Authors:V. B. F. Mathot, R. L. Scherrenberg, M. F. J. Pijpers, and W. Bras
Ethylene-propylene (EP) and ethylene-octene (EO) copolymers polymerized with the aid of homogeneous vanadium and metallocene catalysts were compared by DSC and time-resolved simultaneous SAXS-WAXS-DSC at scanning rates of 10 and 20°C min−1 using synchrotron radiation. An EP copolymer with a density of 896 kg m−3 (about 89 mol % ethylene) after compression moulding gave orthorhombic WAXS reflections. The crystallinity as a function of temperature [wc(T)] calculated from these reflections using the two-phase model was in good agreement withwc(T) calculated fromcp measurements using DSC. Thecp measurements also enabled calculation of the baselinecp and the excesscp. The SAXS measurements revealed a strong change in the long period in cooling and in heating. The SAXS invariant as a function of temperature showed a maximum in both cooling and heating, which could be explained from the opposing influences of the crystallinity and the electron density difference between the two phases. Two EO copolymers with densities of about 871 kg m−3 (about 87 mol% ethylene) no longer showed any clear WAXS reflections, although DSC and SAXS measurements showed that these copolymers did crystallize. The similarity between the results led to the conclusion that the copolymers, though based on different catalyst systems — vanadium and metallocene — did not have strongly different sets of propagation probabilities of chain growth during polymerization. On the basis of a Monte Carlo simulation model of crystallization and morphology, based on detailed knowledge of the microchain structure, the difference between WAXS on the one hand and DSC and SAXS on the other could be explained as being due to loosely packed crystallized ethylene sequences in clusters. These do cause the density and the electron density of the cluster to increase (which is measurable by SAXS) and the enthalpy to decrease (which is measurable by DSC) but the clusters are too small and/or too imperfect to give constructive interference in the case of WAXS. Of an EP copolymer with an even lower ethylene content (about 69 mol %), the crystallization and melting processes could still be readily measured by DSC and SAXS, which proves that these techniques are eminently suitable for investigating the crystallization and melting behaviour of the copolymers studied.
Authors:Bernadett Bajnóczi, Zoltán May, Anna Ridovics, Máté Szabó, Géza Nagy, and Mária Tóth
, Jean 1969 : Smalt . Studies in Conservation, 14 , 47 – 61 .
P RADELL , T. – M OLERA , J. – S ALVADÓ , N. – L ABRADOR , A. 2010 : Synchrotronradiation micro-XRD in the study of glaze technology . Applied Physics, A99 , 407 – 417
Authors:Emese Szabó, P. Sipos, B. Kovács, D. Andrási, and Z. Győri
Osán, J., Török, Sz., Alföldy, B. and Falkenberg, G. (2004): Characterization of anthropogenic sediment particles after a transboundary water pollution of River Tisza using synchrotronradiation. Spectrochim. Acta 59, 701
Authors:Hermi F. Brito, Jukka Hassinen, Jorma Hölsä, Högne Jungner, Taneli Laamanen, Mika Lastusaari, Marja Malkamäki, Janne Niittykoski, Pavel Novák, and Lucas C. V. Rodrigues
more efficient materials, the interplay between these energy level schemes needs to be resolved.
The band gap energy of a material can usually be obtained from luminescence excitation measurements, though only by using synchrotronradiation due
Authors:P. S. Thomas, B. H. Stuart, N. McGowan, J. P. Guerbois, M. Berkahn, and V. Daniel
PIXE all provide elemental information, but cannot provide phase information and synchrotronradiation. XRD has provided valuable information about ochre phase analysis and composition, but is limited to crystalline phases and phases that are fairly
Authors:Stefano Gialanella, Fabrizio Girardi, Gloria Ischia, Ivan Lonardelli, Maurizio Mattarelli, and Maurizio Montagna
transformation of goethite and hematite were monitored by synchrotron powder diffraction at the high resolution ID31 beam-line of the European SynchrotronRadiation Facility in Grenoble, France. Capillary spinning on the axis of diffractometer was used to
Authors:Goio Etxebarria, Mikel Gomez-Uranga, and Jon Barrutia
Institut Laue-Langevin (ILL—the most powerful continuous source of neutrons in the world) and the European SynchrotronRadiation Facility (ESRF—the brightest source of X-rays in the world). the Nanocharacterisation Platform of the CEA (PFNC—a unique set of
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Tuck, D. M., Bierck, B. R. & Jaffé, P. R., 1998. Synchrotronradiation measurement of multiphase fluid saturation in porous media: experimental technique and error analysis. Journal of Contaminant Hydrology
Authors:Hsuan-I Liu, Bi-Chun Chang, and Kuan-Chia Chen
(TSMC) and Chunghwa Telecom tend to collaborate with foreign universities more often. In Nanotech, Academia Sinica collaborates with National Science Council of Ukraine frequently, followed by National SynchrotronRadiation Research Center (NSRRC) and