On the pressure dependency of the Bagley correction / Peter Van Puyvelde in INTERNATIONAL POLYMER PROCESSING, Vol. XXVIII, N° 5 (11/2013)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVIII, N° 5 (11/2013) Titre : On the pressure dependency of the Bagley correction Type de document : texte imprimé Auteurs : Peter Van Puyvelde, Auteur ; A. Vananroye, Auteur ; A.-S. Hanot, Auteur ; M. Dees, Auteur ; M. Mangnus, Auteur ; N. Hermans, Auteur Année de publication : 2013 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Bagley, Correction de Etat fondu (matériaux) Polycarbonates Pression -- Mesure Rhéologie Rhéométrie Viscosité Index. décimale : 668.4 Plastiques, vinyles Résumé : The effect of pressure on the viscosity of polymer melts is an often forgotten parameter due to the inherent difficulty to measure this quantity. Different experimental approaches have already been undertaken in literature in the past. A popular methodology to measure the pressure dependence of the viscosity is to use a capillary rheometer equipped with a counter pressure chamber in which the exit pressure can be controlled. In order to process the data, one of the key elements is the Bagley correction that is required to determine the correct entrance pressure at a specific shear rate. In all analysis approaches presented in literature on data at controlled exit pressure, the Bagley correction was always de„termined at atmospheric exit pressure, disgarding possible effects of an enhanced exit pressure. In this paper, a new analytical approach is presented that for the first time allows for a direct assessment of the entrance pressures obtained when capillary measurements are performed with controlled counter pressures. It is demonstrated, using polycarbonate, that the entrance pressure correction needed to obtain correct viscosity values under pressure is significantly different than the one needed to correct measurements performed at atmospheric exit pressure. Note de contenu : - MATERIALS AND METHODS - ANALYSIS OF NON-LINEARITIES IN BAGLEY PLOTS WITH AND WITHOUT COUNTER PRESSURE : Bagley plots at atmospheric exit pressure - Bagley plots at elevated exit pressure - EXPERIMENTAL RESULTS : Bagley plots at atmospheric exit pressure - Bagley plots at elevated exit pressures DOI : 10.3139/217.2839 En ligne : https://drive.google.com/file/d/1KYbOEUd1uVr_lWf07y7PZfLM4LgCV5HG/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=19902 [article]

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RheoDSC analysis of hardening of semi-crystalline polymers during quiescent isothermal crystallization / V. Janssens in INTERNATIONAL POLYMER PROCESSING, Vol. XXV, N° 4 (09/2010)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXV, N° 4 (09/2010) . - p. 304-310 Titre : RheoDSC analysis of hardening of semi-crystalline polymers during quiescent isothermal crystallization Type de document : texte imprimé Auteurs : V. Janssens, Auteur ; C. Block, Auteur ; G. Van Assche, Auteur ; B. Van Mele, Auteur ; Peter Van Puyvelde, Auteur Année de publication : 2010 Article en page(s) : p. 304-310 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse thermique Calorimétrie Cristallisation Polymères semi-cristallins Rhéologie Index. décimale : 668.9 Polymères Résumé : The crystallization of semi-crystalline polymers is often analyzed by rheometry and calorimetry. By rheometry the viscosity evolution during crystallization can be followed, whereas from a calorimetric measurement, the evolution of the degree of crystallinity can be calculated. The time evolution of these material properties is valuable input for polymer processing simulation software and in order to combine the data in a reliable manner, hardening curves are used as a characterization tool. Such a hardening curve correlates the relative increase of the viscosity resulting from crystallization, to the advancing degree of crystallinity. In this study, these are extracted from simultaneous measurements on one sample using a RheoDSC device. The RheoDSC technique allows for the direct combination of the rheological and calorimetric signal without the need of combining separate stand-alone measurement results. In this study, isothermal crystallization experiments are used to discuss the benefits of this approach. This will lead to the recommendation that measuring the hardening effect in steady shear measurements at very low shear rates in a direct combined RheoDSC setup is the most reliable method to compile unambiguously a material specific hardening curve for semi-crystalline polymers. DOI : 10.3139/217.2374 En ligne : https://drive.google.com/file/d/1cnJN8rZnm6E-MZMtd51j4BzV5esbC1jN/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=9827 [article]

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The influence of melt and process parameters on the quality and occurrence of part defects in water-assisted injection molded tubes / Sofie Sannen in INTERNATIONAL POLYMER PROCESSING, Vol. XXVI, N° 5 (11/2011)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVI, N° 5 (11/2011) . - p. 551-559 Titre : The influence of melt and process parameters on the quality and occurrence of part defects in water-assisted injection molded tubes Type de document : texte imprimé Auteurs : Sofie Sannen, Auteur ; J. de Keyzer, Auteur ; Peter Van Puyvelde, Auteur Année de publication : 2011 Article en page(s) : p. 551-559 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Epaisseur -- Mesure Matières plastiques -- Moulage par injection Matières plastiques -- Moulage par injection assistée par eau Moulage par injection -- Défauts Plan d'expérience Polyéthylène haute densité Polypropylène Tubes Index. décimale : 668.4 Plastiques, vinyles Résumé : This study investigates the influence of melt and process parameters on the quality of water-assisted injection molded tubes. The influence was determined by the aid of a design of experiments (DOE) for both a HDPE and a PP resin. This design was carried out on two different cavities, in which the residual wall thickness (RWT) and the part weight were set as response functions. This was combined with a visual inspection of the part surface to detect correlations in the occurrence of part defects such as fingering and double wall. It was found that the water injection delay time and the water volume flow rate have the largest influence on the RWT and part weight. Moreover, the shear viscosity of the applied material determines the width and shape of the water bubble and consequently the RWT and part weight. In addition, process parameters such as melt temperature, water hold time and water volume flow rate as well as melt parameters such as shear viscosity have an influence on the formation of part defects. DOI : 10.3139/217.2490 En ligne : https://drive.google.com/file/d/1pAOyM1fM_bc-Cly4qKQsP7EtT8zUFo3j/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12471 [article]

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Water penetration behavior in water-assisted injection molding (WAIM) : A study of product quality for different process and material parameters / Sofie Sannen in INTERNATIONAL POLYMER PROCESSING, Vol. XXVII, N° 5 (11/2012)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVII, N° 5 (11/2012) . - p. 602-616 Titre : Water penetration behavior in water-assisted injection molding (WAIM) : A study of product quality for different process and material parameters Type de document : texte imprimé Auteurs : Sofie Sannen, Auteur ; M. de Munck, Auteur ; Peter Van Puyvelde, Auteur ; J. de Keyzer, Auteur Année de publication : 2012 Article en page(s) : p. 602-616 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Moulage par injection Matières plastiques -- Moulage par injection assistée par eau Moulage par injection -- Défauts Polypropylène Tags : 'Moulage  injection  assisté  eau'  Polypropylène  'Comportement  pénétration  'Epaisseur  paroi  résiduelle'  'Formation  défaut  pièce'  'Mesure  pression  'Débit  volume'  Viscosité  'Fluidité  cisaillement' Index. décimale : 668.4 Plastiques, vinyles Résumé : This study investigates the relation between water penetration behavior and product quality in water-assisted injection molding (WAIM) for different process and material parameters. The principle mechanisms responsible for both building up the residual wall thickness (RWT) and formation of part defects as well as the influence of these process and material parameters on the RWT and occurrence of part defects could be revealed. This is done by relating the measurements of water pressure and water volume flow rate, visualizing in-mold variations during water injection, to both the part weight and a visual inspection of part cross-sections, for different process settings and materials. It was found that the RWT as well as the formation of part defects depend on the polymer resistance, since the variation of the latter leads to a change in both the water bubble width and velocity. On the one hand, the resistance is determined by the process parameters having an influence on the amount of melt ahead of the water bubble, depending on injector opening time, water volume flow rate and water injection delay time. On the other hand, the resistance also depends on the friction between the polymer chains, which is determined by the zero-shear viscosity and the shear thinning behavior of the polymer. In addition, the occurrence of part defects is directly related to the polymer crystallization behavior. The resulting product quality therefore depends on a combination of the process parameters and the applied material. Note de contenu : - EXPERIMENTAL : Material ans set-up - Methodology - RESULTS AND DISCUSSION : Injector opening time - Influence of material parameters DOI : 10.3139/217.2622 En ligne : https://drive.google.com/file/d/1QMi2LZqb5pZ-u5u4ggioD88OQUFJCeov/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16643 [article]

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