A criterion for the formation of fibrillar layers in injection molded parts / R. Pantani in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIII, N° 3 (07/2018)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIII, N° 3 (07/2018) . - p. 355-362 Titre : A criterion for the formation of fibrillar layers in injection molded parts Type de document : texte imprimé Auteurs : R. Pantani, Auteur ; Vito Speranza, Auteur ; G. Titomanlio Année de publication : 2018 Article en page(s) : p. 355-362 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Moulage par injection Polypropylène Simulation par ordinateur Structures fibrillaires Index. décimale : 668.4 Plastiques, vinyles Résumé : It is quite well known that the morphology of an injection molded part made by a semicrystalline polymer presents several layers. In particular spherulitic structures are found in the core region, a layer characterized by highly oriented fibrillar morphology (the shear layer) usually follows and a skin layer is often observed at the sample surface. The thickness of the fibrillar layer deeply influences the mechanical properties of the part. In this work, a criterion to predict the thickness of the fibrillar layer is proposed and verified. The criterion is essentially based on the amount of viscous work done when the molecular stretch is higher than a critical value: the molecular stretch should be above a critical value while a critical amount of viscous work is accumulated. In order to tune the parameters, and to validate the criterion, a well characterized polypropylene was chosen as test material, and four different injection molding conditions were analyzed. The criterion is verified by comparing some experimental results with the prediction of the UNISA code (an injection molding software developed at the University of Salerno), good comparison between software predictions and experimental data confirms the suitability of the criterion. Note de contenu : - INJECTION MOLDING DATA AND PROCESS SIMULATION - INJECTION MOLDING SIMULATIONS : Definition of the molecular stretch parameter - Final distributions of stretch and work and their evolutions - APPLICATION OF THE SIMULTANEITY CRITERION DOI : 10.3139/217.3543 En ligne : https://www.degruyter.com/document/doi/10.3139/217.3543/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=30804 [article]

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Relevance of crystallisation kinetics in the simulation of the injection molding process / R. Pantani in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 1 (03/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 1 (03/2001) . - p. 61-71 Titre : Relevance of crystallisation kinetics in the simulation of the injection molding process Type de document : texte imprimé Auteurs : R. Pantani, Auteur ; Vito Speranza, Auteur ; G. Titomanlio, Auteur Année de publication : 2001 Article en page(s) : p. 61-71 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Modelling of the injection moulding process is carried out in this work on the basis of Williams and Lord model and its recent extensions to post filling stages. the emphasis is devoted to identifying the role of crystallization kinetics in the process simulation. Data of pressure histories during injection moulding of an iPP are taken as a reference to the analysis. Crystallisation kinetics of the material was described by means of a non-isothermal formulation of Avrami model whose parameters where determined either by accounting for only of calorimetric results or by describing also final density data of thin samples subjected to characterised quenching histories. Predictions of pressure histories are analysed in relation to the crystallisation kinetics adopted. the effect of pressure on crystallisation is also discussed. DOI : 10.3139/217.1620 En ligne : https://drive.google.com/file/d/1RZTt1Iy9fT9pvi5dmKzpb21KjP81-y60/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15886 [article]

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Thirty years of modeling of injection molding. A brief review of the contribution of UNISA code to the field / R. Pantani in INTERNATIONAL POLYMER PROCESSING, Vol. XXXI, N° 5 (11/2016)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXI, N° 5 (11/2016) . - p. 655-663 Titre : Thirty years of modeling of injection molding. A brief review of the contribution of UNISA code to the field Type de document : texte imprimé Auteurs : R. Pantani, Auteur ; Vito Speranza, Auteur ; G. Titomanlio, Auteur Année de publication : 2016 Article en page(s) : p. 655-663 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Logiciels Matières plastiques -- Moulage par injection Simulation par ordinateur Index. décimale : 668.4 Plastiques, vinyles Résumé : UNISA code, a software for the analysis and modeling of injection molding, was born at the University of Palermo in Italy in the 1980s. Afterwards, in the 1990s, it was rewritten and expanded at the University of Salerno (Italy) and continuously improved over the years. It is a study code, aimed at understanding rather than simulating. It has the unique characteristic of describing, since the early versions, the morphology of the molded samples. Furthermore, it always implemented the interrelationships among the different material properties (crystallinity, viscosity, density). In this work, the evolution of the software is reviewed, placed in the background, underlining the contribution given to the understanding of polymer processing and morphology evolution. Eventually, the future challenges of modeling are presented. Note de contenu : - The 1980s : basic phenomena are described - Crystallization kinetics, morphology development and flow-induced crystallization - Orientation distribution - Back to flow induced crystallization - Shrinkage and cooling stresses - Boundary conditions and future developments DOI : 10.3139/217.3249 En ligne : https://drive.google.com/file/d/1BdSWqGwvOoI8sgLDBLRQgZ3fX3oyns0w/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=27406 [article]

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