References of "Devaux, Jacques"
     in
Bookmark and Share    
Full Text
Peer Reviewed
See detailInfluence of steam explosion on physico-chemical properties and hydrolysis rate of pure cellulose fibers
Jacquet, Nicolas ULg; Vanderghem, Caroline ULg; Danthine, Sabine ULg et al

in Bioresource Technology (2012), 121(221-227),

The aim of the present study is to compare the effect of different steam explosion treatments on physicochemical properties and hydrolysis rate of a pure bleached cellulose. The results showed that ... [more ▼]

The aim of the present study is to compare the effect of different steam explosion treatments on physicochemical properties and hydrolysis rate of a pure bleached cellulose. The results showed that moderate steam explosion treatments (severity factor below 5.2) did not improve the enzymatic hydrolysis rate of the cellulose fibers. The characterization of the obtained samples showed an increase of the cellulose accessibility coupled with an increase of the overall crystallinity of the substrate. In these conditions, the higher accessibility is counterbalanced by the increased crystallinity. Indeed, a greater proportion of the substrat is accessible by only a fraction of the enzymatic complex (exo-glucanases) activities. When the severity factor reached 5.2, a decrease of the cellulose enzymatic hydrolysis rate was observed. In this case, TGA analysis showed an increase of the char level at the end of the pyrolysis which traduced an important thermal degradation of the samples. The thermal degradation of cellulose lead to an important change in substrate composition, which induced a decrease of the cellulose ratio available for hydrolysis and caused a decrease of the hydrolysis yields. [less ▲]

Detailed reference viewed: 64 (20 ULg)
Full Text
Peer Reviewed
See detailInfluence des traitements de steam explosion sur la dégradation thermique des fibres de cellulose
Jacquet, Nicolas ULg; Quievy; Vanderghem, Caroline ULg et al

Poster (2011, December)

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités ... [more ▼]

La présente étude a pour but d’identifier l’impact de différents traitements de steam explosion sur les propriétés de dégradation thermique des fibres de cellulose. Dans un premier temps, les intensités des traitements appliqués ont été définies sur base d’un facteur de sévérité (SF), établi par une corrélation entre le temps de séjour et la température du process. Les résultats obtenus montrent que la dégradation thermique des fibres de cellulose reste limitée lorsque la valeur du facteur de sévérité est inférieure à 4.0. Aux intensités supérieures, le dosage des produits de dégradation montre une croissante importante des concentrations en hydroxyméthylfurfurals (5-HMF) dans les phases liquides issues des différents traitements. Lorsque la valeur du facteur de sévérité dépasse 5.2, les analyses TGA indiquent que l’augmentation des produits de dégradation est couplée à une croissance importante du taux de résidus carbonés, indiquant une forte dégradation thermique de la cellulose [less ▲]

Detailed reference viewed: 61 (26 ULg)
Full Text
Peer Reviewed
See detailInfluence of steam explosion on the thermal stability of cellulose fibres
Jacquet, Nicolas ULg; Quievy, Nicolas; Vanderghem, Caroline ULg et al

in Polymer Degradation & Stability (2011), 96

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which ... [more ▼]

The aim of the present study was to compare the effect of different steam explosion treatments on the thermal degradation of a bleached cellulose. The intensity of a steam explosion treatment, which allows breakdown of the structural lignocellulosic material was determined by a correlation between time and temperature of the process. Results of this study showed that thermal degradation of cellulose fibres was limited when the severity factor applied was below 4.0. For higher intensities, determination of the degradation products in the water-soluble extract showed an important increase of the 5-hydroxymethyl-furfural concentration with the temperature. When the severity factor reached 5.2., TGA analysis showed that the increase of degradation products was coupled to an increase of the char level meaning a strong degradation of the cellulose. dTGA behaviour also showed that thermal stability of the steam explosion samples decreased with the intensity of the treatment. To conclude, a theoretical diagram predicting the degradation of the cellulose during the steam explosion treatment was established. [less ▲]

Detailed reference viewed: 86 (39 ULg)
Full Text
See detailInfluence of steam explosion and thermal degradation of cellulose
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

Poster (2010, August 20)

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have ... [more ▼]

The aim of the present work is to compare the effect of different steam explosion pretreatments on the thermal degradation of a bleached cellulose where components like hemicelluloses and lignin have already been removed by acid and alkaline treatments. The results of this study show that thermal degradation of cellulose fibres, studied by TGA, is still limited for a temperature process below 240 °C. However, derivative TGA show that thermal stability of cellulose obtained by these conditions decreases with the increase of temperature. For temperatures above 250°C, char level is higher at the end of the pyrolysis. According to the literature, the increase of the char level is correlated to an increase of the degradation product1. Determination of the degradation products in the liquor obtained after the pretreatment show an important increase of furfural and 5-hydroxymethylfurfural concentration with the temperature in agreement with the increase of the char level. These results confirm the important degradation of the cellulose fibres. [less ▲]

Detailed reference viewed: 33 (7 ULg)
Full Text
See detailSteam explosion pretreatment and thermal degradation of cellulose fibers
Jacquet, Nicolas ULg; Quiévy, Nicolas; Vanderghem, Caroline ULg et al

Conference (2010, August 20)

Detailed reference viewed: 19 (8 ULg)
Full Text
Peer Reviewed
See detailMorphology and properties of SAN-clay nanocomposites prepared principally by water-assisted extrusion
Mainil, Michaël; Urbanczyk, Laetitia ULg; Calberg, Cédric ULg et al

in Polymer Engineering & Science (2010), 50(1), 10-21

An efficient extrusion process involving the injection of water while processing was used to prepare poly(styrene-co-acrylonitrile) (SAN) / clay nanocomposites with a high degree of nanoclay delamination ... [more ▼]

An efficient extrusion process involving the injection of water while processing was used to prepare poly(styrene-co-acrylonitrile) (SAN) / clay nanocomposites with a high degree of nanoclay delamination. The usefulness of water-assisted extrusion is highlighted here, in comparison with classical extrusion and roll mill processes. Cloisite® 30B (C30B), a montmorillonite clay organomodified with alkylammonium cations bearing 2-hydroxyethyl chains, and pristine montmorillonite were melt blended with SAN (25wt% AN) in a semi-industrial scale extruder specially designed to allow water injection. XRD analysis, visual and TEM observations were used to evaluate the quality of clay dispersion. The relationship between the nanocomposite morphology and its mechanical and thermal properties was then investigated. The superiority of the SAN/C30B nanocomposite extruded with water has been evidenced by cone calorimetry tests and thermogravimetric measurements (TGA). These analyses showed a substantial improvement of the fire behavior and the thermal properties, while a 20% increase of the Young modulus was recorded. [less ▲]

Detailed reference viewed: 119 (7 ULg)
Full Text
Peer Reviewed
See detailAnionic synthesis of cyclic anhydride end-capped poly(methyl methacrylate)
Fallais, Isabelle; Pantoustier, Nadège; Devaux, Jacques et al

in Polymer (2000), 41(14), 5535-5539

This paper reports on the anionic synthesis of poly(methyl methacrylate) chains end-capped by cyclic anhydride. The method is based on the chemical derivatization of a precursor tert-butyl diester end ... [more ▼]

This paper reports on the anionic synthesis of poly(methyl methacrylate) chains end-capped by cyclic anhydride. The method is based on the chemical derivatization of a precursor tert-butyl diester end-group. Compared to the thermal modification, which was previously used, this method allows intermolecular coupling and polymer degradation to be avoided. But up to now, the final anhydride content remains moderate and has still to be improved. [less ▲]

Detailed reference viewed: 29 (1 ULg)
Full Text
Peer Reviewed
See detailEnd-capping of polystyrene by aliphatic primary amine by derivatization of precursor hydroxyl end group
Fallais, Isabelle; Devaux, Jacques; Jérôme, Robert ULg

in Journal of Polymer Science. Part A, Polymer Chemistry (2000), 38(9), 1618-1629

A new and very efficient route for the synthesis of aliphatic primary amine terminated polystyrene (PS) is reported. In contrast to most known methods, only traditional commercially available reagents are ... [more ▼]

A new and very efficient route for the synthesis of aliphatic primary amine terminated polystyrene (PS) is reported. In contrast to most known methods, only traditional commercially available reagents are used. PS is synthesized by anionic polymerization with a lithium counter ion and the living chains are end-capped by a hydroxyl group upon addition of ethylene oxide followed by protonation. The -hydroxyl end group is tosylated and the tosylate is then reacted with sodium azide. The azide terminal group is finally reduced into primary amine. The different steps of functionalization have been fully characterized by SEC, ToF-SIMS, FTIR, and 1H NMR. The amine content (= 98%) has been determined by acid-base titration with perchloric acid. It clearly shows the efficiency of the synthetic method reported in this article although it is a multistep method. [less ▲]

Detailed reference viewed: 70 (1 ULg)
Full Text
Peer Reviewed
See detailCoupling of α,ω-dichloropoly (methylphenylsilane) and living poly (styryllithium). Study of the coupling reaction
Demoustier-Champagne, Sophie; Canivet, I.; Devaux, Jacques et al

in Journal of Polymer Science. Part A, Polymer Chemistry (1997), 35(10), 1939-1948

Both di- and triblock copolymers consisting of polystyrene (PS) in conjunction with poly(methylphenylsilane) (PMPS) have been successfully prepared by coupling of ,-dichloro-PMPS with poly(styryllithium ... [more ▼]

Both di- and triblock copolymers consisting of polystyrene (PS) in conjunction with poly(methylphenylsilane) (PMPS) have been successfully prepared by coupling of ,-dichloro-PMPS with poly(styryllithium). The study of this reaction has shown a sudden limitation of the coupling yield, which however depends on the PS block length. Both the polymer concentration and the solvent have also an effect on the coupling reaction. Morphology of the PS-PMPS block copolymers has been observed by transmission electron microscopy. Very complex morphologies have been reported more likely as the result of the competition between the phase separation induced by PS and PMPS immiscibility and the tendency of PMPS to form ordered structures. [less ▲]

Detailed reference viewed: 11 (1 ULg)