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ABSTRACT: In this work, the effect of zinc oxide (ZnO) concentration and shape on processing and properties of new biaxially oriented polypropylene (BOPP)-ZnO nanocomposites was studied. The use of spherical nanoparticles and nanorods was expected to differently influence the properties of the final material. Films of isotactic polypropylene prepared with different ZnO incorporation were biaxially oriented under conditions of temperature and strain rate that were similar to those encountered in a commercial film process. Scanning electron microscopy analysis was performed to visualize the dispersion degree of the ZnO nanoparticles in the polymer matrix and to observe the surface and the orientation of the elongated nanoparticles. Furthermore, the prepared ZnO-BOPP nanocomposites were evaluated for both mechanical and oxygen barrier property enhancement. A good combination of mechanical and oxygen barrier properties was obtained for the ZnO-BOPP films. This result makes the ZnO-BOPP nanocomposite a proper material for applications such as food packaging. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011
Journal of Applied Polymer Science 11/2010; 120(3):1616 - 1623. · 1.29 Impact Factor
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M K Van Bael,
E Knaepen,
A Kareiva,
I Schildermans,
R Nouwen,
J D'Haen,
M D'Olieslaeger,
C Quaeyhaegens, D Franco,
J Yperman,
J Mullens,
L C Van Poucke
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ABSTRACT: The preparation of precursors of bulk , and materials by coprecipitation-filtration of hydroxides or oxalates and sol-gel techniques is presented. Their properties are compared with those of products prepared by the conventional solid-state reaction method by means of TGA, FTIR, XRD, SEM, EDX and resistivity measurements.
Superconductor Science and Technology 12/1998; 11(1):82. · 2.66 Impact Factor
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ABSTRACT: In order to study the influence of strontium substitution on YBa2Cu4O8, two series of samples with composition Y:Sr:Ba:Cu=1−x:x:2:4 and Y:Ba:Sr:Cu=1:2−2x:2x:4 (x=0.0–1.0) were synthesized by a simple aqueous sol–gel method at 1 atmosphere oxygen pressure. Effects of strontium substitutions on the properties of the compounds were studied by thermogravimetric analysis, X-ray powder diffraction, scanning electron microscopy and resistivity measurements. It was unambiguously demonstrated that in both series strontium enters the structure at the barium positions. Nearly single-phase Y(Ba1−xSrx)2Cu4O8 superconducting samples for x=0.0–0.3 were obtained, when final heat treatment was carried out at 835°C for 70 h in flowing oxygen atmosphere. The critical temperature of the Y(Ba1−xSrx)2Cu4O8 is enhanced to 88 K at about 20% Sr substitution.
Physica C Superconductivity 307:209-220. · 1.01 Impact Factor
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M.K. Van Bael,
A. Kareiva,
R. Nouwen,
I. Schildermans,
G. Vanhoyland,
J. D’Haen,
M. D’Olieslaeger, D. Franco,
J. Mullens,
J. Yperman,
L.C. Van Poucke
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ABSTRACT: In this work the influence of replacing Cu by Ni or Co on the structural and superconducting properties of YBa2Cu4O8 is studied by means of XRD, TGA, SEM, EDX and resistivity measurements. The samples are prepared by the acetate–tartrate sol–gel method, which has proved to be very appropriate for the synthesis of Y-124 at 1 atm with even very small amounts of dopants. It is demonstrated that the transition temperature drastically decreases upon Co or Ni substitution, and that superconductivity is lost at 3% Ni and 6% Co doping. XRD measurements show that Ni and Co produce different structural effects to the orthorhombic YBa2Cu4O8 phase, possibly because they are introduced in different copper positions. Interesting results are obtained by additional substitution of Y by Ca in the Co- and Ni-doped samples: It is shown that the superconducting properties are enhanced in the samples with less than 3% Ni or 6% Co, and that superconductivity is even recovered in samples with more than 3% Ni or 6% Co.
International Journal of Inorganic Materials.
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ABSTRACT: Sodium cuprate with a high Cu(III) content was synthesized and characterized with emphasis on the determination of Cu(III). Results of multicomponent analysis, carried out in two independent laboratories employing several different methods, are compared and discussed. For Cu(III) determination, improved or newly developed iodometric and voltammetric methods were used. A good agreement on the high Cu(III) content (97–98% of total copper) was found. Virtually no peroxidic oxygen was found employing a specific photometric procedure. Other components, sodium and total copper, were determined by means of usual methods: inductively coupled plasma atomic emission spectroscopy (ICP-AES), atomic absorption spectroscopy (AAS), flame emission spectroscopy (FES) and ion selective electrode (ISE)/potentiometry. This preliminary interlaboratory characterization study showed that sodium cuprate, synthesized by the applied method, can be considered as a potential Cu(III) standard reference material.
Analytica Chimica Acta.
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ABSTRACT: Synthesis and characterization of γ-boehmite and γ-alumina nanoparticles with a platelet shape are described.First an environmentally friendly hydrothermal synthesis method is applied to form nanostructured γ-boehmite, starting from the hydrolysis of aluminium alkoxide. Subsequently γ-alumina nanopowder is obtained after calcination of the γ-boehmite at 600 °C.Transmission electron microscopy (TEM) reveals that the particle size of γ-AlOOH and γ-Al2O3 lies between 30 and 80 nm. Furthermore, the nanopowders have been characterized by photon correlation spectroscopy (PCS) and X-ray diffractometry (XRD).
Ceramics International.
