References of "Rulmont, André"
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See detailPolymer layered silicate/carbon nanotube nanocomposites : Morphological and rheological properties
Peeterbroeck, Sophie; Alexandre, Michaël ULg; Nagy, Janos B et al

in Macromolecular Symposia (2005), 221

Morphological and rheological properties of new ternary nanocomposites based on ethylene vinyl acetate copolymers (EVA), commercial organo-modified clays (organoclays) and purified multi-walled carbon ... [more ▼]

Morphological and rheological properties of new ternary nanocomposites based on ethylene vinyl acetate copolymers (EVA), commercial organo-modified clays (organoclays) and purified multi-walled carbon nanotubes (MWNTs), prepared via direct melt blending, have been evaluated. For sake of comparison, the corresponding binary compositions, i.e., EVA filled with either organoclays or MWNTs, have been investigated as well. While extensive exfoliation can be observed for binary EVA/clay nanocomposites, the addition of MWNTs appears to limit clay exfoliation. Rheological properties show that both clay and MWNTs increase the elastic modulus of the nanocomposites, reflecting the high degree of nanoparticle interconnectivity that can be found in these materials. [less ▲]

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See detailSurface modification of as-synthesized lamellar mesostructured silica obtained by liquid crystal templating
Henrist, Catherine ULg; Vogels, C.; Rulmont, André ULg et al

in New Journal of Chemistry (2005), 29(8), 1017-1021

We report a study of lamellar silica phase silylation, starting from as-synthesized silica, without the usual heat treatment step. Characterizations of the modified silica include X-ray diffraction ... [more ▼]

We report a study of lamellar silica phase silylation, starting from as-synthesized silica, without the usual heat treatment step. Characterizations of the modified silica include X-ray diffraction, thermal analysis, electron microscopy and solid state NMR. Special attention is given to the possibility of keeping the lamellar organisation along with the elimination of the organic template. [less ▲]

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See detailInvestigation of DyBa2CU3O7-d superconducting domains grown by the infiltration technique starting with small size Dy-211 particles
Mathieu, Jean-Philippe; Koutzarova, T.; Rulmont, André ULg et al

in Superconductor Science and Technology (2005), 18(2 Sp. Iss. SI), 136-141

An infiltration and growth process is here used as an alternative to the classical top-seeded melt-textured growth process for the production of Dy-123 single-domains with finely dispersed small size Dy ... [more ▼]

An infiltration and growth process is here used as an alternative to the classical top-seeded melt-textured growth process for the production of Dy-123 single-domains with finely dispersed small size Dy-211 particles. The starting materials are the 211-particles and a barium and copper rich liquid phase precursor. The infiltration and growth process allows for controlling both the spatial and size distribution of the 211-particles in the final superconducting 123-single-domain. The main parameters (set-ups, maximum processing temperature with respect to the peritectic temperature, nature of reactant, porosity of the 211-preform) of the infiltration and growth process are discussed. Moreover, different processes of chimie douce are shown in order to produce Dy-211 particles with controlled shape and size, particles that can be used as precursors for the infiltration and growth process. [less ▲]

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See detailAnisotropic behaviour in the magnetic field dependence of the low temperature electrical resistance of calcium-doped lanthanum manganate thin films grown by RF magnetron sputtering
Vertruyen, Bénédicte ULg; Dusoulier, Laurent; Fagnard, Jean-François ULg et al

in Journal of Magnetism and Magnetic Materials (2004), 280(2-3), 264-272

We report about the magnetoresistive properties of calcium-doped lanthanum manganate thin films grown by RF magnetron sputtering on single crystalline LaAiO(3) and MgO substrates. Two orientations of the ... [more ▼]

We report about the magnetoresistive properties of calcium-doped lanthanum manganate thin films grown by RF magnetron sputtering on single crystalline LaAiO(3) and MgO substrates. Two orientations of the magnetic field with respect to the electrical current have been studied: (i) magnetic field in the plane of the film and parallel to the electrical current, and (ii) magnetic field perpendicular to the plane of the film. The film grown on LaAlO3 is characterised by an unusual magneto resistive behaviour when the magnetic field is applied perpendicular to the film plane: the appearance of two bumps in the field dependence of the resistance is shown to be related to the occurrence of anisotropic magneto resistive effects in manganate films. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailDetermination of surface composition of alloy nanoparticles and relationships with catalytic activity in Pd-Cu/SiO2 cogelled xerogel catalysts
Lambert, Stéphanie ULg; Heinrichs, Benoît ULg; Brasseur, Alain et al

in Applied Catalysis A : General (2004), 270(1-2), 201-208

The combination of results from carbon monoxide chemisorption, X-ray diffraction, and transmission electron microscopy allowed calculating the surface composition of the palladium-copper nanoparticles in ... [more ▼]

The combination of results from carbon monoxide chemisorption, X-ray diffraction, and transmission electron microscopy allowed calculating the surface composition of the palladium-copper nanoparticles in Pd-Cu/SiO2 cogelled xerogel catalysts. Values obtained indicate a very pronounced surface enrichment with copper. Surface compositions obtained with this method, which combines three different experimental techniques, are in agreement with the literature data previously obtained for surface segregation in Pd-Cu/SiO2 catalysts by other techniques as low energy ion scattering and X-ray photoelectron spectroscopy. While 1,2-dichloroethane hydrodechlorination over pure palladium mainly produces ethane, increasing copper content in bimetallic catalysts results in an increase in ethylene selectivity, to reach 100% in ethylene selectivity for the sample containing 1.4 wt.% of palladium and 3.0 wt.% of copper. (C) 2004 Elsevier B.V. All rights reserved. [less ▲]

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See detailDibarium zirconium tetraoxalate trihydrate
Vertruyen, Bénédicte ULg; Robertz, Bénédicte; Guillaume, Bernard ULg et al

in Acta Crystallographica Section C-Crystal Structure Communications (2004), 60(Pt 6), 233-234

A new mixed barium zirconium oxalate, triaquatetra-mu-oxalato-dibarium(II)zirconium(IV), Ba2Zr(C2O4)(4).3H(2)O or [Ba2Zr(C2O4)(4)(H2O)(3)](n), has been synthesized. The complex is built from eightfold ... [more ▼]

A new mixed barium zirconium oxalate, triaquatetra-mu-oxalato-dibarium(II)zirconium(IV), Ba2Zr(C2O4)(4).3H(2)O or [Ba2Zr(C2O4)(4)(H2O)(3)](n), has been synthesized. The complex is built from eightfold-coordinated Zr atoms and eleven- and sixfold-coordinated Ba atoms, linked by oxalate groups. The Zr atom, the two Ba atoms and one water O atom lie on crystallographic twofold axes, so that each coordination polyhedron has imposed C2 symmetry. Packing in the crystal is also assumed through hydrogen bonds. [less ▲]

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See detailA Microstructural Study of Doped-LaGaO3 (La0.9Sr0.1Ga0.8Mg0.2O2.85) Produced by an Autocombustion from a Gel-like Precursor
Traina, Karl ULg; Pirard, Jean-Paul; Rulmont, André ULg et al

in Bossel, Ulf (Ed.) Sixth European Solid Oxide Fuel Cell Forum - Proceedings (2004, June)

Polycrystalline dense samples of lanthanum gallate doped with strontium and magnesium (La0.9Sr0.1Ga0.8Mg0.2O2.85 or LSGM) was prepared using a novel gel precursor synthesis method. This consists in ... [more ▼]

Polycrystalline dense samples of lanthanum gallate doped with strontium and magnesium (La0.9Sr0.1Ga0.8Mg0.2O2.85 or LSGM) was prepared using a novel gel precursor synthesis method. This consists in preparing a LSGM precursor from a freeze-dried Agar-Agar gel. After the freeze-drying step, the dry residue is put in an oven at 120°C where autocombustion occurred. The as-produced powders are then calcined. Investigations are made to follow both structural and microstructural evolutions from the dry residue to the end product. The effect of the temperature evolution was examined by thermogravimetric analysis, X-ray diffraction, environmental scanning electron microscopy, and specific surface area analysis. Dilatometric curves and density measurements have been also performed on the sintered products. Advantages of this method are the ability to control size distribution and to obtain high density materials without any milling step thus avoiding any contamination coming from the grinding medium. [less ▲]

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See detailPolymer layered silicate/carbon nanotubes nanocomposites: morphological and rheological properties
Peeterbroeck, S.; Alexandre, Michaël ULg; BNagy, J. et al

Poster (2004, May 27)

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See detailEffects of silicon addition on the electrical and magnetic properties of copper-doped (La,Ca)MnO3 compounds
Vertruyen, Bénédicte ULg; Rulmont, André ULg; Cloots, Rudi ULg et al

in Journal of Magnetism and Magnetic Materials (2004), 268(3), 364-373

In this paper we report about the electrical properties of La0.7Ca0.3MnO3 compounds substituted by copper on the manganese site and/or deliberately contaminated by SiO2 in the reactant mixture. Several ... [more ▼]

In this paper we report about the electrical properties of La0.7Ca0.3MnO3 compounds substituted by copper on the manganese site and/or deliberately contaminated by SiO2 in the reactant mixture. Several phenomena have been observed and discussed. SiO2 addition leads to the formation of an apatite-like secondary phase that affects the electrical conduction through the percolation of the charge carriers. On the other hand, depending on the relative amounts of copper and silicon, the temperature dependence of the electrical resistivity can be noticeably modified: our results enable us to compare the effects of crystallographic vacancies on the A and B sites of the perovskite with the influence of the copper ions substituted on the manganese site. The most original result occurs for the compounds with a small ratio Si/Cu, which display double-peaked resistivity vs. temperature curves. (C) 2003 Elsevier B.V. All rights reserved. [less ▲]

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See detailThe contribution of 211 particles to the mechanical reinforcement mechanism of 123 superconducting single domains
Mathieu, Jean-Philippe; Cano, I. G.; Koutzarova, T. et al

in Superconductor Science and Technology (2004), 17(1), 169-174

Hardness and fracture toughness of Dy-123 single domains were studied by Vickers in micro-indentation. A significant anisotropy of the mechanical properties was observed. Hardness tests give higher values ... [more ▼]

Hardness and fracture toughness of Dy-123 single domains were studied by Vickers in micro-indentation. A significant anisotropy of the mechanical properties was observed. Hardness tests give higher values when performed in (001) planes rather than in planes parallel to the c-axis. Moreover, the cracks pattern around the indentation follows preferential orientation in planes parallel to the c-axis whereas a classical 'four-cracks' pattern is observed in the (001) planes. It has been possible to show the crucial role played by the 211 particles in the deviating mechanism of cracks and the relevance of the high homogeneity of 211-particle distribution in the material. [less ▲]

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See detailPreparation of nanosized barium zirconate powder by precipitation in aqueous solution
Boschini, Frédéric ULg; Guillaume, Bernard ULg; Rulmont, André ULg et al

in Key Engineering Materials [=KEM] (2004), 264-268(Part 1-3), 2335-2338

Several ways were explored to synthesize barium zirconate by soft chemistry methods in aqueous solution. In the first method the synthesis of barium zirconate was initiated by urea decomposition, through ... [more ▼]

Several ways were explored to synthesize barium zirconate by soft chemistry methods in aqueous solution. In the first method the synthesis of barium zirconate was initiated by urea decomposition, through an homogeneous precipitation of barium and zirconium salts followed by a "low temperature" thermal treatment. The kinetic of the reaction and the optimum urea/cation ratio have been determined by means of X-ray diffraction and Inductive Coupled Plasma analyses. It has been demonstrated that an amorphous zirconium hydrated oxide starts to precipitate followed by the precipitation of barium carbonate[1]. A calcination at 1200degreesC during 2 hours gives rise to the formation of a pure barium zirconate phase. In the other methods, barium zirconate was synthesized, in one step without any thermal treatments, by precipitation in highly basic aqueous solutions containing barium and zirconium salts. The effect of the hydroxide concentration was discussed in relation to the barium zirconate phase formation, the particles size and the particles size distribution. For each powder, microstructural characterisations have been performed on sintered bodies in order to evaluate the influence of the thermal treatment on the final density. Dilatometric measurements have been also performed in order to quantify the densification process. Important informations were obtained by these techniques, as for example the existence of an internal porosity which severely limits the final density of the material, even if sintering was performed at high temperature. Thus a careful control of the heating profile seems to be necessary in order to produce dense materials. [less ▲]

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See detailac magnetic behavior of large-grain magnetoresistive La0.78Ca0.22Mn0.90Ox materials
Vanderbemden, Philippe ULg; Vertruyen, Bénédicte ULg; Rulmont, André ULg et al

in Physical Review. B (2003), 68(22), 224418

We report a detailed set of ac magnetic measurements carried out on bulk large grain La-Ca-Mn-O samples extracted from a floating zone method-grown rod. Three samples with La0.78Ca0.22Mn0.90Ox ... [more ▼]

We report a detailed set of ac magnetic measurements carried out on bulk large grain La-Ca-Mn-O samples extracted from a floating zone method-grown rod. Three samples with La0.78Ca0.22Mn0.90Ox stoichiometry but differing in their microstructure were investigated by electrical resistivity and ac susceptibility measurements: (i) a single grain sample, (ii) a sample containing two grains, and (iii) a polycrystalline sample. We show that the superimposition of dc magnetic fields during ac magnetic susceptibility measurements is an efficient way for characterizing the magnetic transition of samples with different microstructures. Whereas both single grain and polycrystalline samples display a single susceptibility peak, an additional kink structure is observed in the case of the double grain sample. The temperature dependence of the ac susceptibility measured with superimposed dc magnetic fields is analyzed in the framework of second-order phase transition ideas. The relations between the critical exponents (beta+gamma ~ 1.5, delta ~ 2.5) are found to be close to those of the mean-field model for all samples. This is attributed to the disordering caused by unoccupied Mn sites. ©2003 The American Physical Society. [less ▲]

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See detailStructural evolution of lamellar surfactant-silica hybrids upon calcination
Henrist, Catherine ULg; Cano, I. G.; Rodriguez, M. A. et al

in Composites Science and Technology (2003), 63(8), 1127-1131

A lamellar mesostructured silica was subjected to a progressive heat treatment in order to study its structural evolution and the characteristics of the resulting calcined powder. By combining ... [more ▼]

A lamellar mesostructured silica was subjected to a progressive heat treatment in order to study its structural evolution and the characteristics of the resulting calcined powder. By combining informations from several physical methods, i.e. TG-DTA, XRD, TEM and nitrogen adsorption, it has been possible to evidence the formation of very small particles of silica at a temperature around 450 degreesC, exhibiting a very high value of aspect ratio, consequently to the template loss by combustion. By increasing the temperature above 530 degreesC, the dehydroxylation promotes a decrease in the surface area, followed by the sintering process at higher temperature, which nearly annihilate the surface area of the particles. (C) 2003 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailStudy of the morphology of copper hydroxynitrate nanoplatelets obtained by controlled double jet precipitation and urea hydrolysis
Henrist, Catherine ULg; Traina, Karl ULg; Hubert, Cédric ULg et al

in Journal of Crystal Growth (2003), 254(1-2), 176-187

A copper hydroxynitrate of stoichiometry Cu-2(OH)(3)NO3, analogous to the layered double hydroxide family, was synthesized by the so-called controlled double jet precipitation technique, and by hydrolysis ... [more ▼]

A copper hydroxynitrate of stoichiometry Cu-2(OH)(3)NO3, analogous to the layered double hydroxide family, was synthesized by the so-called controlled double jet precipitation technique, and by hydrolysis of urea in the presence of copper nitrate. Special attention has been focused on the size, morphology and agglomeration tendency of the particles. The aim of this work is to define the optimum precipitation conditions in terms of quality and dispersability of the recovered product. Such platelet-like particles Can be used as anisotropic fillers in nanocomposite materials. Several reaction parameters such as flow and concentration of the reactant solutions, design of the reactor and addition of a growth modifier were studied. (C) 2003 Elsevier -Science B.V. All rights reserved. [less ▲]

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See detailPreparation of BaZrO3 powders by a spray-drying process
Robertz, B.; Boschini, Frédéric ULg; Rulmont, André ULg et al

in Journal of Materials Research (2003), 18(6), 1325-1332

The potential use of barium zirconate for the manufacture of corrosion-resistant substrates emphasizes the need for a simple, inexpensive, and easily scalable process to produce high-quality powders with ... [more ▼]

The potential use of barium zirconate for the manufacture of corrosion-resistant substrates emphasizes the need for a simple, inexpensive, and easily scalable process to produce high-quality powders with well-controlled composition and properties. However, the classical solid-state preparation of barium zirconate leads to an inhomogeneous powder unsuitable for applications in highly corrosive environment. For this paper, the possibility to use the spray-drying technique for the preparation of BaZrO3 powders with a controlled size distribution and morphology was investigated. The influence of the nature and concentration of the precursor solution and the influence of the spray-drying step are discussed on the basis of x-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, and dilatometric measurements. [less ▲]

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See detailPolymer/layered silicate nanocomposites by combined intercalative polymerization and melt intercalation: a masterbatch process
Lepoittevin, Bénédicte; Pantoustier, Nadège; Devalckenaere, Myriam et al

in Polymer (2003), 44(7), 2033-2040

Poly(ε-caprolactone) (PCL) and poly(vinyl chloride) (PVC) layered silicate nanocomposites were prepared by combination of intercalative polymerization and melt intercalation. In a first step, high clay ... [more ▼]

Poly(ε-caprolactone) (PCL) and poly(vinyl chloride) (PVC) layered silicate nanocomposites were prepared by combination of intercalative polymerization and melt intercalation. In a first step, high clay content PCL nanocomposites were prepared by in situ polymerization of -caprolactone intercalated between selected organo-modified silicate layers. The polymerization was catalyzed with dibutyltin dimethoxide in the presence of montmorillonites, the surface of which were previously exchanged with (functionalized) long alkyl chains ammonium cations. Then, these highly filled PCL nanocomposites were added as masterbatches in commercial PCL and PVC by melt blending. The intercalation of PCL chains within the silicate layers by in situ polymerization proved to be very efficient, leading to the formation of intercalated and/or exfoliated structures depending on the organo-clay. These masterbatches were readily dispersed into the molten PCL and PVC matrices yielding intercalated/exfoliated layered silicate nanocomposites which could not be obtained by melt blending the matrix directly with the same organo-modified clays. The formation of nanocomposites was assessed both by X-ray diffraction and transmission electronic microscopy. Interestingly, this so-called 'masterbatch' two-step process allowed for preparing PCL nanocomposites even with non-modified natural clay, i.e. sodium montmorillonite, which showed a material stiffness much higher than the corresponding microcomposites recovered by direct melt intercalation. The thermal stability of PCL nanocomposites as a function of clay content was investigated by thermogravimetry (TGA). [less ▲]

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See detailMorphological study of magnesium hydroxide nanoparticles precipitated in dilute aqueous solution
Henrist, Catherine ULg; Mathieu, J. P.; Vogels, C. et al

in Journal of Crystal Growth (2003), 249(1-2), 321-330

Among other applications, magnesium hydroxide is commonly used as a flame-retardant filler in composite materials, as well as a precursor for magnesium oxide refractory ceramic. The microstructure of the ... [more ▼]

Among other applications, magnesium hydroxide is commonly used as a flame-retardant filler in composite materials, as well as a precursor for magnesium oxide refractory ceramic. The microstructure of the powder is of prime importance in both technical applications. The influence of synthesis parameters on the morphological characteristics of magnesium hydroxide nanoparticles precipitated in dilute aqueous medium was studied. Several parameters were envisaged such as chemical nature of the base precipitant, type of counter-ion, temperature and hydrothermal treatment. Special attention was given to the obtaining of platelet-shaped, nanometric and de-agglomerated powders. The powders were characterized in terms of particle size distribution, crystal habits, morphology and ability to be redispersed in water. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), nitrogen adsorption and laser diffusion analyses were used for this purpose. (C) 2002 Elsevier Science B.V. All rights reserved. [less ▲]

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See detailNew nanocomposite materials based on plasticized poly(L-lactide) and organo-modified montmorillonites: thermal and morphological study
Paul, Marie-Amélie; Degée, Philippe; Henrist, Catherine ULg et al

in Polymer (2003), 44(2), 443-450

Plasticized poly(L-lactide) (PLA) based nanocomposites were prepared by melt blending of the matrix with 20 wt% of poly(ethyleneglycol) 1000 (PEG 1000) and different amounts of montmorillonite, organo ... [more ▼]

Plasticized poly(L-lactide) (PLA) based nanocomposites were prepared by melt blending of the matrix with 20 wt% of poly(ethyleneglycol) 1000 (PEG 1000) and different amounts of montmorillonite, organo-modified or not. The intercalation of the polymer chains between the aluminosilicates layers and morphological structure of the filled PLAs were analysed by wide-angle X-ray scattering (WAXS). Thermogravimetric analyses (TGA) and differential scanning calorimetry (DSC) were performed to study the thermal behaviour of the prepared composites. At constant filler level, it appears that from all the clays studied, the montmorillonite organo-modified by bis-(2-hydroxyethyl)methyl (hydrogenated tallowalkyl) ammonium cations brings the greater effect in terms of thermal stability. Increasing the amount of clay allows to delay the onset of thermal degradation of the plasticized polymer matrix. It was also pointed out, by WAXS and DSC analyses, that it exists a real competition between PEG 1000 and PLA for the intercalation into the interlayer spacing of the clay. (C) 2002 Elsevier Science Ltd. All rights reserved. [less ▲]

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See detailSynthesis and characterization of new inorganic polymeric composites based on kaolin or white clay and on ground-granulated blast furnace slag
Lecomte, I.; Liégeois, Monique ULg; Rulmont, André ULg et al

in Journal of Materials Research (2003), 18(11), 2571-2579

Alkali activation of dehydroxylated kaolin or clay yielded high-strength polymeric materials, so-called geopolymers. They were synthesized by mixing the aluminosilicate with solutions of sodium ... [more ▼]

Alkali activation of dehydroxylated kaolin or clay yielded high-strength polymeric materials, so-called geopolymers. They were synthesized by mixing the aluminosilicate with solutions of sodium metasilicate and KOH followed by adding 45 wt.% of ground-granulated blast furnace slag. The influence of the aluminosilicate source, its activation temperature, and the order of mixing raw materials were studied on the workability of the blending paste, the microstructure, and the Vickers hardness of the geopolymer samples. The polymeric material is completely amorphous according to x-ray diffraction. Solid-state 27Al and 29Si magic-angle-spinning nuclear magnetic resonance showed that the geopolymer consists of AlO 4 and SiO 4 tetrahedra linked together through a polymeric network constituted by branched entities SiQ 4(4Al) and SiQ 4(3Al), but also by less-polymerized silicates SiQ 1 and SiQ 2. Scanning electron microscopy showed a homogeneous polymeric gel matrix containing unreacted slag (and quartz) grains; thermogravimetric analysis and differential scanning calorimetry exhibited a high content of water and an elevated melting point (1260 °C). Vickers hardness values are in the range of 200 MPa. [less ▲]

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See detailIntercalative polymerization of cyclic esters in layered silicates : thermal vs. catalytic activation
Pantoustier, Nadège; Alexandre, Michaël ULg; Degée, Philippe et al

in Composite Interfaces (2003), 10(4-5), 423-433

Poly(ε-caprolactone) layered silicate nanocomposites were synthesized by in situ inter-calative ring-opening polymerization (ROP) of ε-caprolactone. The polymerization was promoted by thermal or catalytic ... [more ▼]

Poly(ε-caprolactone) layered silicate nanocomposites were synthesized by in situ inter-calative ring-opening polymerization (ROP) of ε-caprolactone. The polymerization was promoted by thermal or catalytic initiation starting from either non-modified natural sodium-montmorillonite (MMT-Na) or montmorillonite modified by different ammonium cations bearing either non-functional alkyl chains or chains terminated by carboxylic acid or hydroxyl functions. The resulting compositions were analyzed by small-angle X-ray diffraction and transmission electron microscopy. The clay dispersion depended on the structure of the alkyl ammonium. Exfoliated nanocomposites were formed when hydroxyl-containing alkyl-ammonium was used; otherwise, partially intercalated/partially exfoliated structures were observed. Moreover, caving to the inherent catalytic properties of the montmo-rillomte surface, it was also possible to prepare intercalated nanocomposites by in situ polymerization of ε-caprolactone in presence of non-modified montmorillonite-Na (MMT-Na) without any added catalyst. [less ▲]

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