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Auteur Jose A. Covas
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Institute for Polymers and Composites/I3N, University of Minho, Guimarà es, Portugal
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Analysis of the morphological development of PBT/ABS blends during the twin screw extrusion and injection molding processes / E. N. Ito in INTERNATIONAL POLYMER PROCESSING, Vol. XVIII, N° 4 (12/2003)
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Titre : Analysis of the morphological development of PBT/ABS blends during the twin screw extrusion and injection molding processes Type de document : texte imprimé Auteurs : E. N. Ito, Auteur ; L. A. Pessan, Auteur ; Jose A. Covas, Auteur ; E. Hage, Auteur Année de publication : 2003 Article en page(s) : p. 376 - 381 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Molding - The aim of this work was to observe the development of the phase morphology of the PBT/ABS blends during their extrusion mixing and injection molding steps. The evolution of the blend morphology during the mixing stage was analyzed using a specially designed co-rotational twin-screw extruder with a collecting device located along the barrel. Blend samples were collected inline along the length of the extruder barrel during the blending process. Samples obtained from the extruded pellets and from injection molded specimens were also used to observe the blend morphology. All the samples were observed by transmission electron microscopy (TEM). They were prepared by cryo-ultramicrotomy and the rubbery phase of the ABS contained in the blends was stained with osmium tetroxide (OsO4).
A special function was established and is proposed to analyze the blend morphology trends through image analysis. In binary blends, the ABS phase showed better dispersion after the mixture passed through the extruder die. However, a coalescence phenomenon was observed during the next molding step. Compatibilized PBT/ABS blends showed better dispersion than binary blends, even after injection molding. The special function used to quantify the dispersion throughout the mixing and molding steps showed an excellent performance.Note de contenu : - MATERIALS AND METHODS : Materials - Equipment - Preparation Methods to Observe Phase Morphology
- RESULTS AND DISCUSSION : Image Analyses - Morphological DevelopmentDOI : 10.3139/217.1780 En ligne : https://drive.google.com/file/d/1wyJ5zIXbkY4E7VZvZLpgAFI4VaeUlDLd/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15821
in INTERNATIONAL POLYMER PROCESSING > Vol. XVIII, N° 4 (12/2003) . - p. 376 - 381[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 001026 - Périodique Bibliothèque principale Documentaires Disponible Bi-axially oriented blown film technology / Olga. S. Carneiro in INTERNATIONAL POLYMER PROCESSING, Vol. XXVII, N° 3 (07/2012)
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Titre : Bi-axially oriented blown film technology : searching for suitable polymers and processing conditions Type de document : texte imprimé Auteurs : Olga. S. Carneiro, Auteur ; Jose A. Covas, Auteur ; C. Domingues, Auteur Année de publication : 2012 Article en page(s) : p. 348-357 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Films plastiques
Matières plastiques -- Extrusion
Matières plastiques -- Moulage par soufflage
Polyéthylène basse densité
Polyéthylène basse densité linéaire
RhéologieIndex. décimale : 668.4 Plastiques, vinyles Résumé : A set of commercial polyethylenes (three LDPE and three LLDPE) was rheological characterized and processed in a laboratory double bubble extrusion line with the purpose of investigating: i) whether their relative processability could be predicted in the laboratory and ii) the effect of operating and machine variables on processability. Oscillatory shear and extensional measurements were able to differentiate the various materials, who also behaved quite differently upon processing. Those with a stronger shear thinning behaviour, higher elasticity and higher melt strength were the most suited to the process. Bubble stability and thickness uniformity were assumed as the main requirements for processability. The former was estimated by monitoring the time required to stabilize the bubble and examining any variation/oscillation in size/shape. Bubble stability depends on the interaction between various parameters, the most relevant being those related with the film cooling stage, namely the axial position of the air rings, the air flow rate and air velocity. The study was preceded by an assessment of the performance of the re-heating oven and die/calibration/centring, as these parameters could also narrow the practical operating window. DOI : 10.3139/217.2538 En ligne : https://drive.google.com/file/d/1vmDHZ82pkVX1zGGfuPziStB4r2smFuX0/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15581
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Code-barres Cote Support Localisation Section Disponibilité 13995 - Périodique Bibliothèque principale Documentaires Disponible Direct method for deconvoluting two residence time distribution curves / S. V. Canevarolo in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 4 (12/2001)
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Titre : Direct method for deconvoluting two residence time distribution curves Type de document : texte imprimé Auteurs : S. V. Canevarolo, Auteur ; T. J. A Mélo, Auteur ; Jose A. Covas, Auteur ; Olga. S. Carneiro, Auteur Année de publication : 2001 Article en page(s) : p. 334-340 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Mixing and screw extrusion - A pair of related Residence Time Distribution (RTD) curves obtained experimentally during extrusion, are deconvoluted using a methodology based on the concept of equivalent residence times. Two points of two RTD curves are equivalent when the same percentage of tracer has exited the system. The time scale of the deconvoluted curve is obtained by subtracting the two equivalent time values of the available RTD curves. The method was tested using simulated pulse-shaped RTD curves and also carrying out measurements on a twin screw extruder. Despite the experimental errors involved, the two tests seem to demonstrate the usefulness of the approach. Note de contenu : - The deconvolution method
- Convolution of two partial curvesDOI : 10.3139/217.1660 En ligne : https://drive.google.com/file/d/1IC09HWbybhci3ASS0yZRCUpsy7dvUZF1/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15917
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Code-barres Cote Support Localisation Section Disponibilité 001018 - Périodique Bibliothèque principale Documentaires Disponible Dynamics of filler size and spatial distribution in a plasticating single screw extruder – modeling and experimental observations / N. Domingues in INTERNATIONAL POLYMER PROCESSING, Vol. XXV, N° 3 (07/2010)
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Titre : Dynamics of filler size and spatial distribution in a plasticating single screw extruder – modeling and experimental observations Type de document : texte imprimé Auteurs : N. Domingues, Auteur ; A. Gaspar-Cunha, Auteur ; Jose A. Covas, Auteur ; M. Camesasca, Auteur ; M. Kaufman, Auteur ; Ica Manas-Zloczower, Auteur Année de publication : 2010 Article en page(s) : p. 188-198 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Extrusion (mécanique)
Matières plastiques -- Extrusion:Polymères -- Extrusion
Simulation par ordinateur
Vis d'extrusionTags : 'Vis d'extrusion' 'Distribution spatiale' 'Dynamique de dispersion' 'Modélisation par ordinateur' Index. décimale : 668.9 Polymères Résumé : A model of agglomerate break-up, incorporating both rupture and erosion, is employed to predict the dynamics of filler size distribution in a plasticating single screw extruder. Filler spatial distribution along the extruder length was also ascertained and direct comparison of experimental and computational data proved to be satisfactory. The method was also used to investigate the effect of material properties, operating conditions and extruder geometry on the dynamics of agglomerate dispersion along a single screw extruder. Generally, dispersion levels were primarily governed by the magnitude of the hydrodynamic stresses developed in the extruder and the residence time in the melt. DOI : 10.3139/217.2319 En ligne : https://drive.google.com/file/d/1XmHHPKoqwVuve8PTbeMo4KMiViOsJWXK/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=9733
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Code-barres Cote Support Localisation Section Disponibilité 012302 - Périodique Bibliothèque principale Documentaires Disponible Extrusion scale-up : An optimization-based methodology / Jose A. Covas in INTERNATIONAL POLYMER PROCESSING, Vol. XXIV, N° 1 (03/2009)
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Titre : Extrusion scale-up : An optimization-based methodology Type de document : texte imprimé Auteurs : Jose A. Covas, Auteur ; A. Gaspar-Cunha, Auteur Année de publication : 2009 Article en page(s) : p. 67-82 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Extrusion Index. décimale : 668.4 Plastiques, vinyles Résumé : Given a reference extruder with a certain geometry and operating point, the aim of scale-up is to define the geometry and operating conditions of a target extruder (generally of significantly different size) in order to subject the material being processed to the same flow and heat transfer conditions, thus yielding products with the same characteristics. Since existing scale-up rules are crude, as they usually consider a single performance measure and produce unsatisfactory results, this work approaches scale-up as a multi-criteria optimization problem, where the aim is to define the geometry/operating conditions of the target extruder that minimize the differences between the values of various performance criteria for the reference and target extruders. Some case studies are discussed involving individual and multi-criteria scaling-up in terms of operating conditions, geometry, and both together, the usefulness of the approach being demonstrated. A few experiments are also performed in order to validate the concept. DOI : 10.3139/217.2200 En ligne : https://drive.google.com/file/d/1bL7jMcelXrDDZBRCwGbqXzDzV2sAcZsK/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=4209
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Code-barres Cote Support Localisation Section Disponibilité 011139 - Périodique Bibliothèque principale Documentaires Disponible Film blowing of PHB-based systems for home compostable food packaging / P. F. Teixeira in INTERNATIONAL POLYMER PROCESSING, Vol. XXXV, N° 5 (11/2020)
PermalinkImproving the thickness distribution of parts with hybrid thermoforming / Fernando M. Duarte in INTERNATIONAL POLYMER PROCESSING, Vol. 37, N° 4 (2022)
PermalinkModeling of agglomerate dispersion in single screw extruders / N. Domingues in INTERNATIONAL POLYMER PROCESSING, Vol. XXV, N° 3 (07/2010)
PermalinkMonitoring reactive processes along the extruder / Jose A. Covas in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 2 (06/2005)
PermalinkMonitoring the production of polymer nanocomposites by melt compounding with on-line rheometry / S. T. Mould in INTERNATIONAL POLYMER PROCESSING, Vol. XXVII, N° 5 (11/2012)
PermalinkOn the use of the heating stage to control the thickness distribution in thermoformed parts / Fernando M. Duarte in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 2 (06/2004)
PermalinkOptimization of processing conditions for polymer twin-screw extrusion / A. Gaspar-Cunha in INTERNATIONAL POLYMER PROCESSING, Vol. XVII, N° 3 (09/2002)
PermalinkPreparation of polymer-clay nanocomposites by melt mixing in a twin screw extruder : using on-line SAOS rheometry to assess the level of dispersion / S. Mould in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)
PermalinkThe design of extrusion screws : an optimization approach / A. Gaspar-Cunha in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)
PermalinkVisualisation 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)
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