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Effects of process conditions on the dissolution of carbon dioxide in PS in foaming extruders / Q. Zhang in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 223-228 Titre : Effects of process conditions on the dissolution of carbon dioxide in PS in foaming extruders Type de document : texte imprimé Auteurs : Q. Zhang, Auteur ; M. Xanthos, Auteur ; S. K. Dey, Auteur Année de publication : 2001 Article en page(s) : p. 223-228 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The effects of the main processing conditions on the dissolution behaviour of CO2 in polystyrene melt were studied using a novel in-line method in connection with both single and twin-screw foaming extruders. Apparent solubility data obtained from the twin-screw extrusion experiments showed better consistency compared with those obtained from single screw experiments, indicating the importance of enhanced mixing in affecting the gas dissolution and solubility behaviour during an extrusion foaming process. Gas dissolution inside a twin-screw foaming extruder was further studied for CO2 in the polystyrene melt. the measured gas up-take was compared with the values calculated assuming equilibrium conditions in the gas injection zone in an effort to elucidate possible mechanisms for gas dissolution inside a foaming extruder during the actual foaming process. Note de contenu : - Solubility of CO2 in polystyrene melt - Effects of processing conditions - Gas dissolution mechanisms inside a foaming extruder DOI : 10.3139/217.1648 En ligne : https://drive.google.com/file/d/14RrCzRQ6uKCPO44bZHM0LVp7o6JP19jH/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15902 [article]

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The design of extrusion screws : an optimization approach / A. Gaspar-Cunha in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 229-240 Titre : The design of extrusion screws : an optimization approach Type de document : texte imprimé Auteurs : A. Gaspar-Cunha, Auteur ; Jose A. Covas, Auteur Année de publication : 2001 Article en page(s) : p. 229-240 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The design of a screw for plasticating polymer extrusion based on scientific principles is still a challenging task, which has received surprisingly little attention in the literature. In the present work the design of a screw is considered as an optimization problem. The corresponding design methodology is discussed. Two alternative approaches are considered. In the first case, the aim is to maximize the value of an objective function that describes quantitatively the process performance in terms of pre-selected important process criteria. A multiobjective optimization scheme resorting to the use of optimal or non-dominated Pareto frontiers is also implemented, where the set of feasible individual solutions in terms of the various criteria is correlated, thus evidencing the compromise between them. The relevance of the solutions and the sensitivity of the method to changes in the criteria considered are demonstrated with a case study. Note de contenu : OPTIMISATION METHODOLOGY - SCREW DESIGN METHODOLOGY - EXTRUSION MODELLING : Solids conveying in the hopper - Solids conveying in the screw - Delay zone - Melting zone - Melting conveying - Melt flow - SCREW DESIGN : Case study - Optimisation with objective function - multi-objective optimisation DOI : 10.3139/217.1652 En ligne : https://drive.google.com/file/d/1iekq7n2TgRFI9F7SRQIJ5FNXxGs_bSA2/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15903 [article]

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Generalized flow of Ellis fluid in the screw channel / R. T. Steller in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 241-248 Titre : Generalized flow of Ellis fluid in the screw channel : Part I : Parallel plates model Type de document : texte imprimé Auteurs : R. T. Steller, Auteur ; J. Iwko, Auteur Année de publication : 2001 Article en page(s) : p. 241-248 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Analytical expressions for the isothermal, two-dimensional flow of an Ellis fluid in rectangular channel have been derived. The obtained solution describes also the flow of Newtonian and power law fluids as the specific cases. This solution was further adapted for the theoretical analysis of the temperature and pressure effects during the non-isothermal flow of Ellis fluid. the results obtained both for isothermal an non-isothermal flow conditions have been verified numerically. DOI : 10.3139/217.1649 En ligne : https://drive.google.com/file/d/1gYdLjj9xN1NXqF1DXewWR-73GKqeBxUo/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15904 [article]

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Generalized flow of Ellis fluid in the screw channel / R. T. Steller in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 249-256 Titre : Generalized flow of Ellis fluid in the screw channel : Part II : Curved channel model Type de document : texte imprimé Auteurs : R. T. Steller, Auteur ; J. Iwko, Auteur Année de publication : 2001 Article en page(s) : p. 249-256 Note générale : Bilbliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Analytical model for the isothermal and non-isothermal, two-dimensional flow of an Ellis fluid in curved channel has been proposed. It describes also the flow of Newtonian and power law fluids as the specific cases. The solution basing on cylindrical coordinates to account the effect of channel curvature on the flow. the results obtained for isothermal and non-isothermal flow conditions have been verified numerically. DOI : 10.3139/217.1650 En ligne : https://drive.google.com/file/d/1TXK_Wm1bqJfywNwOOJ0SAtqO8Z6cR4So/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15905 [article]

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Experimental study of melting in an intermeshing counter-rotation twin screw / Krzysztof J. Wilczynski in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 257-262 Titre : Experimental study of melting in an intermeshing counter-rotation twin screw Type de document : texte imprimé Auteurs : Krzysztof J. Wilczynski, Auteur ; J. L. White, Auteur Année de publication : 2001 Article en page(s) : p. 257-262 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : An experimental study is presented of the melting mechanism in a starve fed closely intermeshing counter-rotating twin screw extruder of a modular Leistritz design. Polypropylene and low density polyethylene as well as different screw configurations of thick flighted and thin flighted elements were investigated, at various operating conditions. A "Screw Pulling-out Technique" was used to characterize polymer behaviour along the screw axis. In particular, the solid conveying, melting positions, the extent of starved character along the screw, and the fully filled region were observed. Polymer samples were stripped off from each screw which was removed from the machine to investigate melting mechanism. Generally, it was concluded that the melt mechanism consists of pellets being dragged into the calendering gap where they are melted due to calendering action. In the case of thick flighted screws, the molten polymer is expelled from the gap and pushes against the pellet bed which is continuously dragged into the gap. Note de contenu : - General observations - Influence of screw configuration (Screw configuration A, Screw configuration B, Screw configuration C - Influence of operating conditions (Flow rate, Screw speed, Effect of material) - Examination of carcasses - DISCUSSION : Observations related to scew fill - Melting DOI : 10.3139/217.1645 En ligne : https://drive.google.com/file/d/112o1R9BqvU1FAsmcZoyK9h82VyvVISex/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15906 [article]

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A dynamic model for multiple steady states in reactive extrusion / L. P. B. M. Janssen in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 263-271 Titre : A dynamic model for multiple steady states in reactive extrusion Type de document : texte imprimé Auteurs : L. P. B. M. Janssen, Auteur ; P. F. Rozendal, Auteur ; M. Cioffi, Auteur ; H. W. Hoogsrtaten, Auteur Année de publication : 2001 Article en page(s) : p. 263-271 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The existence of multiple stationary values of the fully filled length in reactive extrusion is studies on the basis of a mathematical model describing extruder behavior. The extruder is modelled as a plug flow type of reactor. Through the introduction of travel time for a fluid element in the extruder, time dependent viscosity models following from rheokinetics can be used. Special attention is paid to ionic and radical polymerization reactions. Hysteresis behavior for stationary values of the fully filled length exists when die resistance and rotational speed are varied. The effects of reaction rate, viscosity levels and degree-of-fill on stable operation at high conversions are studied. The mathematical dynamic model presented here can account for some of the experimentally observed dynamic phenomena in the reactive extrusion of radical polymers. Note de contenu : - MATHEMATICAL FORMULATION : Fluid dynamical aspects - The concept of travel time - Overview of the model - RESULTS : Isoviscous case - Rheokinetic approach for polyaddition reactions - Rheokinetic approach for ionic and radical polymerisation (Influence of the rheonkinetic parameter n, Influence od rotational speed N, Influence of die resistance Kd, Influence of the viscosity ratio ninfini/n0, Influence of the reaction rate gamma, Influence of the leakage gaps in teh partially filled zone DOI : 10.3139/217.1651 En ligne : https://drive.google.com/file/d/10R6T5J1iLndNTOjFo8MucZEhX_XWowWJ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15907 [article]

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PA612 double bubble tubular film process - Processability and structure development / S. Rhee in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 272-284 Titre : PA612 double bubble tubular film process - Processability and structure development Type de document : texte imprimé Auteurs : S. Rhee, Auteur ; J. L. White, Auteur Année de publication : 2001 Article en page(s) : p. 272-284 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Biaxially oriented Polyamide 612 (PA612) films made by double bubble tubular film extrusion were characterized. The processing characteristics of the polymer in the double bubble process were investigated. The development of crystallinity and orientation in the films was clearly considered. First bubble PA612 films showed a low level of crystallinity (X = 7.7 %). Differential scanning calorimetry (DSC) indicated that the first bubble PA 612 films experienced a considerable increase in glass transition temperature (Tg), cold crystallization temperature (Tc) and crystallinity during aging at room conditions. The second bubble films were more highly crystalline (X = 22 to 28 %) with poorly grown β unit cells. The WAXD and SAXS patterns showed that the crystallites of double bubble PA612 films became more perfect by annealing in a boiling 20 % formic acid solution, resulting in a well-developed triclinic α crystals coexisting with minor proportion of β phase. the WAXD and SAXS patterns indicated that crystallographic planes and lamellae in the second bubble films were oriented depending on SBUR x SDDR (second blow-up ratio x second draw down ratio). White-Spruiell biaxial orientation factors were calculated with the WAXD pole figure data. The hydrogen bonding (0k0) planes of biaxial double bubble films were found by WAXD to be aligned parallel to the sheet surface before and after annealing. Note de contenu : - EXPERIMENTAL : Material - Film formation - Annealing - Film characterization (Differential scanning calorimetry DSC, Wide angle X-RAY diffraction WAXD flat film patterns and pole figures, Infrared IR spectroscopy, Small angle X-RAY diffraction SAXS) - RESULTS : Bubble stability - Differntial scanning calorimetry DSC - WAXD flat film patterns - IR (Infrared) spectroscopy - Pole figures - Small angle X-RAY diffraction SAXS - DISCUSSION : Bubble stability - Thermal properties - Crystal structure - IR spectroscopy - Orientation factors - Crystal superstructure DOI : 10.3139/217.1647 En ligne : https://drive.google.com/file/d/1anPOZPYobL1ryPHNEB7CjO5Gq95O1H9t/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15908 [article]

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Injection molding technology for high speed optical disk / S. J. Park in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 285-290 Titre : Injection molding technology for high speed optical disk Type de document : texte imprimé Auteurs : S. J. Park, Auteur ; S. K. Kim, Auteur ; T. H. Kwon, Auteur ; K. H. Yoon, Auteur Année de publication : 2001 Article en page(s) : p. 285-290 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Recently great efforts have been made to increase the data access speed and the data storage density of the optical memory disks such as CD-ROM, DVD, ASMO disk, etc. In the viewpoint of increasing the data access speed of the optical disks, it is of great importance to characterize accurately the vibration phenomena of the rotating disk, which is related to the critical speed and the characteristics of the frequency response. In this paper, towards the goal of increasing the data access speed of the optical disks, we have proposed a novel method for improved characteristics of disk vibration without deteriorating any other specification for the optical memory disks such as geometrical and optical characteristics. A possible idea to improve the vibration characteristics of the optical disk is that the tensile initial stress in the radial direction is to be imposed within the optical disk on purpose. By the synergy effect from the residual (initial) tensile stress frozen within the optical disk combined with the stress induced by the centrifugal force occurring in rotating the optical disk, the stiffness of the disk would increase to have a stronger resistance to the disturbance resulting in increase of critical speed. With such a synergy effect in mind, modifications related to the optical disk substrate design, injection mold design and processing conditions of injection molding were presented and partially evaluated. The computer simulation and experiments indicate that the suggested ideas clearly improve the characteristics of disk vibration without deteriorating any other specification for the optical memory disks. Note de contenu : - FEASIBILITY STUDY I : VIBRATION CHARASTERISTICS OF THE OPTICAL DISKS : Modal frequencies and FRF characteristics - Disk rotating and critical speeds - Initial stress effects - FEASIBILITY STUDY II : INJECTION MOLDING OF THE OPTICAL DISK - EXPERIMENTAL VERIFICATIONS DOI : 10.3139/217.1644 En ligne : https://drive.google.com/file/d/1p4KUT-q5sMcDjZCf9ZLJRQcIALGoPh3t/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15912 [article]

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Three-dimensional filling and post-filling simulation of polymer injection molding / F. Ilinca in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 291-301 Titre : Three-dimensional filling and post-filling simulation of polymer injection molding Type de document : texte imprimé Auteurs : F. Ilinca, Auteur ; J.-F. Hétu, Auteur Année de publication : 2001 Article en page(s) : p. 291-301 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : This paper presents a finite element solution algorithm to solve polymer injection molding problems. The methodology solves the momentum, mass and energy conservation equations in three-dimensions. Packing and cooling stages of the injection molding process are modeled by considering compressibility effects. The procedure is aimed at processes in which three-dimensional effects are important. The method is also shown to be effective for thin parts. The performance of the proposed approach is measured on the injection of a plate for which experimental data are available. The procedure is also applied to a thick 3D part. The method results in accurate solutions and it is a useful tool to quantify the material behaviour on cases otherwise difficult to investigate. Note de contenu : - GOVERNING EQUATIONS : Flow and heat transfer equations - Compressibility modeling - Tracking of the polymer flow front during filling - Frozen layer and shrinkage computation - SOLUTION ALGORITHM : Momentum-continuity equations - Energy equation - Front tracking equation - NUMERICAL RESULTS : Filling and post-filling analysis of a plate (Material properties, State equation, Numerical situations) - Packing simulation for a car door handle DOI : 10.3139/217.1643 En ligne : https://drive.google.com/file/d/1M8PaqJMLWGmtzEOlNvIZGakWe6dZDVAn/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15913 [article]

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Microstructure and prediction of stress-strain behaviour of cold-rolled PP sheets / S. Z. Wu in INTERNATIONAL POLYMER PROCESSING, Vol. XVI, N° 3 (09/2001)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XVI, N° 3 (09/2001) . - p. 302-308 Titre : Microstructure and prediction of stress-strain behaviour of cold-rolled PP sheets Type de document : texte imprimé Auteurs : S. Z. Wu, Auteur ; W. B. Lee, Auteur Année de publication : 2001 Article en page(s) : p. 302-308 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A constitutive equation for cold-rolled polypropylene is presented based on a modified two-phase model for semicrystalline polymer, which combines the crystalline network that obeys the Langevin based theory and the entangled network with slip-linked character. The microstructure of the rolled semicrystalline polymer consists of packed crystalline inclusions which are separated by adjacent amorphous regions. A theoretical description of the stress strain behaviour is obtained by the sum of the stress effects from crystalline and entangled networks. The microstructural observation by scanning electron microscopy, X-ray pole figures and differential scanning calorimetry show that polymer chains are aligned along the rolling direction. The stress-strain equation can be obtained from the modified two-phase model and verified by experimental results. Note de contenu : -THEORETICAL STUDY : Modified two phase model - Theoretical two-phase model - Theoretical study (Crystalline network, Stress from crystalline network, Stress from entangled network - EXPERIMENTS AND RESULTS : Experiments (Sample preparation, Scanning Electron Microscopy SEM, X-Ray pole figure, Differential scanning calorimetry DSC, Mechanical properties) - Microstructures - Comparison od stress-strain equation with experimental results DOI : 10.3139/217.1646 En ligne : https://drive.google.com/file/d/1cgFJy0nWebM88Z4aK_5SXkSFWPpqEOWS/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=15914 [article]

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