Analysis of shrinkage development of injection moulded PS samples / R. Pantani in INTERNATIONAL POLYMER PROCESSING, Vol. XIV, N° 2 (06/1999)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIV, N° 2 (06/1999) . - p. 183-190 Titre : Analysis of shrinkage development of injection moulded PS samples Type de document : texte imprimé Auteurs : R. Pantani, Auteur ; G. Titomanlio, Auteur Année de publication : 1999 Article en page(s) : p. 183-190 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Molding - Modern approaches to the phenomenon of dimensional accuracy in injection moulding link the evolution of shrinkage from the moment of first solidification to a force balance between restraining and constraining forces which sets in inside the mould before ejection. Such an approach needs a complete understanding of what happens inside the cavity during the moulding cycle. In a recent paper [9], a new technique has been presented, by which it is possible to follow the shrinkage development of an injection moulded sample from the moment it starts solidifying to soon after ejection. In this work, with reference to a simple rectangular cavity, shrinkage curves measured by strain gages in different moulding conditions are analysed by means of a simple thermomechanical model recently proposed. Results show that the model satisfactorily predicts the moment shrinkage starts inside the mould and reveal the existence of a restraining force not due to pressure, which builds in gradually in a few seconds from the instant of first solidification. Knowing the value of this force - which can be drawn by Hooke's law from the strain jump at mould opening - the model gives a good description of both shrinkage development inside the mould and ejection shrinkage. DOI : 10.3139/217.1529 En ligne : https://drive.google.com/file/d/1zjvr4-f_hNxp_5Pvp9_dXcZeJhnddnvO/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16102 [article]

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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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Evolution of morphology of iPP in processing conditions / I. Coccorullo in INTERNATIONAL POLYMER PROCESSING, Vol. XX, N° 2 (06/2005)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XX, N° 2 (06/2005) . - p. 186-190 Titre : Evolution of morphology of iPP in processing conditions : Relevance of solidification pressure Type de document : texte imprimé Auteurs : I. Coccorullo, Auteur ; G. Titomanlio, Auteur ; R. Pantani, Auteur Année de publication : 2005 Article en page(s) : p. 186-190 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A model for crystallization kinetics that accounts for the formation of different crystalline phases and is able to describe the morphological characteristics of samples solidified under quiescent conditions, has been enriched to account for the effect of solidification pressure. The effect of pressure was considered by assuming a linear increase of melting and glass transition temperatures (which are involved in the description of the growth rate and nucleation density of the alpha phase). Moreover, pressure was incorporated in the kinetic constant adopted to describe the evolution of the mesomorphic phase. The parameters of the model were identified on the basis of literature data on the distribution of crystalline phases in samples solidified under different pressures. The modified model also satisfactorily described PVT curves up to 100MPa, and is now able to describe the evolution of morphology during solidification at cooling rates as fast as several hundreds of Kelvin degrees per second and under pressures of as high as 100MPa. DOI : 10.3139/217.1877 En ligne : https://drive.google.com/file/d/1MU0nmmxwVQ7tBh-DdIgxGkunDd7jIRT1/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3079 [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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Solidification criterion on shrinkage predictions for semi-crystalline injection moulded samples / A. J. Pontes in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 3 (09/2000)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XV, N° 3 (09/2000) . - p. 284-290 Titre : Solidification criterion on shrinkage predictions for semi-crystalline injection moulded samples Type de document : texte imprimé Auteurs : A. J. Pontes, Auteur ; R. Pantani, Auteur ; G. Titomanlio, Auteur ; A. S. Pouzada, Auteur Année de publication : 2000 Article en page(s) : p. 284-290 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The phenomenon of shrinkage in injection moulding is particularly evident in semi-crystalline polymers. During cooling, these materials experience a transition from a completely amorphous to a partially crystalline status, which results in a severe change of all material characteristics, including volumetric parameters. In this study an iPP was injection moulded in a rectangular impression (120mm x 630mm x 62 mm) with a 1.5mm thick line gate. The influence of holding pressure and time, and geometry constraints on linear shrinkage was explored. In-mould shrinkage was measured by means of a recent method based on strain gauges. Experimental results are compared with predictions for shrinkage obtained by C-Mold and a code developed at the University of Salerno, which takes into account crystallisation kinetics. The solidification criterion resulted to be extremely relevant for shrinkage predictions. DOI : 10.3139/217.1594 En ligne : https://drive.google.com/file/d/1ODoaWDUb7LGE1p3TEFUrsf1VD0ZEYdf0/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15833 [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)  

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