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Ajouter le résultat dans votre panierThe dynamic apparent viscosity of polymer melts during pulsatile extrusion flow with vibration force field / G.-J. He in INTERNATIONAL POLYMER PROCESSING, Vol. XXIII, N° 1 (03/2008)
Titre : The dynamic apparent viscosity of polymer melts during pulsatile extrusion flow with vibration force field : Theory and experiment Type de document : texte imprimé Auteurs : G.-J. He, Auteur ; X.-C. Yin, Auteur ; J.-P. Qu, Auteur Année de publication : 2008 Article en page(s) : p. 2-7 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Extrusion:Polymères -- Extrusion
Polypropylène
Rhéologie
Rhéomètres
ViscositéIndex. décimale : 668.9 Polymères Résumé : The dynamic apparent viscosity of polymer melts during pulsatile extruding flow with a vibration force field was studied on a self-made dynamic capillary rheometer (DCR). A theory that could reflect the vibration influence on the dynamic apparent viscosity was proposed. Due to the superposition of the vibration force field upon the steady shear flow, the phase difference between the shear stress and the shear rate could be chosen as a parameter to reflect the effect of vibration on the dynamic apparent viscosity. According to this theory, the average shear rate during pulsatile extrusion increased because of the existence of the phase difference, which caused the decrease of the dynamic apparent viscosity. The experimental results proved that the phase difference was reduced with the increase of vibration frequency, which resulted in a decrease in the dynamic apparent viscosity during the pulsatile extrusion. DOI : 10.3139/217.0002 En ligne : https://drive.google.com/file/d/1TtXJ7siyZ2rKogu1f7aVP0YkeuXfjF6C/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2654
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Titre : Generation of microcellular foams by supercritical carbon dioxide in a PMMA compound Type de document : texte imprimé Auteurs : K. Y. Kim, Auteur ; S. L. Lang, Auteur ; H.-Y. Kwak, Auteur Année de publication : 2008 Article en page(s) : p. 8-16 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matériaux poreux
Mousses plastiques
Polyméthacrylate de méthyleLe poly(méthacrylate de méthyle) (souvent abrégé en PMMA, de l'anglais Poly(methyl methacrylate)) est un polymère thermoplastique transparent obtenu par polyaddition dont le monomère est le méthacrylate de méthyle (MMA). Ce polymère est plus connu sous son premier nom commercial de Plexiglas (nom déposé), même si le leader global du PMMA est Altuglas International9 du groupe Arkema, sous le nom commercial Altuglas. Il est également vendu sous les noms commerciaux Lucite, Crystalite, Perspex ou Nudec.Index. décimale : 668.9 Polymères Résumé : Decompression experiments from a PMMA compound saturated with CO2 at high pressure were performed to investigate the heterogeneous effect due to the aggregate of the additives on the microcellular foam structure generated. The observed results were compared with calculation results from a previously proposed homogeneous nucleation model. Uniform distribution of foams was obtained at a lower temperature of T = 20°C at various initial pressures tested. However, the heterogeneous effect due to the aggregate of the additives in the compound occurred at the solution temperature of T = 40°C, which is quite different from the results obtained in PMMA/CO2 solution where homogeneous nucleation occurs in the temperature range between 40°C and 70°C. Experimental results obtained in this study may be applied to the injection-molding process of PMMA compounds. DOI : 10.3139/217.0027 En ligne : https://drive.google.com/file/d/1CADWQfIJMfh37sx4Pn_fmHnTgnVLv12q/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2655
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Titre : Influence of uniaxial extension on the mechanical properties of PET and PEN films Type de document : texte imprimé Auteurs : J. H. Wang, Auteur ; J. H. Kim, Auteur ; H. J. Kang, Auteur ; F. E. Talke, Auteur Année de publication : 2008 Article en page(s) : p. 17-23 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Films plastiques -- Propriétés mécaniques
Polyéthylène naphtalate
Polyéthylène téréphtalateIndex. décimale : 668.9 Polymères Résumé : The modulus and hardness of poly(ethylene terephthalate)-(PET) and poly(ethylene naphthalate)(PEN) films are studied as a function of the uniaxial draw ratio using nanoindentation and macro-scale tensile testing equipment. Nanoindentation tests were conducted in the machine-transverse plane, the transvers-normal plane, and the machine-normal plane of the PET and PEN films to determine mechanical properties (hardness and modulus of elasticity) of the uniaxially stretched films at the nano-scale. The films were then re-tested using a tensile tester to determine the modulus on the macro-scale. The results from the two methods show large differences. Birefringence measurements indicate that the macro-scale and nano-scale moduli are strongly influenced by the chain orientation after uniaxial stretching. In addition, the influence of chain orientation is found to be much larger on the macro-scale than on the nano-scale. DOI : 10.3139/217.1002 En ligne : https://drive.google.com/file/d/1KPZxPsTGSWHcTKs1Af5Np4No01oiOWx6/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2656
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Titre : Analysis of the isothermal compression in nanoimprint lithography assuming a power-law fluid Type de document : texte imprimé Auteurs : I.-C. Hsin, Auteur ; W.-B. Young, Auteur Année de publication : 2008 Article en page(s) : p. 24-29 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : One of the choices for defining a nano pattern in micro fabrication is to use the nanoimprint lithography. This method is also known as a hot embossing lithography due to its inherited process technique from the compression process. It is important to determine the appropriate conditions of pressure, temperature, and time in the nanoimprint lithography process. To determine the right conditions for nanoimprint lithography, one has to understand the polymer flow behavior during the imprinting process. In this study, a simplified analytical model was developed based on a power-law fluid to predict the polymer flow during the imprinting process. Under a constant imprint force, the imprint depth on a polymer film can be predicted using this model. Experimental tests were also conducted to verify the results. It was demonstrated that the model can provide reasonable results on the imprint depth. DOI : 10.3139/217.1008 En ligne : https://drive.google.com/file/d/1YVKt8BLd5pJKB0euqx0Ysd-Puu3PiC8a/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2657
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Titre : Non-isothermal simulation of the film blowing process using multi-mode extended pom-pom model Type de document : texte imprimé Auteurs : S. Sarafrazi, Auteur ; F. Sharif, Auteur Année de publication : 2008 Article en page(s) : p. 30-37 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Plastic films are largely produced using the film blowing process. Branched polymers such as LDPE are commonly used in this process to produce a variety of plastic films. In this study, recently developed eXtended Pom-Pom (XPP) model, which focuses on describing rheological behavior of branched polymers, is employed to analyze the non-isothermal flow in the film blowing process. Furthermore, the Nakamura equation for crystallization kinetics is employed to consider crystallization effects and improve prediction of the state of the stress in the film. Results of the numerical analysis show good agreement with the experimental values reported by Tas (1994) for the bubble shape and film velocity of the LDPE films. Predictions for the strain rates in machine and hoop directions which are critical for the estimation of the stress are also compared with the reported data and showed reasonably good agreement. DOI : 10.3139/217.2010 En ligne : https://drive.google.com/file/d/1WwcTXyLhP4FF-rCDlV-ePQgC4JeyQJT3/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2658
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Titre : Flow analysis of flat spiral dies and comparison with cylindrical spiral mandrel dies Type de document : texte imprimé Auteurs : M. Malekzadeh, Auteur ; F. Goharpey, Auteur ; Reza Foudazi, Auteur Année de publication : 2008 Article en page(s) : p. 38-46 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Cylindrical Spiral Mandrel Dies (SMD) and Flat Spiral Dies (FSD) are widely used in blown film co-extrusion processes. Although in recent years the use of stackable (flat) spiral dies in the blown film extrusion has been continuously growing, a phenomenological study on designing parameters of this type of dies, and comparison of their flow distribution with SMD has not been made yet. In this work, the flow of a viscous power law fluid in a typical flat spiral die, based on Rauwendaal's method (1987) for analyzing cylindrical spiral mandrel dies, has been investigated. Validation of this method for flat spiral dies was confirmed by comparison with the results reported using the finite element method. The effects of some design parameters, such as number of grooves, initial flight clearance, initial groove depth, on pressure gradient, flow distribution and other operational variables have also been studied. It has been found that the flow distribution becomes more uniform with increasing number of grooves, initial groove depth and coefficient of Archimedes type flat spiral. Moreover, the results have shown that the increment of the clearance angle between two die plates, as well as the initial clearance, have an optimum value in which the flow distribution is the most uniform. Finally, flow variations in FSD and SMD have been compared for different design parameters. The results demonstrated that the melt flow distribution at the outlet of the cylindrical spiral mandrel die is more uniform, while the pressure loss of the flat spiral die is lower. DOI : 10.3139/217.2018 En ligne : https://drive.google.com/file/d/10yttjsekKkuX4Y4YTAQbi-rxgqrqGkt6/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2659
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Titre : Development of polymer blend morphology along an extruder with different screw geometries Type de document : texte imprimé Auteurs : H.-X. Huang, Auteur ; G. Jiang, Auteur ; X.-J. Li, Auteur Année de publication : 2008 Article en page(s) : p. 47-54 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The morphology development of an immiscible polymer blend along a single screw extruder was investigated, concentrating on the effect of screw geometry. Three different screw geometries were evaluated: one with conventional screw elements; the other two with a fluted and Pineapple mixing element, respectively. The experiments were conducted using a polypropylene/polyamide-6 (PP/PA 6) blend. The blend samples were collected from four different positions using specially designed sampling device along the extruder online during blending and were then examined using scanning electron microscopy. The experimentally observed morphology evolution was evaluated both qualitatively, in terms of spatial distribution of dispersed phase, as well as quantitatively, by analysis for the size of the dispersed phase. The morphology development was interpreted with the aid of the flow fields occurring along screw elements. The results showed that the screw with conventional screw elements produce the coarsest and most non-uniform morphology whereas the screw with a fluted mixing element appears to produce the finest and most uniform morphology at the end of the extruder. The Pineapple mixing element, with a characteristic of chaotic mixing, facilitates to form thinner laminar layers of dispersed phase. The experimentally observed morphology difference between the conventional and fluted mixing element was demonstrated by the simulation. DOI : 10.3139/217.2019 En ligne : https://drive.google.com/file/d/17cNDlyzikWzIo2fAlj47c1AADvYRtW6A/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2660
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Titre : A mechanical model for stress development in PA12 tube extrusion : Application to structure development Type de document : texte imprimé Auteurs : Jean-Marc Haudin, Auteur ; A. Carin, Auteur ; O. Parant, Auteur ; A. Guyomard, Auteur ; M. Vincent, Auteur ; C. Peiti, Auteur ; F. Montezin, Auteur Année de publication : 2008 Article en page(s) : p. 55-64 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : In polyamide 12 tube extrusion, calibration is the key step of the process that affects the subsequent mechanical properties. In previous work it has been shown that according to the calibration conditions, a very oriented skin layer may be created, which has been correlated to an important decrease of elongation at break. In the present paper we develop a thermomechanical model which consists of two parts: a viscoelastic mechanical model for the calculation of stresses and a thermal model for the determination of the temperature field. Three types of inputs are necessary: processing parameters, material data (e.g., crystallization kinetics and rheology in the melt, the solid state and the transition zone) and heat transfer coefficients to describe the heat exchanges along the extrusion line. The model allows us to propose a physical interpretation of the oriented layer. During cooling high axial stresses are frozen in the first solidified layers. They induce a plastic deformation of the polymer leading to a high level of orientation in the outer zones. DOI : 10.3139/217.2028 En ligne : https://drive.google.com/file/d/1YoC1MG1nXG7_8l1EUjuu5HPDYF_fD0yI/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2661
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Titre : Shrinkage analysis on convex shell by injection molding Type de document : texte imprimé Auteurs : C.-C. Chen, Auteur ; S.-W. Chang, Auteur Année de publication : 2008 Article en page(s) : p. 65-71 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Moulage par injection Index. décimale : 668.9 Polymères Résumé : Injection molding of a convex shell has induced divergent flow front directions and therefore the shrinkage of a convex shell is difficult to controll. In some optical applications, such as ophthalmic devices of soft contact lens, that can be cast molded with a set of two convex shells made by injection molding there is a demand in maintaining dimensional stability. This research investigates the optimization of injection molding parameters for the minimum shrinkage of a convex shell of polypropylene (PP). The MPI 5.0 software is used first to simulate the filling stage of the convex shell and find the feasible operational ranges of parameters. Experiments were performed by an electric injection machine. Short shot experiments have been tested to compare with results of mold flow simulation. Taguchi's method is then used to find the optimal parameters for the minimum shrinkage of convex shell. Four parameters or factors, including mold temperature, injection temperature, holding pressure, and cooling time are considered in this study. An ANOVA table has been obtained for checking the significance of parameters. Results of simulation and experiments have been compared and the holding or packing pressure is found as the most significant parameter for the minimum shrinkage of a convex shell. Cooling time and injection temperature have been found as the second and third most significant parameters in this study. The optimal parameters have been established and then verified by the optimal injection molding experiment and the minimum shrinkage of convex shell was obtained as 72 µm. DOI : 10.3139/217.2044 En ligne : https://drive.google.com/file/d/1XtzqP8KvKDpCccG4AiYYlfm1AnFNmBlI/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2662
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Titre : Melting mechanism of thermoplastic elastomers and comparison to polyolefin thermoplastic melting studies in a single screw extruder Type de document : texte imprimé Auteurs : W.-J. Lu, Auteur ; S. H. Bumm, Auteur ; J. L. White, Auteur Année de publication : 2008 Article en page(s) : p. 72-80 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Elastomères thermoplastiques
Extrudeuse monovis
PolyoléfinesUne polyoléfine, parfois appelée polyalcène, désigne un polymère aliphatique saturé, synthétique, issu de la polymérisation d'une oléfine (aussi appelée un alcène) telle l'éthylène et ses dérivés.
La formule générale est -(CH2-CRR')n-, où R et R' peuvent être l'atome d'hydrogène (H) ou les radicaux alkyle apolaires CH3, CH2-CH3, CH2-CH(CH3)2. Il existe aussi des mousses isolantes souples faites à partir de polyoléfine (pour l'isolation thermique de tuyaux plastiques par exemple).
PRESENTATION : Les polyoléfines forment la plus importante famille de matières plastiques, avec quatre représentants (PP, HDPE, LDPE, LLDPE) parmi les plastiques de grande consommation. La consommation mondiale de ces quatre polymères est évaluée à plus de 60 millions de tonnes en 20001.
Seul un petit nombre de polyoléfines a atteint le niveau industriel :
les polyoléfines thermoplastiques semi-cristallines : polyéthylène (PE), polypropylène (PP), polyméthylpentène (PMP), polybutène-1 (PB-1) ;
les polyoléfines élastomères : polyisobutylène (PIB), éthylène-propylène (EPR ou EPM) et éthylène-propylène-diène monomère (EPDM).
PROPRIETES : En raison de leur nature paraffinique, les polyoléfines sont hydrophobes et possèdent en général une grande inertie chimique (aux solvants, acides, bases, etc.). Ces matériaux ont donc une qualité alimentaire. Le collage est très difficile (la surface est particulièrement inerte, des traitements de surface spéciaux sont nécessaires).
Cependant, ils sont sensibles à l'action des UV, et résistent très peu à l'inflammation car leur indice limite d'oxygène est faible (exemple : ILO ~ 17 pour le polyéthylène).
Leur densité est très faible [0,83 (cas du PMP) < d < 0,95] : ils flottent dans l'eau.
Ils sont opaques, sauf le PMP (transparent).
ThermoplastiquesUne matière thermoplastique désigne une matière qui se ramollit (parfois on observe une fusion franche) d'une façon répétée lorsqu'elle est chauffée au-dessus d'une certaine température, mais qui, au-dessous, redevient dure. Une telle matière conservera donc toujours de manière réversible sa thermoplasticité initiale. Cette qualité rend le matériau thermoplastique potentiellement recyclable (après broyage). Cela implique que la matière ramollie ne soit pas thermiquement dégradée et que les contraintes mécaniques de cisaillement introduites par un procédé de mise en forme ne modifient pas la structure moléculaire.Index. décimale : 668.9 Polymères Résumé : An experimental investigation of the mechanisms of melting of various thermoplastics elastomers (TPEs) in single screw extruder was carried out under different operating conditions. The TPEs included three polypropylene vulcanized EPDM (TPV) thermoplastic elastomers and two styrene-hydrogenated butadiene block copolymer. The results were compared to new and earlier experimental investigations of the melting of polyethylene and polypropylene. We also characterized the shear viscosity of all polymer melts studied. The TPEs all exhibited yield values in shear flows. To characterize the melting process in a single screw extruder, we used a flow marker procedure which consists of introducing pigments with the neat pellets. This is a technique originally developed by Maddock (1959). At the steady state, we abruptly stopped the extruder operation, cooled the barrel and pushed the screw from the barrel. The polymer carcasses were stripped from the screws and slices cross-sectioned every turn from the hopper to die were photographed and evaluated, and the melting mechanism was determined. The results for the TPEs exhibit significant differences from the crystalline polyolefin. DOI : 10.3139/217.2043 En ligne : https://drive.google.com/file/d/1oc0ZhGASfvZJmrhL5JfFzt_xEwDw3df1/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2663
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Titre : Thermal degradation of meta and para-aramid fibers in different atmospheres Type de document : texte imprimé Auteurs : X.-W. Wang, Auteur ; Z.-M. Hu, Auteur ; Z.-F. Liu, Auteur Année de publication : 2008 Article en page(s) : p. 81-87 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The thermal degradation behavior of meta- and para-aramid fibers (PMIA and PPTA) in different atmospheres was studied by thermogravimetric analysis coupled with mass spectrometry (TGA-DTA/MS). The process of mass loss in the degradation of PMIA was divided into three steps in both argon and air. The mass loss of PPTA was greater than that of PMIA in argon when the temperature reached 1000°C. Simultaneous TG/DTA measurements showed that the thermal degradation was endothermic in argon and exothermic in air for both fibers. Mass spectra of volatiles were obtained, and PMIA and PPTA gave similar mass signals. The temperatures of maximum abundances in ion currents corresponded to the temperatures of mass loss peaks in the DTG curves. The relative values of ion currents were compared at various temperatures. The yield of CO2 was the largest fraction in ion currents of all the volatiles, and the abundances of ion currents of phenyl compounds were low. The elemental analyses of decomposed PMIA and PPTA fibers provided direct information of chemical and morphological changes. A synthetic kinetic model was introduced, and the analyses of kinetic parameters were used to explain the degradation progresses. DOI : 10.3139/217.2046 En ligne : https://drive.google.com/file/d/15er98h5erwkdQ9_J22m4SqBrxWWDpj0W/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2664
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Titre : Experimental studies on screw characteristics in closely intermeshing counter-rotating twin screw extruder Type de document : texte imprimé Auteurs : M.-H. Hong, Auteur ; Q. Jiang, Auteur ; J. L. White, Auteur Année de publication : 2008 Article en page(s) : p. 88-92 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Experimental Studies on Screw Characteristics in Closely Intermeshing Counter-rotating Twin Screw Extruder DOI : 10.3139/217.2049 En ligne : https://drive.google.com/file/d/1gceJ67CNLhTKJAt-yA1OYiPB4SpN6Gk-/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2665
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Titre : Experimental analysis of heat transfer in rotational molding process Type de document : texte imprimé Auteurs : Vincent Sobotka, Auteur ; Estelle Perot, Auteur ; Abderrahim Maazouz, Auteur ; D. Delaunay, Auteur Année de publication : 2008 Article en page(s) : p. 93-102 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Rotational molding is a process by which powdered or liquid plastics are converted into hollow articles. This process is relatively simple in a technical point of view but it involves very complex physical phenomena. Constant quality in technical parts requires the mastery of the process by controlling on line these phenomena. One of these of first importance is heat transfer. This paper concerns the experimental analysis of heat transfer in rotational molding process with semi-crystalline polymer. By using an instrumented mold associated with an original radio transmission data acquisition system, we demonstrate that the rotational nature of the process implies complex heat transfer evolutions in the mold. The crystallization of the material is modeled with accuracy by coupling heat transfer equation to a kinetic model determined by calorimetry. It appears that thermal contact resistance evolution is a key point of heat transfer during the solidification of the polymer. DOI : 10.3139/217.2064 En ligne : https://drive.google.com/file/d/1fR4IBxGTnROyPoybuO7I2jQVyQhasFZa/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2666
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Titre : Polyetheretherketone films with low thermal expansion for flexible printed circuit boards Type de document : texte imprimé Auteurs : C. Seidel, Auteur Année de publication : 2008 Article en page(s) : p. 103-109 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Rigid and flexible circuit boards consist of layers of different materials. Particularly, the different thermal expansion coefficients of thermoplastic polymers and metals can lead to problems during application. The investigations presented are focused on the high-temperature thermoplastic polyetheretherketone (PEEK), as it has a remarkable potential for novel flexible circuit boards. The work shows the significant thermal expansion reductions that can be reached in a thermoplastic polyetheretherketone (PEEK) film by the incorporation of different contents of calcium carbonate or talc fillers and compares their effectiveness. Particularly the influence of filler geometry on the thermal expansion is studied in detail. The effect of the filling on mechanical properties and the dimensional stability of the PEEK films under thermal load is investigated quantitatively. DOI : 10.3139/217.2080 En ligne : https://drive.google.com/file/d/1XMXXLHTYQP8Ak3K6uOoSaYsw5PxbJuyJ/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2667
in INTERNATIONAL POLYMER PROCESSING > Vol. XXIII, N° 1 (03/2008) . - p. 103-109[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 009860 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Experimental study and modeling of flow behavior and orientation kinetics of layered silicate/polypropylene nanocomposites in start-up of shear flows Type de document : texte imprimé Auteurs : M. Rajabian, Auteur ; Ghasem Naderi, Auteur ; M. H. Beheshty, Auteur ; P. G. Lafleur, Auteur ; C. Dubois, Auteur ; P. J. Carreau, Auteur Année de publication : 2008 Article en page(s) : p. 110-118 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Effects of organoclay contents on the startup flow properties of layered nano-scale particles in the simple shear mode are investigated. The addition of small amounts of nanoclays to polypropylene melts was found to dramatically change the flow characteristics and creates stress overshoots at large shear rates. A rheological model, initially developed for studying the motion of a group of symmetric ellipsoid particles in viscoelastic fluids was used to describe the orientation state of the uniformly dispersed suspensions of layered silicate in polypropylene melts. The effects of shear, particle loadings, particle interactions, flow reversal and rest time after cession of shear are studied and discussed according to our experimental observations and model predictions. It is shown that another diffusion term in the governing equation for the particles can be used to predict the properties by applying the rest time which was found to change the orientation of particles and shifts it to more isotropic microstructures. The experimental results of the startup viscosity are reasonably well predicted by the model at the three shear rates tested. DOI : 10.3139/217.2101 En ligne : https://drive.google.com/file/d/1ok-ZCaQwUOhb8PghLdMll78eJbMBs4VP/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2668
in INTERNATIONAL POLYMER PROCESSING > Vol. XXIII, N° 1 (03/2008) . - p. 110-118[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 009860 - Périodique Bibliothèque principale Documentaires Disponible
Titre : Polystyrene/phosphonium organoclay nanocomposites by melt compounding Type de document : texte imprimé Auteurs : J. U. Calderon, Auteur ; B. Lennox, Auteur ; Musa R. Kamal, Auteur Année de publication : 2008 Article en page(s) : p. 119-128 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Polystyrene-montmorillonite nanocomposites were prepared by melt compounding, using several ammonium and phosphonium organoclays. Melt processing was carried out in a twin screw extrusion system, specially modified to produce improved dispersion and longer residence time. The effect of molecular weight of polystyrene on clay dispersion and property enhancement was evaluated. Nanocomposite structure was characterized by wide angle x-ray diffraction (WAXD) and transmission electron microscopy (TEM). Thermal stability and mechanical and barrier properties were also determined. The quality of dispersion of organically modified montmorillonite depended on the molecular weight of the polystyrene resin. Barrier properties were measured and compared to predictions of permeability models available in the literature. Clay dispersion and property enhancement were explained in relation to the surface characteristics of the organoclays, and the work of adhesion at the polystyrene-clay interface was correlated with the tensile modulus of the nanocomposites. DOI : 10.3139/217.2103 En ligne : https://drive.google.com/file/d/11d_scF94azCK10c5LMJ8YaRnjn5wYBa8/view?usp=drive [...] Format de la ressource électronique : Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2669
in INTERNATIONAL POLYMER PROCESSING > Vol. XXIII, N° 1 (03/2008) . - p. 119-128[article]Réservation
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Code-barres Cote Support Localisation Section Disponibilité 009860 - Périodique Bibliothèque principale Documentaires Disponible
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| Code-barres | Cote | Support | Localisation | Section | Disponibilité |
|---|---|---|---|---|---|
| 009860 | - | Périodique | Bibliothèque principale | Documentaires | Disponible |
