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Effect of the chemical and morphological conditions of the die wall on the extrusion of linear polyolefins / H. J. Larrazabal in INTERNATIONAL POLYMER PROCESSING, Vol. XXI, N° 2 (05/2006)
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Titre : Effect of the chemical and morphological conditions of the die wall on the extrusion of linear polyolefins Type de document : texte imprimé Auteurs : H. J. Larrazabal, Auteur ; John Vlachopoulos, Auteur ; Andrew N. Hrymak, Auteur Année de publication : 2006 Article en page(s) : p. 132-140 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : This study examines the effects of average surface roughness and composition of the die wall surface on the critical shear stress for the onset of instabilities in die extrusion. Increasing the average surface roughness of the die wall from 0.1 to 15 lm produced an increase of the critical shear stress for the onset of flow instabilities by as much as 20% during the extrusion of HDPE. The surface of the extrudates obtained with dies having an average surface roughness greater than 5 lm showed lines and grooves along the direction of extrusion. Chrome-plated and nickel-plated dies showed an average 28% increase in the critical shear stress as compared to conventional steel dies. The chemical composition of uncoated steel dies wall surfaces, including the presence of iron oxide, did not affect the critical shear stress for the onset of sharkskin significantly regardless of the type of resin used. DOI : 10.3139/217.0067 En ligne : https://drive.google.com/file/d/1Yxiub4WHfm2v8T1JdUQyyg_03cF_TsAl/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2906
in INTERNATIONAL POLYMER PROCESSING > Vol. XXI, N° 2 (05/2006) . - p. 132-140[article]Réservation
Réserver ce documentNegative pressures in modelling rotating polymer processing machinery are meaningless, but they are telling something / A. Goger in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 2 (05/2014)
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Titre : Negative pressures in modelling rotating polymer processing machinery are meaningless, but they are telling something Type de document : texte imprimé Auteurs : A. Goger, Auteur ; John Vlachopoulos, Auteur ; M. R. Thompson, Auteur Année de publication : 2014 Article en page(s) : p. 295-297 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Machines tournantes
Matières plastiques -- Extrusion
Pression -- Mesure
Simulation par ordinateurIndex. décimale : 668.9 Polymères Résumé : In the technical literature, some authors have reported calculation of negative pressures in simulations of twin screw extrusion and other types of processing, without giving any explanations. In the majority publications there is no mention of such meaningless results, even though theoretical considerations indicate that negative pressures could be obtained in the expansion region of drag flows through narrow non-parallel surfaces. The meaningless negative pressures are due to the application of single fluid theory to flow regions where bubbles would form, when the pressure drops below the vapor pressure of the liquid. This has been known for a long time from the study of lubrication bearings and related cavitation phenomena. It is argued that the boundary conditions should be carefully chosen for avoiding results in numerical simulations, which can never be reconciled with experimental pressure data. DOI : 10.3139/217.2706 En ligne : https://drive.google.com/file/d/16cYBjKfVI60cikbcNOeU95qTqmtH6uo5/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21325
in INTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 2 (05/2014) . - p. 295-297[article]Réservation
Réserver ce documentNumerical study of internal bubble cooling (IBC) in film blowing / V. Sidiropoulos in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 1 (03/2001)
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Titre : Numerical study of internal bubble cooling (IBC) in film blowing Type de document : texte imprimé Auteurs : V. Sidiropoulos, Auteur ; John Vlachopoulos, Auteur Année de publication : 2001 Article en page(s) : p. 48-53 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Numerical simulation of turbulent airflow emerging from an Internal Bubble Cooling (IBC) stack and directly impinging on the internal surface of a blown film bubble has been carried out. The streamline pattern and heat flux are determined through a finite volume numerical technique using a version of k-M turbulence modeling. It is shown that balancing the airflow between the multiple slits of the stack is useful to increase the internal cooling rates, but may require more elaborate designs of the inlet pipe. As the air flows towards the internal bubble surface there is significant deceleration which diminishes the effectiveness of the heat removal mechanisms. Depending on the flow rates and geometrical configurations the airflow may induce compressibility effects at the exhaust pipe. The numerical results suggest that Internal bubble Cooling (IBC) equipment introduces distinctive design and operation challenges. Note de contenu : - Literature review
- Theory and simulation methodology
- IBC design sensitivityDOI : 10.3139/217.1625 En ligne : https://drive.google.com/file/d/1-aUdxJpSQBlEb412O2XEEAWvy1bhxvlQ/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15884
in INTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 1 (03/2001) . - p. 48-53[article]Réservation
Réserver ce documentRheological evaluation and observations of extrusion instabilities of biodegradable polyesters / D. Kanev in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 5 (11/2007)
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Titre : Rheological evaluation and observations of extrusion instabilities of biodegradable polyesters Type de document : texte imprimé Auteurs : D. Kanev, Auteur ; E. Takacs, Auteur ; John Vlachopoulos, Auteur Année de publication : 2007 Article en page(s) : p. 395-401 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The rheological properties of two commercially available biodegradable polyesters - poly(lactic acid) (PLA) and aliphatic-aromatic co-polyester EcoflexTM - have been investigated. The rheological study was focused on measuring the viscosity and examining sharkskin, melt fracture, and extrudate swell phenomena, which are crucial in industrial applications. The experiments show that the two biodegradable polyesters exhibit shear-thinning behavior similar to other polymers and the Cox-Merz rule is obeyed. It was observed that with increasing shear rate PLA exhibits sharkskin and gross melt fracture while EcoflexTM exhibits only gross melt fracture. Experimental results indicate that both biodegradable polyesters exhibit small extrudate swell, up to 28% for PLA and up to 34% for EcoflexTM. DOI : 10.3139/217.2053 En ligne : https://drive.google.com/file/d/1m-jb34vPC9-m2PWWJETor-8mjT7HqNrO/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2680
in INTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 5 (11/2007) . - p. 395-401[article]Réservation
Réserver ce documentRheology and processing of HDPE/wood flour composites / Cristiano R. Santi in INTERNATIONAL POLYMER PROCESSING, Vol. XXIV, N° 4 (09/2009)
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Titre : Rheology and processing of HDPE/wood flour composites Type de document : texte imprimé Auteurs : Cristiano R. Santi, Auteur ; E. Haje, Auteur ; John Vlachopoulos, Auteur ; Carlos A. Correa, Auteur Année de publication : 2009 Article en page(s) : p. 346-353 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bois
Composites à fibres végétales
Farines végétales
Polyéthylène haute densité
RhéologieIndex. décimale : 668.4 Plastiques, vinyles Résumé : Rheological and mechanical properties of extruded wood plastic composites have been investigated for the purpose of providing a better understanding of processing conditions in profile extrusion for this novel class of thermoplastics composites. The basic formulations prepared for the study were comprised of 60 wt.% HDPE, with or without LLDPE-MAH as coupling agent, compounded with up to 40 wt.% of wood flour and lubricant. Capillary and rotational rheometers were employed to measure the rheological properties of the melt composite. A cooled die at the end of a single screw extruder was used for the extrusion of rectangular profiles having smooth surfaces and edges. Finite element flow simulation was used for the interpretation of the experimental data. Once extrusion steady conditions were achieved in the die, linear output was monitored and profile samples were cut for determination of flexural modulus and strength. The results showed that flexural properties can be influenced by many factors such as, coupling agents, lubricants, processing conditions, die pressure drop and cooling at the die. Linear speed of HDPE wood-plastic profile extrusion and end-use properties are strongly influenced by combination of these factors. DOI : 10.3139/217.2238 En ligne : https://drive.google.com/file/d/1srkpykc8qQpqwXd2-E-b_0iY-olmphp6/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=6079
in INTERNATIONAL POLYMER PROCESSING > Vol. XXIV, N° 4 (09/2009) . - p. 346-353[article]Réservation
Réserver ce documentTorque viscometry of molten polymers and composites / Cristiano R. Santi in APPLIED RHEOLOGY, Vol. 19, N° 1 (2009)
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