Analysis of a single screw extruder with a grooved plasticating barrel - Part I : the melting model / José Antonio Avila Alfaro in INTERNATIONAL POLYMER PROCESSING, Vol. XXX, N° 2 (05/2015)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXX, N° 2 (05/2015) Titre : Analysis of a single screw extruder with a grooved plasticating barrel - Part I : the melting model Type de document : texte imprimé Auteurs : José Antonio Avila Alfaro, Auteur ; Eberhardt Grünschloß, Auteur ; Stefan Epple, Auteur ; Christian Bonten, Auteur Année de publication : 2015 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Extrudeuse monovis Matières plastiques -- Extrusion -- Appareils et matériels Modèles mathématiques Polymères -- Fusion Prévision, Théorie de la Vis barrière Index. décimale : 668.4 Plastiques, vinyles Résumé : Single screw extruders with barrier screws, grooved feed zones and grooved melting zones were introduced to the European plastics industry in 1999. These extruders have an improved melting and conveying capacity among other advantages, such as a lower melt temperature, less wear, less torque and less energy consumption. The aim of this paper is to present a mathematical model for predicting the melting rate in this type of extrusion system. Based on the classical melting mechanism observed in conventional extruders, it was possible to study the effect of the geometry of the grooved barrel on the melting rate of a polymer. It was shown that the grooves on the barrel notably increase the melting rate, when compared to conventional single screw extruders. A good agreement between theory and experimental data was found. Note de contenu : - THEORETICAL MODEL : Melting rate in the space between two grooves - EXPERIMENTS : Model validation - Parameter study - RESULTS AND DISCUSSION : Solid bed length validation - Melting rate validation - Parameter study - Extruder simulation DOI : 10.3139/217.3021 En ligne : https://drive.google.com/file/d/1ovEnaF589jCnoFhVELhjOll5L4VAA8D8/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=23911 [article]

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Barrier screw compounding and mechanical properties of EAA copolymer and cellulose fiber composite / Ruth Ariño in INTERNATIONAL POLYMER PROCESSING, Vol. XXVIII, N° 4 (08/2013)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVIII, N° 4 (08/2013) . - p. 421-428 Titre : Barrier screw compounding and mechanical properties of EAA copolymer and cellulose fiber composite Type de document : texte imprimé Auteurs : Ruth Ariño, Auteur ; A. Boldizar, Auteur Année de publication : 2013 Article en page(s) : p. 421-428 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres végétales -- Extrusion Composites à fibres végétales -- Moulage par injection Composites à fibres végétales -- Propriétés mécaniques Copolymère éthylène acide acrylique Distribution et orientation des fibres Fibres cellulosiques Vis barrière Index. décimale : 668.4 Plastiques, vinyles Résumé : The difficulty of feeding cellulose fibers and thermoplastics into the extruder or injection molding machine is addressed, this being a serious problem in the production of cellulose fiber composites for industrial applications. Agglomerates consisting in cellulose fibers and ethylene-acrylic acid copolymer (EAA) with different cellulose contents and different fiber lengths were processed with two different screws in order to better understand how the dispersion of the fibers can be improved by melt extrusion. A conventional screw with a compression ratio of 4:1 and a screw with barrier flights were used at different screw rotation speeds. The fiber length and fiber content were measured and microscopic analyses were performed in order to estimate the number and size of the cellulose fiber aggregates in the final composites. It was concluded that the barrier screw was more effective than the conventional screw in breaking up the fiber aggregates and dispersing the fibers. More but smaller cellulose aggregates were observed when the barrier screw was used, and the reduction of length was significantly greater for long than for short fibers. In contrast to that was expected, the samples containing the shorter fibers had better mechanical properties, probably due to a better dispersion of the fibers. Note de contenu : - EXPERIMENTAL : Materials - Melt processing - Measurements - RESULTS AND DISCUSSION : Visual characterization - Microscope image characterization - Fiber dimensions - Fiber content - Tensile properties DOI : 10.3139/217.2772 En ligne : https://drive.google.com/file/d/1pc6ZPOsiGncrnENBDZ83P7k0asTzKHEK/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=19287 [article]

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Melt processing of wood cellulose tissue and ethylene-acrylic copolymer composites / Ruth Ariño in INTERNATIONAL POLYMER PROCESSING, Vol. XXVIII, N° 4 (08/2013)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVIII, N° 4 (08/2013) . - p. 429-436 Titre : Melt processing of wood cellulose tissue and ethylene-acrylic copolymer composites Type de document : texte imprimé Auteurs : Ruth Ariño, Auteur ; A. Boldizar, Auteur Année de publication : 2013 Article en page(s) : p. 429-436 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bois Cellulose La cellulose est un glucide constitué d'une chaîne linéaire de molécules de D-Glucose (entre 200 et 14 000) et principal constituant des végétaux et en particulier de la paroi de leurs cellules. Composites à fibres végétales -- Propriétés mécaniques Copolymère éthylène acide acrylique Extrudeuse bi-vis Extrudeuses Mélange Textiles et tissus Vis barrière Index. décimale : 668.4 Plastiques, vinyles Résumé : The difficulty of feeding cellulose fibers together with the polymer into the melt processing equipment is a serious disadvantage for the production of cellulose-containing composites on a large scale. In the present work, a continuous method of feeding cellulose in the form of a tissue into a twin-screw extruder through an opening downstream of the extruder cylinder was studied. With this method, composites with different fiber contents were obtained. The tissues used were one made mainly of softwood fibers and another mainly of hardwood fibers. In order to better understand how to improve the fiber dispersion by melt mixing, a second extrusion was performed with a single screw extruder with a barrier-flighted screw and also with the twin-screw used to compound the tissue with the polymer. The compounds produced were then injection molded into test bars. The test bars containing the softwood tissue exhibited some fiber aggregates also after a second extrusion, whereas no fiber aggregates were observed in samples made with the tissue containing hardwood fibers and two passes through the twin screw. The fiber length was in general reduced by each melt processing stage and the shortest fiber length was observed after two extrusions with the twin-screw and injection molding. The tensile modulus increased with increasing fiber content. A higher stiffness was obtained with more softwood fibers in the tissue whereas more hardwood fibers gave a higher tensile strength and greater elongation at break. Note de contenu : - EXPERIMENTAL : Materials - Melt processing - Measurements - RESULTS AND DISCUSSION : Fiber content - Visual characterization - Microscope analysis - Fiber length - Tensile properties DOI : 10.3139/217.2773 En ligne : https://drive.google.com/file/d/1aA9xrzdk3bKtvqEBDoxAnBQfQR8_xdi7/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=19288 [article]

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Screws for large shot weights / Thomas Hungerkamp in KUNSTSTOFFE INTERNATIONAL, Vol. 107, N° 4 (04/2017)  

[article]  inKUNSTSTOFFE INTERNATIONAL > Vol. 107, N° 4 (04/2017) . - p. 30-32 Titre : Screws for large shot weights : Barrier screw from KraussMaffei shortens the cycle time and improves the melt homogeneity Type de document : texte imprimé Auteurs : Thomas Hungerkamp, Auteur ; Klaus Zeiler, Auteur Année de publication : 2017 Article en page(s) : p. 30-32 Langues : Anglais (eng) Catégories : Matières plastiques -- Moulage par injection Temps de cycle (production) -- Réduction Vis barrière Index. décimale : 668.4 Plastiques, vinyles Résumé : When it comes to injection molding applications with large-volume moldings such as bottle crates, pallet boxes or containers, the plasticizing system has a crucial influence on the productivity. Only when plasticizing is performed quickly and effectively can short cycle times and high product quality be combined. Applications with large shot weights, in particular, allow barrier screws to demonstrate their advantages compared with conventional screws. Note de contenu : - Measures to increase output - Barrier screws on the advance - Identification of the optimum screw geometry - Benefits for the processor - FIGURES : 1. During the production of large-volume injection moldings such as pallets and pallet boxes, the shot weight is often in excess of 10 kg - 2. Principle design of the barrier - 3. Calculated melting profile with an unfavorable screw design : the conveying capacity of the screw is higher than is melting capacity - 4. Calculated melting profild with a favorable screw design : The proportion of molten material reaches 100% even before the end of the barrier zone En ligne : https://drive.google.com/file/d/1tsTJZVjfcJzWhmnBwoGcfMJ5fQFASzds/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28478 [article]

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The effect of vehicle on skin absorption of Mg2+ and Ca2+ from thermal spring water / M. Tarnowska in INTERNATIONAL JOURNAL OF COSMETIC SCIENCE, Vol. 42, N° 3 (06/2020)  

[article]  inINTERNATIONAL JOURNAL OF COSMETIC SCIENCE > Vol. 42, N° 3 (06/2020) . - p. 248-258 Titre : The effect of vehicle on skin absorption of Mg2+ and Ca2+ from thermal spring water Type de document : document électronique Auteurs : M. Tarnowska, Auteur ; Stéphanie Briançon, Auteur ; J. Resende de Azevedo, Auteur ; Yves Chevalier, Auteur ; D. Arquier, Auteur ; C. Barratier, Auteur ; Marie-Alexandrine Bolzinger, Auteur Année de publication : 2020 Article en page(s) : p. 248-258 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Absorption cutanée Barrière cutanée Calcium Emulsions -- Emploi en cosmétologie Franz, Cellules de Ions métalliques Liposomes Magnésium Le magnésium est l'élément chimique de numéro atomique 12, de symbole Mg. Le magnésium est un métal alcalino-terreux. Il s’agit du neuvième élément le plus abondant de l'univers . Il est le produit, dans de grandes étoiles vieillissantes, de l'addition séquentielle de trois noyaux d'hélium à un noyau carbo. Lorsque de telles étoiles explosent en tant que supernovas, une grande partie du magnésium est expulsé dans le milieu interstellaire où il peut se recycler dans de nouveaux systèmes stellaires. Le magnésium est le huitième élément le plus abondant de la croûte terrestreet le quatrième élément le plus commun de la Terre (après le fer, l'oxygène et le silicium), constituant 13 % de la masse de la planète et une grande partie du manteau de la planète. C'est le troisième élément le plus abondant dissous dans l'eau de mer, après le sodium et le chlore. Les atomes de magnésium existent dans la nature uniquement sous forme de combinaisons avec d'autres éléments, où il présente invariablement l'état d'oxydation +2. L'élément pur est produit artificiellement par réduction ou électrolyse. Il est hautement réactif en poudre et en copeaux mais, laissé à l'air libre, il se revêt rapidement d'une mince couche d'oxyde étanche réduisant sa réactivité (passivation par oxydation). Le métal pur brûle aisément sous certaines conditions (en produisant une lumière brillante, blanche, éblouissante caractéristique). En mécanique il est utilisé principalement comme composant dans les alliages d'aluminium-magnésium (parfois appelés magnalium). Le magnésium est moins dense que l'aluminium et l'alliage est apprécié pour sa légèreté et sa résistance plus grande (mécanique et chimique). (Wikipedia) Peau -- Soins et hygiène Pénétration (physique) Sources thermales Vectorisation Vis barrière Index. décimale : 668.5 Parfums et cosmétiques Résumé : - Objective : Thermal spring waters (TSW) are commonly used as active ingredients in cosmetics. Their biological activities directly depend on the ionic composition of the spring. However, in order to exhibit beneficial properties, the minerals need to reach viable skin layers. The present study addresses the incorporation of marketed TSW in model cosmetic formulations and the impact of the formulation on skin absorption of magnesium and calcium ions that are known to improve skin barrier function. - Methods : Marketed TSW was introduced into five formulations. Liposomes were prepared using saturated or unsaturated phospholipids mixed with cholesterol by the thin layer evaporation technique. Emulsions water-in-oil (W/O), oil-in-water (O/W) or double: water-in-oil-in-water (W/O/W) were prepared by high-shear mixing. Skin absorption of Mg2+ and Ca2+ from those formulations was studied in vitro using static Franz diffusion cells under infinite dose condition and under occlusion of the apparatus. - Results : Mg2+ and Ca2+ penetrate skin samples from TSW. Encapsulating TSW into double emulsion (TSW/O/W) increased skin absorption of both cations of interest and kept the Ca2+/Mg2+ ratio equal to that of TSW in each skin layer. The dermal absorption of Mg2+ from the double emulsion departs from both single emulsions. Application of liposome suspension improved the skin absorption of Ca2+ while keeping constant that of Mg2+, leading to unbalanced Ca2+/Mg2+ ratio inside skin. - Conclusion : The beneficial effects of TSW are not only due to their action on the skin surface. Their active components, especially Ca2+ and Mg2+ cations, reach viable skin layers in a formulation-dependent manner. The distribution of ions inside skin depends on the type of formulation. Note de contenu : - Materials - TSW physicochemical characterization - Formulation manufacture - pH measurements - Skin permeation studies - Table 1 : Characterization of TSW. Values in standard font are given accord¬ing to the supplier, and values in italics are the measurements made by our own - Table 2 : Composition of the formulations. Values are given as % m/m of the final preparation - Table 3 : Physicochemical characterization of liposomes made of saturated and unsaturated phospholipids (LPM-90H and LPM-90G, respectively) and three emulsion types : O/TSW, TSW/O/W and TSW/O. Mean size of emulsion droplets was estimated from optical microscopy observations ; those for liposomes were measured by dynamic light scattering (mean size and PDI) - Table 4 : Results of dermal absorption of Ca2+ and Mg2+ from the emulsions and liposomes in nmol cm-2. The values represent the mean values of 8 experiments and are expressed as mean ± SEM. Ca2+ : Mg2+ ratios (R) were calculated based on the mean values obtained for each skin layer DOI : https://doi.org/10.1111/ics.12607 En ligne : https://drive.google.com/file/d/1Nu-TuWxdaruwasj0oAlbcHdPj6jMeKaF/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=35272 [article]

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Virtual melting and feed section design / Christian Hopmann in KUNSTSTOFFE INTERNATIONAL, Vol. 103, N° 10 (10/2013)

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