Biaxially oriented PP films using the double bubble process / H. Benkreira in INTERNATIONAL POLYMER PROCESSING, Vol. XVII, N° 3 (09/2002)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVII, N° 3 (09/2002) . - p. 228-232 Titre : Biaxially oriented PP films using the double bubble process Type de document : texte imprimé Auteurs : H. Benkreira, Auteur ; M. C. Talford, Auteur Année de publication : 2002 Article en page(s) : p. 228-232 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Biaxially Oriented Polypropylene (BOPP) film has become an increasingly important commodity over the last 30 or so years, offering an alternative to more traditional cellulose films with much improved mechanical and optical properties. The process is similar to the traditional bubble process for manufacturing films from a polymer melt, and the main difference in modelling the two processes lies in the constitutive equation employed. As the manufacturing process involves large strain deformations, a convected Standard Linear Solid constitutive equation was used in conjunction with the Pearson and Petrie force balance equations and a suitable energy balance to arrive at a mathematical model of the double bubble process. The non-linear ordinary differential equations forming the model require simultaneous solution, carried out using numerical techniques. An experimental program was conducted to obtain large-scale biaxial tensile test data. This data was used to determine the necessary material properties required to allow the model to be applied to a particular commercial process. Material data not obtained thus far has been estimated using previously published data for similar materials. Operating data was obtained from a fully instrumented full-scale industrial bubble process to enable the model to be validated. Initial comparisons between the model results and process data suggest that the model developed is a good starting point for a process simulation but that more accurate material data is required. Note de contenu : - The convected SLS constitutive equation - Dimensionless groups DOI : 10.3139/217.1697 En ligne : https://drive.google.com/file/d/16Plic9MkJS6b08NHO8MjDfiVp34VUMU3/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15998 [article]

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Coating and polymer processing / H. Benkreira in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 1 (03/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 1 (03/2007) . - p. 3-8 Titre : Coating and polymer processing Type de document : texte imprimé Auteurs : H. Benkreira, Auteur Année de publication : 2007 Article en page(s) : p. 3-8 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Coating like polymer processing contributes greatly to the production of thin films using polymers in solutions or in a melt form. From a fluid mechanics perspective, coating operations share common features with polymer processing film operations and it is the purpose of this review to highlight the similarities and help foster a common approach for analysis, design and operation of these processes. DOI : 10.3139/217.2002 En ligne : https://drive.google.com/file/d/12OsvDsv1mbJfFPmVLiVBdQWCR6MGWTMY/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2762 [article]

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Novel extrusion dies with rotating rollers for CO2-plastic foam production / H. Benkreira in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 2 (06/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 2 (06/2004) . - p. 111-117 Titre : Novel extrusion dies with rotating rollers for CO2-plastic foam production Type de document : texte imprimé Auteurs : H. Benkreira, Auteur ; J. Paragreen, Auteur ; M. Cox, Auteur ; R. Patel, Auteur ; M. Gale, Auteur Année de publication : 2004 Article en page(s) : p. 111-117 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : This paper describes a new roller die design capable of generating high pressures to allow the direct injection of liquid carbon dioxide into polymer melts and produce low density foams. The novelty of the design lies in the counter-flow action of a pair of rotating rollers separated by a gap to build up pressure. A mathematical model of the flow in the extrusion-roller die system is described and tested against experimental data with PS, LDPE and PP under a wide range of roller speeds and gaps. The study shows that this new design is feasible but more comprehensive CFD simulations and experiments are required to optimise design and operation to obtain the low-density polymer foams sought. DOI : 10.3139/217.1818 En ligne : https://drive.google.com/file/d/14WeeSJ00ptUXKGzB8Ndrd_MsD1jZ9A6q/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3278 [article]

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Radiant heating of plastics : application to film blowing processes / H. Benkreira in INTERNATIONAL POLYMER PROCESSING, Vol. XVIII, N° 2 (06/2003)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVIII, N° 2 (06/2003) . - p. 179-184 Titre : Radiant heating of plastics : application to film blowing processes Type de document : texte imprimé Auteurs : H. Benkreira, Auteur ; M. C. Talford, Auteur Année de publication : 2003 Article en page(s) : p. 179-184 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : This paper presents experimental data and a mathematical model for the radiant heat transfer operation used in the production of biaxially oriented polypropylene (BOPP) films by the Double Bubble process. The data was obtained from an industrial pilot plant fully instrumented for the purpose of the study. In the mathematical model the effect of the view factor is considered, along with the effects of natural and forced convection on the heat transfer coefficients. Experiments were also conducted in a laboratory radiant heater to determine the range of heat transfer coefficients experienced under different heating conditions, and analytical methods to determine these are discussed. DOI : 10.3139/217.1737 En ligne : https://drive.google.com/file/d/1HIK8zMkfTw4OWbMevQDCupM4jfBctrp6/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3309 [article]

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