References of "Pirard, René"
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See detailTextural properties and thermal stability of silica-zirconia aerogels
Pirard, René ULg; Bonhomme, Damien; Kolibos, Sofia et al

in Journal of Sol-Gel Science and Technology (1997), 8

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See detailSynthesis and characterization of monodisperse spherical zirconia particles
Van Cantfort, Olivier; Michaux, Bernard; Pirard, René ULg et al

in Journal of Sol-Gel Science and Technology (1997), 8

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See detailSynthesis of resorcinol-formaldehyde aeroels by the freeze-drying methods
Mathieu, Bernard; Michaux, Bernard; Pirard, René ULg et al

in Annales de Chimie Science des Materiaux (1997), 22

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See detailSynthesis and characterization of porous silica-alumina xerogels
VanCantfort, Olivier; Abid, A.; Michaux, Bernard et al

in Journal of Sol-Gel Science and Technology (1997), 8

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See detailMercury porosimetry applied to low density xerogels
Pirard, René ULg; Heinrichs, Benoît ULg; Van Cantfort, Olivier et al

Poster (1997)

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See detailAerogel compression theoretical analysis
Pirard, René ULg; Pirard, Jean-Paul ULg

in Journal of Non-Crystalline Solids (1997), 212(2-3), 262-267

Several authors have empirically shown that, in aerogels, a power law exists between the mechanical moduli and the bulk density. An exponent value can be determined from mercury porosimetry curves. The ... [more ▼]

Several authors have empirically shown that, in aerogels, a power law exists between the mechanical moduli and the bulk density. An exponent value can be determined from mercury porosimetry curves. The shrinkage of aerogels under mercury pressure follows a buckling mechanism which links the pore size to the exerted pressure. The present study relates the exponent to the pore volume distribution which can be described by a hierarchical model valid in a large range of pore size, so a physical meaning is given to the exponent. [less ▲]

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See detailFreeze-dried resorcinol-formaldehyde gels
Blacher, Silvia ULg; Pirard, René ULg; Pirard, Jean-Paul ULg et al

in Journal of Non-Crystalline Solids (1997), 212(2-3), 250-261

The texture of resorcinol-formaldehyde gels, previously synthesized by Pekala et al. [1-6], but dried by freeze-drying was studied. The freeze-dried gels present a complex porous structure from nanometer ... [more ▼]

The texture of resorcinol-formaldehyde gels, previously synthesized by Pekala et al. [1-6], but dried by freeze-drying was studied. The freeze-dried gels present a complex porous structure from nanometer to micrometer length-scale. Taking a standard freezing rate, we study in detail the influence of the molar ratio resorcinol/catalyst on the texture, This molar ratio is one of the parameters under consideration which can lead to a tailoring of the dried gel texture in order to develop adsorbents or catalyst supports of controlled porosity. Characterization methods include nitrogen adsorption-desorption (including the classical and the fractal interpretations), mercury porosimetry, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and small angle X-ray scattering (SAXS). [less ▲]

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See detailTransition metal aerogel-supported catalyst
Heinrichs, Benoît ULg; Pirard, Jean-Paul ULg; Pirard, René ULg

Patent (1996)

A process for preparing a supported catalyst comprising a transition metal selected from palladium, platinum, nickel, cobalt or copper on an aerogel support, which includes the steps of providing a ... [more ▼]

A process for preparing a supported catalyst comprising a transition metal selected from palladium, platinum, nickel, cobalt or copper on an aerogel support, which includes the steps of providing a mixture containing an alkoxide precursor of the aerogel, a chelate complex of the transition metal with a chelating agent having Si(OR)3 anchor groups, and an organic solvent in which the chelate complex is soluble; hydrolyzing the mixture by admixing it with water to form a gel; and converting the gel under supercritical conditions into the transition metal aerogel-supported catalyst. The supported catalyst has an especially homogeneous distribution of the metal component and is suitable, for example, for use as a hydrogenation catalyst. [less ▲]

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See detailAC Properties of Carbon Black Filled Polymer Blends
Brouers, F.; Royen, I.; Blacher, Silvia ULg et al

in Materials Research Society Symposium Proceedings (1996), 411

The macroscopic electrical properties of carbon black filled polyethylene (PE)/poly-styrene (PS) blends depend strongly on the selective localization of carbon black particles in one of the phases of the ... [more ▼]

The macroscopic electrical properties of carbon black filled polyethylene (PE)/poly-styrene (PS) blends depend strongly on the selective localization of carbon black particles in one of the phases of the polyblend. The electrical and dielectric properties of these materials can be understood in the framework of the double percolation theory. It appears that in the vicinity of the carbon black percolation threshold, the electrical conduction is dominated by tunneling. The recent theory of Brouers and Sarychev which includes quantum tunneling in the percolation scaling laws provides the basis for a discussion of the observed frequency dependence of the conductivity and the dielectric constant in the range 10-3 –10° Hz and its relation to the blend morphology. [less ▲]

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See detailSynthesis and characterization of porous silica-alumina xerogels
Van Cantfort, O.; Abid, A.; Michaux, B. et al

Conference (1995)

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