On-line visualization of PS/PP melting mechanisms in a co-rotating twin screw extruder / H. Chen in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 4 (12/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 4 (12/2004) . - p. 342-349 Titre : On-line visualization of PS/PP melting mechanisms in a co-rotating twin screw extruder Type de document : texte imprimé Auteurs : H. Chen, Auteur ; Uttandaraman Sundararaj, Auteur ; K. Nandakumar, Auteur ; Marc D. Wetzel, Auteur Année de publication : 2004 Article en page(s) : p. 342-349 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The melting and deformation mechanisms of polystyrene (PS) and polypropylene (PP) blends were investigated through online visualization of the co-rotating twin-screw extrusion process. Two compositions, PP/PS (80 : 20) and PS/PP (80: 20) were chosen as the model systems for this study. A sliding barrel technique was used to realize the on-line visualization using a glass window in the barrel. The axial temperature and pressure profiles along the screw channel were measured using the same sliding technique. It was found that in the PP/PS (80 : 20) blend, in which PP was the major phase, there was a combined melting of PS and PP, whereas in the PS/PP (80 : 20) blend, in which PS was the major phase, there was initial melting of PS alone and then combined melting of PS and PP. In the partially filled region, heat conduction from the hot barrel was the major source for heating polymer pellets under the conditions studied here; while in the fully filled region, viscous energy dissipation (VED) generated most of the heat for melting of polymer pellets. The pressure profiles along the extrusion channel gave us insight into the melting process for the two blends. It was found that if there was some molten polymer in the fully filled region, the overall melting process was accelerated due to heating from viscous dissipation. DOI : 10.3139/217.1839 En ligne : https://drive.google.com/file/d/10PY5_vzTyQSVXV4mDMnjen2b4gCW2d3l/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3266 [article]

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A study of concentrated suspensions in polyethylene melts and the impact on viscosity and polymer processing operations / Marc D. Wetzel in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIII, N° 4 (08/2018)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIII, N° 4 (08/2018) . - p. 574-587 Titre : A study of concentrated suspensions in polyethylene melts and the impact on viscosity and polymer processing operations Type de document : texte imprimé Auteurs : Marc D. Wetzel, Auteur ; G. A. Campbell, Auteur Année de publication : 2018 Article en page(s) : p. 574-587 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Carbonate de calcium Le carbonate de calcium (CaCO3) est composé d'un ion carbonate (CO32-) et d'un ion calcium (Ca2+), sa masse molaire est de 100,1 g/mole. C'est le composant principal du calcaire et de la craie, mais également du marbre. C'est aussi le principal constituant des coquilles d'animaux marins, du corail et des escargots. Charges (matériaux) Dioxyde de titane Etat fondu (matériaux) Malaxeurs et mélangeurs Mélanges-maîtres (chimie) Percolation Polyéthylène basse densité linéaire Rhéologie Viscosité Index. décimale : 668.4 Plastiques, vinyles Résumé : Filled polymer compounds can present processing challenges, including poor dispersive mixing, high screw shaft torque and energy consumption, flow instabilities, and significant increases in melt pressures and temperatures. Previous theoretical development and experimental evaluations of polymer melts filled with particulate solids showed that the viscosity can be described with a model based on percolation theory concepts. This paper describes a batch mixer characterization method developed to measure the effects of filler concentration and operating conditions on the melt viscosity and process response. Experimental results are compared with capillary rheometer measurements using several low-density polyethylene resins, calcium carbonate and titanium dioxide. The theoretical treatment of the viscosity as a particulate percolating system with power-law behavior was used to analyze and compare rheometer and batch mixer data. The effects of resin molecular weight, filler type and size on viscosity and melt processing were examined and there was good agreement between rheometer and mixer viscosity trends, and percolation model predictions. The laboratory experiments and model estimates provide quantitative information that can be used to develop and troubleshoot extrusion compounding, single screw extrusion and low-shear forming processes. Note de contenu : - MATERIAL SYSTEMS AND MASTERBATCHES - RHEOLOGY MEASUREMENTS AND MODELS : Modified percolation-based filler concentration viscosity model - LDPE/TiO2 system - LLDPE/CaCO3 system - BATCH MIXER EXPERIMENTS : LLDPE/CaCO3 system - EFFECTS OF POLYMER TYPE, FILLER TYPE AND SIZE : LDPE/TiO2 system - DISCUSSION AND IMPACTS ON POLYMER PROCESSING DOI : 10.3139/217.3577 En ligne : https://drive.google.com/file/d/13HWzo5EDjdthp4Dlsr4ZA3LacgS15Ksj/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=30897 [article]

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