided as well. |
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Keywords: | lamellar morphology SAXS syndiotactic polystyrene |
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