Determining the coefficients of friction for bulk plastics / Gernot Zitzenbacher in KUNSTSTOFFE PLAST EUROPE, Vol. 95, N° 4/2005 (04/2005)

[article]  inKUNSTSTOFFE PLAST EUROPE > Vol. 95, N° 4/2005 (04/2005) . - p. 43-47 Titre : Determining the coefficients of friction for bulk plastics Type de document : texte imprimé Auteurs : Gernot Zitzenbacher, Auteur ; Günter R. Langecker, Auteur ; Rudolf Schatzer, Auteur Année de publication : 2005 Article en page(s) : p. 43-47 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.4 Plastiques, vinyles Résumé : Measurement technology - Both the internal and external coefficients of friction are decisive for solids conveying in single-screw extruders. A new friction measuring instrument based on the principle of a vertically oriented solids-conveying extruder permits measurement of the coefficients of friction as a function of pressure, temperature and velocity under nearly real-world processing conditions. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=7493 [article]

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Modeling and estimation of the pressure and temperature dependent bulk density of polymers / Christian Kneidinger in INTERNATIONAL POLYMER PROCESSING, Vol. XXXV, N° 1 (03/2020)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXV, N° 1 (03/2020) . - p. 70-82 Titre : Modeling and estimation of the pressure and temperature dependent bulk density of polymers Type de document : texte imprimé Auteurs : Christian Kneidinger, Auteur ; M. Längauer, Auteur ; Gernot Zitzenbacher, Auteur ; S. Schuschnigg, Auteur ; Jürgen Miethlinger, Auteur Année de publication : 2020 Article en page(s) : p. 70-82 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Extrudeuse monovis Masse volumique Mesure Modèles mathématiques Polymères Pression Index. décimale : 668.4 Plastiques, vinyles Résumé : The bulk density of polymers is a crucial factor for the throughput and the pressure build-up of single screw plasticating units. It depends not only on the density of the polymeric material itself, but also on the geometry of the single pellets, on the dimensions of the screw channel and, furthermore, on the temperature and the pressure. A review of the existing models shows that there is potential for improvement, as their applicability is restricted. It is difficult to obtain model parameters, as they can only be determined by experiment, but there are only a few devices which enable temperature- and pressure-dependent bulk density to be measured. Furthermore, these devices are not standardized. This work presents a new model which can be used to calculate the bulk density as a function of pressure and temperature and an adapted approach that considers the dimensions of the single pellets and the screw channel. The model is verified by both, new data derived from experiments and data from the literature. Compared to existing models, this new model fits the experimental data better, requires fewer parameters and shows much better extrapolation behavior as well as a continuous changeover behavior at the melting temperature. Another big advantage of the new model compared to the existing ones is that the model parameters of this new model can be estimated from the stress at yield and from the melting temperature. This enables a rough estimation of the pressure and temperature dependent bulk density without having to measure it. Note de contenu : - INTRODUCTION : Measurement of the bulk density - Existing models - Evaluation of the existing models - PROPOSED MODEL : Material density - Adjustable approach - Simplified approach - Combined approach - Modification by implementation of the volumetric transition temperature - Modifications considering the temperature dependence of the bulk density at zero pressure - Consideration of the screw channel geometry - Benefits of the new model compared to the existing models - Parameter fitting - MATERIALS USED - RESULTS AND DISCUSSION - ESTIMATING MODEL PARAMETERS FROM MATERIAL PROPERTIES DOI : https://doi.org/10.3139/217.3876 En ligne : https://drive.google.com/file/d/1jH3kB_e72-_OymLxouI82g5CYVTN2VzK/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33780 [article]

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Modeling temperature and time dependence of the wetting of tool steel surfaces by polymer melts / Gernot Zitzenbacher in INTERNATIONAL POLYMER PROCESSING, Vol. XXXII, N° 2 (05/2017)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXII, N° 2 (05/2017) . - p. 245-252 Titre : Modeling temperature and time dependence of the wetting of tool steel surfaces by polymer melts Type de document : texte imprimé Auteurs : Gernot Zitzenbacher, Auteur ; M. Längauer, Auteur ; C. Holzer, Auteur Année de publication : 2017 Article en page(s) : p. 245-252 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Acier L'acier est un alliage métallique utilisé dans les domaines de la construction métallique et de la construction mécanique. L'acier est constitué d'au moins deux éléments, le fer, très majoritaire, et le carbone, dans des proportions comprises entre 0,02 % et 2 % en masse1. C'est essentiellement la teneur en carbone qui confère à l'alliage les propriétés du métal qu'on appelle "acier". Il existe d’autres métaux à base de fer qui ne sont pas des aciers comme les fontes et les ferronickels par exemple. Angle de contact Etat fondu (matériaux) Métaux -- Surfaces Modèles mathématiques Mouillage (chimie des surfaces) Polyméthacrylate de méthyle Le poly(méthacrylate de méthyle) (souvent abrégé en PMMA, de l'anglais Poly(methyl methacrylate)) est un polymère thermoplastique transparent obtenu par polyaddition dont le monomère est le méthacrylate de méthyle (MMA). Ce polymère est plus connu sous son premier nom commercial de Plexiglas (nom déposé), même si le leader global du PMMA est Altuglas International9 du groupe Arkema, sous le nom commercial Altuglas. Il est également vendu sous les noms commerciaux Lucite, Crystalite, Perspex ou Nudec. Polypropylène Index. décimale : 668.4 Plastiques, vinyles Résumé : Beside the surface properties of the tool material, its temperature is an important parameter influencing the wettability of the tool surface by polymer melts in extrusion technology and injection molding. The temperature and time dependence of the contact angle of a polypropylene and a polymethylmethacrylate melt on polished tool steel was studied in this work at close to process conditions. The experiments were conducted by placing the polymeric sample on the hot tool material substrate in a high temperature chamber and recording the drop shape dependence on time. Based on the experimental results, a novel model was developed which allows a description of the contact angle dependent on temperature and time. The contact angle of the investigated polymer melts exhibits a linear decrease with rising temperature, which means that the wettability of the tool material by the polymer melt is improved with increasing temperature. Furthermore, the model proposed herein enables a complete mathematical description of the contact angle of polymer melts on the tool material dependent on temperature and time. The parameters of this function are the initial contact angle ?0, the contact angle when time approaches infinity ?? and a characteristic material time B. The time dependency is incorporated by an exponential function. The characterizing contact angle parameters (?0, ??) follow a linear decrease with rising temperature. The characteristic material time B obeys an exponential law dependent on the reciprocal value of temperature similar to Arrhenius' law. Note de contenu : - EXPERIMENTAL : Materials - Determination of surface roughness - Determination of the contact angle of the polymer melts - RESULTS AND DISCUSSION : Temperature dependence of the contact angle - Modeling time and temperature dependence of the contact angle DOI : 10.3139/217.3340 En ligne : https://drive.google.com/file/d/12TWebHMjzkjDu-LsGFJvTFTUHe729_qV/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28522 [article]

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A new calculation model and optimization method for maddock mixers in single screw plasticising technology / Gernot Zitzenbacher in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 1 (03/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 1 (03/2007) . - p. 73-81 Titre : A new calculation model and optimization method for maddock mixers in single screw plasticising technology Type de document : texte imprimé Auteurs : Gernot Zitzenbacher, Auteur ; R. Karlbauer, Auteur ; H. Thiel, Auteur Année de publication : 2007 Article en page(s) : p. 73-81 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A homogenous melt is the prerequisite to achieve the demanded product quality in single screw plasticising technology. At higher screw speeds and mass flow rates solid particles can occur in the melt. Dispersive mixing elements are often used to improve the melt quality. Calculation models are necessary for designing mixing elements in the right way. A new model for the often used fluted mixing sections like axial and spiral Maddock-elements and Z-elements is presented in this paper. The calculation model is reduced to a single pair of inlet and outlet flute, connected by the shearing gap. Especially in spiral Maddock mixers the longitudinal flow in the flutes is a combined pressure and drag flow but in axial Maddock mixers pure pressure flow occurs. In the shearing gap a combined pressure and drag flow can occur. The leakage flow through the flight clearance is also considered. Geometry functions are introduced for considering the rectangular or circular segment shaped cross section of the flutes. The viscosity is shear rate and temperature dependent, the channel height as well as the channel width can vary along the mixing element. The model allows the calculation of the longitudinal pressure profile in the inlet and outlet flutes, the total pressure drop and the shear stress distribution in the shearing gap. Mixing sections sometimes show a too high pressure consumption and insufficient shearing efficiency. Therefore a geometry optimization method for axial Maddock mixing heads is presented in this paper. DOI : 10.3139/217.0109 En ligne : https://drive.google.com/file/d/1Kw-wAE8zHMoWiyi2bEZPFamzTdKlGcy7/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2771 [article]

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A new plasticating model for amorphous and semi-crystalline polymers in single screw extruders / Gernot Zitzenbacher in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 4 (12/2005)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XX, N° 4 (12/2005) . - p. 360-368 Titre : A new plasticating model for amorphous and semi-crystalline polymers in single screw extruders Type de document : texte imprimé Auteurs : Gernot Zitzenbacher, Auteur ; Günter R. Langecker, Auteur Année de publication : 2005 Article en page(s) : p. 360-368 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Appareils et matériel Matières plastiques -- Extrusion:Polymères -- Extrusion Polymères amorphes Polymères semi-cristallins Index. décimale : 668.9 Polymères Résumé : Polymeric thermoplastic materials can be subdivided in amorphous and semi-crystalline ones. In contrast to semi-crystalline polymers amorphous thermoplastic materials have no defined phase transition and hence no melt enthalpy. The glass transition region describes the change of the material behaviour from the state of a rubber like to an under-cooled fluid (glassy state). Setting the melt enthalpy in the Stefan-Neumann problem zero gives no valid results for the solid bed profile. Thus this condition is unsuitable for describing the plasticating process of amorphous polymers. In this paper a new model for the plastication of amorphous and semi-crystalline polymers in single screw extruders is presented. Therefore a new calculation method for the determination of the moving velocity between the glassy solid bed and the softened film region on the barrel surface is developed. The whole enthalpy to heat up the polymer on a critical flow temperature in the screw channel is considered. En ligne : https://drive.google.com/file/d/1E-cLwCkUp-xA1Oi0HPNJO9e2ylxkEga6/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2961 [article]

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Study of heat absorption in thermoforming for transparent and filled polystyrene / Josef Friedrich Puehringer in INTERNATIONAL POLYMER PROCESSING, Vol. XXVIII, N° 1 (03/2013)  

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