Influence of extrusion conditions on the rheological behavior of nuclear bituminized waste products / M. Mouazen in INTERNATIONAL POLYMER PROCESSING, Vol. XXVI, N° 5 (11/2011)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVI, N° 5 (11/2011) . - p. 569-579 Titre : Influence of extrusion conditions on the rheological behavior of nuclear bituminized waste products Type de document : texte imprimé Auteurs : M. Mouazen, Auteur ; Arnaud Poulesquen, Auteur ; Bruno Vergnes, Auteur Année de publication : 2011 Article en page(s) : p. 569-579 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bitume -- Extrusion Déchets radioactifs -- Bituminisation Dispersions et suspensions Extrudeuse bi-vis Rhéologie Index. décimale : 668.4 Plastiques, vinyles Résumé : In France, bitumen has been used since four decades as a container material for low/intermediate activity and long lifetime radionuclides. Industrial Bituminized Waste Products (BWP) are produced by continuous extrusion of 60 wt.% bitumen and 40 wt.% salts, in which a very small fraction is radioactive. These incorporated salts are, in majority, of two types: soluble or insoluble. During storage, the organic matrix subjected to irradiation produces gases, which can give rise to BWP swelling in the container and then to a possible overflow. The extent of gas production is directly linked to the degree of dispersion of the salts into the bitumen matrix. To quantify this dispersion, the effect of extrusion operating conditions, such as feed rate and screw speed, have been studied using a laboratory scale co-rotating twin screw extruder. BWP rheological characterization shows the development of a pseudo-solid plateau at low frequency and a change in the linear viscoelastic domain when screw speed and feed rate are varied, indicating a modification of the dispersion state. Samples characterization with environmental scanning electron microscopy (ESEM) confirms in the case of insoluble and soluble salts a change in the number of agglomerates, accompanied by an improvement of the dispersion at high screw speed but less remarkable with the feed rate. A Carreau-Yasuda law with a yield stress is proposed to describe the rheological behaviour of these materials. The effects of volume fraction and maximum volume fraction on viscosity are described using a Krieger-Dougherty equation. DOI : 10.3139/217.2496 En ligne : https://drive.google.com/file/d/1oMMAXCU6RA7tfIZGRSAOSYBVeKwkXt0Z/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12479 [article]

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Optimization of processing conditions for polymer twin-screw extrusion / A. Gaspar-Cunha in INTERNATIONAL POLYMER PROCESSING, Vol. XVII, N° 3 (09/2002)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVII, N° 3 (09/2002) . - p. 201-213 Titre : Optimization of processing conditions for polymer twin-screw extrusion Type de document : texte imprimé Auteurs : A. Gaspar-Cunha, Auteur ; Arnaud Poulesquen, Auteur ; Bruno Vergnes ; Jose A. Covas, Auteur Année de publication : 2002 Article en page(s) : p. 201-213 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The problem of setting the best operating conditions of a co-rotating twin-screw extruder is solved using an optimization approach based on Genetic Algorithms. Two possibilities are considered: i) the maximization of an objective function; ii) the simultaneous optimization of the individual criteria and the use of Pareto plots. The flow conditions inside the machine are simulated using the Ludovic© software. Various practical case studies are discussed, among them a reactive extrusion application. Generally, the methodology is sensitive to the influence of the main process criteria and provides solutions that are apparently sound. Note de contenu : - Modeling of twin-screw extrusion - Available software - Computional example - Optimization methodology - Materials and equipment - Case studies - RESULTS AND DISCUSSION : Processing - Reactive extrusion DOI : 10.3139/217.1701 En ligne : https://drive.google.com/file/d/1boEdn2ELpCMWSlEjO4LZNOWKBD6tRlo_/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15995 [article]

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Polymerization of ε-caprolactone in a twin screw extruder / Arnaud Poulesquen in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 1 (03/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 1 (03/2001) . - p. 31-38 Titre : Polymerization of ε-caprolactone in a twin screw extruder : Experimental study and modelling Type de document : texte imprimé Auteurs : Arnaud Poulesquen, Auteur ; Bruno Vergnes, Auteur ; Philippe Cassagnau, Auteur ; J. Gimenez, Auteur ; A. Michel, Auteur Année de publication : 2001 Article en page(s) : p. 31-38 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The purpose of this work is to model the bulk polymerization of ε-caprolactone in a corotating twin screw extruder. Starting from kinetic data and rheological laws previously defined, we use a twin screw flow modelling software to calculate the progress of the polymerization along the extruder. Experiments are performed to assess the influence of processing conditions (feed rate, screw speed, barrel temperature, initiator concentration) and to validate the model. They put in evidence the control of the polymerization process by temperature and the residence time in the extruder. It is shown that a good correlation between theoretical and experimental results can only be obtained if accurate kinetic and rheological data are used in the m DOI : 10.3139/217.1626 En ligne : https://drive.google.com/file/d/14-m_LXLBV04m_d0S3m64_1o_JG1tMrRY/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15882 [article]

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Visualisation and analysis of the flow along the kneading block of a twin-screw extruder / Olga. S. Carneiro in INTERNATIONAL POLYMER PROCESSING, Vol. XVII, N° 4 (12/2002)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVII, N° 4 (12/2002) . - p. 301-308 Titre : Visualisation and analysis of the flow along the kneading block of a twin-screw extruder Type de document : texte imprimé Auteurs : Olga. S. Carneiro, Auteur ; Arnaud Poulesquen, Auteur ; Bruno Vergnes, Auteur ; Jose A. Covas, Auteur Année de publication : 2002 Article en page(s) : p. 301-308 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The flow of a silicone oil of high viscosity along a block of staggered kneading discs of a co-rotating twin screw extruder was investigated with the use of an acrylic transparent barrel. A digital video camera recorded the flow path of a red dye, dispersed in the silicone oil, along the screws and in the intermeshing zone. Different geometrical configurations were studied, namely various staggering angles (+30°, 90° and -30°) and thicknesses (7.5, 15.0 and 22.5 mm) of kneading blocks. The effects of these geometrical parameters on the pressure generation and filling ratio were investigated. It was observed that, even for negative staggering, the filling ratio of the kneading block was lower than one. Based upon these experiments, analytical expressions describing the filling ratio as function of geometry (staggering angle, thickness and number of discs) and operating conditions (feed rate and screw speed) were derived. Note de contenu : - MATERIALS AND EXPERIMENTAL PROTOCOL - EXPERIMENTAL RESULTS : Staggering angle α'=-30° - Staggering angle α'=+30° - Staggering angle α'=90° - CALCULATION OF THE FILLING RATIO : Negative staggering angle - Neutral staggering angle DOI : 10.3139/217.1708 En ligne : https://drive.google.com/file/d/1qhA7esmiVYtH1a-jB7TU6I2laXgA8QAk/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16018 [article]

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