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Flow-fiber coupled viscosity in injection molding simulations of short fiber reinforced thermoplastics / Tianyi Li in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 158-171 Titre : Flow-fiber coupled viscosity in injection molding simulations of short fiber reinforced thermoplastics Type de document : texte imprimé Auteurs : Tianyi Li, Auteur ; J. F. Luyé, Auteur Année de publication : 2019 Article en page(s) : p. 158-171 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres courtes Distribution et orientation des fibres Rhéologie Simulation par ordinateur Viscosité Index. décimale : 668.4 Plastiques, vinyles Résumé : The main objective of this paper is to numerically investigate the use of fiber-dependent viscosity models in injection molding simulations of short fiber reinforced thermoplastics with latest commercial software. We propose to use the homogenization-based anisotropic rheological model to take into account flow-fiber coupling effects. The 4th-order viscosity tensor is approximated by an optimal scalar model and then implemented in the Moldflow Insight API framework. Numerical simulations are performed for a test-case rectangular plate with three fiber orientation models. The resulting coupled flow kinematics and fiber evolutions are then compared to the standard uncoupled simulations. Interpretations are given based on detailed post-processing of the field results. Certain deformation conditions are expected to be better taken into account, which may also in return lead to an improved fiber orientation prediction. Preliminary confrontation between flow-fiber coupled simulations and existing experimental data is then presented at the end of the paper. Note de contenu : - FLOW-FIBER COUPLED VISCOSITY MODELS : Anisotropic fiber-induced rheological equations - Optimal scalar approximation of the 4th-order viscosity tensor - Implementation in the moldflow insight API framework - TEST-CASE SIMULATIONS ON A RECTAGULAR PLATE : Fiber orientations predicted by uncoupled simulation - Coupled simulations using the folgar-tucker model - Coupled simulations using the MRD model - Coupled simulations with the RSC model - PRELIMINARY CONFRONTATION WITH EXPERIMENTAL DATA - CONCLUSIONS AND FUTURE WORK DOI : 10.3139/217.3706 En ligne : https://www.degruyter.com/document/doi/10.3139/217.3706/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32392 [article]

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Effects of cooling ways on the structure of polypropylene hollow fiber membranes prepared by stretching / D.-J. Luo in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 172-181 Titre : Effects of cooling ways on the structure of polypropylene hollow fiber membranes prepared by stretching Type de document : texte imprimé Auteurs : D.-J. Luo, Auteur ; F.-J. Wei, Auteur ; H.-J. Shao, Auteur ; K.-Z. Zhang, Auteur ; Z.-Y. Cui, Auteur ; J. Yu, Auteur ; S.-H. Qin, Auteur Année de publication : 2019 Article en page(s) : p. 172-181 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Essais dynamiques Extrusion filage Fibres creuses Membranes (technologie) Morphologie (matériaux) Polypropylène Porosité Surfaces (Physique) Systèmes de refroidissement Traction (mécanique) Index. décimale : 668.4 Plastiques, vinyles Résumé : Air, water, and DINCH (Di-isononyl-cyclohexane-1,2-dicarboxylate) were selected as the cooling media to prepare polypropylene hollow fiber membranes by melt spinning. The effects of various cooling ways with different cooling rates on the row-nucleated lamellar crystallization were investigated. The crystallinity, orientation and arrangement of the crystals were examined by differential scanning calorimetry (DSC), wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS). Membrane morphology was observed by SEM. The less uniform pores, a layer of amorphous phase, and only a small part of slit-shaped pores were observed on the surface of samples when water and DINCH were used as the heat transfer medium because the fast cooling rate froze the surface molecules and decreased the crystallinity and orientation. However, when air was used as the cooling medium, the higher crystallinity and the better orientation of the annealed hollow fibers were obtained mainly due to the slow cooling rate. Corresponding hollow fiber membranes prepared by stretching had better interconnectivity of pores and larger pure water flux. Thus this study explains why air was selected as the cooling medium to prepare polypropylene hollow fiber membranes which can have larger pure water flux. Also, it provides new insights into the structure control of polypropylene hollow fiber membranes by stretching in order to prepare membranes with high strength. Note de contenu : - EXPERIMENTAL : Materials - Membrane preparation - Differential Scanning Calorimetry - Surface morphology - Tensile properties - Elastic recovery rate - RESULTS AND DISCUSSION : Crystallization and DSC analysis - SAXS and WAXD analysis - Tensile properties and elastic recovery rate - Surfaces morphologies - Porosity and pure water flux DOI : 10.3139/217.3638 En ligne : https://drive.google.com/file/d/1T1rC3UNtaRnspchVpMtyqp5EaKrJkRWH/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32393 [article]

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Fill factor effects in highly-viscous non-isothermal rubber mixing simulations / I. Ahmed in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 182-194 Titre : Fill factor effects in highly-viscous non-isothermal rubber mixing simulations Type de document : texte imprimé Auteurs : I. Ahmed, Auteur ; H. Poudyal, Auteur ; Abhilash J. Chandy, Auteur Année de publication : 2019 Article en page(s) : p. 182-194 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Alliages polymères Caoutchouc Caoutchouc -- Propriétés physiques Caoutchouc -- Propriétés thermiques Fluides non newtoniens Modèles numériques Simulation par ordinateur Index. décimale : 668.4 Plastiques, vinyles Résumé : A finite volume technique in a commercial computational fluid dynamics (CFD) code is employed in this study to simulate transient, incompressible, non-Newtonian and non-isothermal rubber mixing. The simulation processes are conducted in a two-dimensional(2D) domain, where a mixing chamber partially-filled with rubber is equipped with a pair of two-wing non-intermeshing counter-rotating rotors. The main objective is to assess the effect of different fill factors of rubber on dispersive and distributive mixing characteristics by simulating 15 revolutions of the rotors rotating at 20 min−1. 50%, 60%, 70%, 75%, 80% and 90% are the six different fill factors chosen for the study. An Eulerian multiphase method has been applied to solve for the two different phases, rubber and air. The non-Newtonian property of rubber is handled using the shear rate dependent Carreau-Yasuda model, along with an Arrhenius function to include the temperature dependency. In addition to the governing equations related to the conservation of mass, momentum and energy, the volume of fluid (VOF) method is chosen to track the interface between air and rubber. With regard to the results, flow patterns, thermal distributions, viscosity behavior and volume fraction are analyzed for the different fill factors. In addition, dispersive and distributive mixing behavior is also assessed in detail using Lagrangian statistics, such as mixing index, cumulative distribution of maximum shear stress, cluster distribution index (CDI), scale of segregation (SOS) and length of stretch (LOS), calculated from massless particles. Both the Eulerian and Lagrangian results showed that fill factors between 70% and 80% presented the most reasonable and efficient mixing scenario, and also exhibited the best dispersive and distributive mixing characteristics combined. Note de contenu : - Geometry and materials - Governing equations - Computational model - Results and discussion : Thermal distribution - Flow pattern - Rubber volume fraction - Dispersive mixing - Distributive mixing DOI : 10.3139/217.3694 En ligne : https://www.degruyter.com/document/doi/10.3139/217.3694/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32394 [article]

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Morphology and isothermal crystallization kinetics of polypropylene/poly(ethylene-co-vinyl alcohol) blends / D.-J. Luo in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 195-208 Titre : Morphology and isothermal crystallization kinetics of polypropylene/poly(ethylene-co-vinyl alcohol) blends Type de document : texte imprimé Auteurs : D.-J. Luo, Auteur ; H.-J. Shao, Auteur ; F.-J. Wei, Auteur ; K.-Z. Zhang, Auteur ; Z.-Y. Cui, Auteur ; J. Yu, Auteur ; S.-H. Qin, Auteur Année de publication : 2019 Article en page(s) : p. 195-208 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Alliages polymères Caoutchouc Copolymère éthylène alcool de vinyle C'est aujourd'hui le matériau le plus utilisé dans l'emballage rigide alimentaire. Il peut être utilisé avec des matériaux de structure comme le polyéthylène, polypropylène ou polystyrène. Ce copolymère présente une excellente imperméabilité à l'oxygène, au gaz carbonique et aux arômes, à condition de protéger de l'influence de l'humidité qui fait chuter fortement ses performances. Pour palier cet inconvénient, il est souvent pris en sandwich dans des structures multicouches à base de polyoléfines PE ou PP peu sensibles à l'humidité. Il est utilisé pour les emballages de compotes, jus de fruits, fromages, sauces, crèmes et yaourts, mayonnaise, sauce tomate... Cristallisation Diffractométrie de rayons X Polypropylène Index. décimale : 668.4 Plastiques, vinyles Résumé : Polypropylene (PP)/poly(ethylene-co-vinyl alcohol) (EVOH) blends were prepared by melt blending using PP-g-MAH as a compatabilizer. The microstructure and rheological behavior of PP/EVOH blends were studied. The results showed the that EVOH particles were uniformly dispersed in the PP matrix and inhibited the mobility of PP chains. The isothermal crystallization kinetics and morphology development of PP/EVOH blends were compared with that of pure PP. It was found that the EVOH essentially acted as an effective nucleating agent for PP, which could significantly increase the nucleation rate because the EVOH molecules in PP/EVOH blends aggregated together to form interface. Therefore, the introduction of EVOH increased the overall rate of isothermal crystallization compared with pure PP, although the PP molecular chains would be hindered seriously if excessive amounts of EVOH were added. X-ray diffraction showed that pure PP and PP/EVOH blends exhibited an identical crystal structure, and the crystallinity of the PP phase in the blends was not significantly different from that of pure PP. Note de contenu : - EXPERIMENTAL : Materials - Sample preparation - Characterization - RESULTS AND DISCUSSION : Microstructural and viscoelastic properties of PP/EVOH blends - Non-isothermal crystallization behavior of PP/EVOH blends - Isothermal crystallization kinetics of PP/EVOH blends - Melting behavior of isothermally crystallized PP/EVOH blends - Morphology and microstructure of PP/EVOH blends DOI : 10.3139/217.3589 En ligne : https://www.degruyter.com/document/doi/10.3139/217.3589/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32395 [article]

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Mechanical and thermal properties of teak wood flour/starch filled high density polyethylene composites / Kishor Biswas in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 209-218 Titre : Mechanical and thermal properties of teak wood flour/starch filled high density polyethylene composites Type de document : texte imprimé Auteurs : Kishor Biswas, Auteur ; V. Khandelwal, Auteur ; S. N. Maiti, Auteur Année de publication : 2019 Article en page(s) : p. 209-218 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Adhésion Amidons Analyse mécanique dynamique Analyse thermique Bois Charges (matériaux) Composites -- Extrusion Composites -- Propriétés mécaniques Composites -- Propriétés thermiques Farines végétales Fourier, Spectroscopie infrarouge à transformée de Morphologie (matériaux) Polyéthylène greffé anhydride maléique Polyéthylène haute densité Thermogravimétrie Index. décimale : 668.4 Plastiques, vinyles Résumé : Teak wood flour (TWF) reinforced HDPE composites were prepared and characterized in terms of mechanical, morphological and thermal properties using 2% polyethylene grafted with maleic anhydride (PE-g-MAH) as compatibilizer. The composites were prepared by twin screw extrusion and samples were prepared by injection molding. Mechanical properties increased with the incorporation of TWF, Starch and PE-g-MAH. Tensile strength and Young's modulus increased by 96% and 207%, respectively for TWF (40%)-HDPE composite as compared to virgin matrix. Scanning electron microscopy revealed good interface between TWF and matrix. FT-IR spectra confirmed the esterification reaction and H-bond between anhydride group of PE-g-MAH and cellulose of TWF. The DSC results showed that the melting temperature increased from 129°C to 137°C while crystallization (%) decreased from 40.49% for HDPE to 34.77% for 40% TWF composites, respectively. The storage modulus increased for all the composites at low temperature. Glass transition temperature practically remained unaffected by filler loading. Note de contenu : - MATERIALS - COMPOSITE PREPARATION AND SAMPLE PREPARATION -TESTING AND CHARACTERIZATION : Tensile and flexural properties - Morphology - Fourier Transform Infrared Spectroscopy (FTIR) - Thermal Gravimetric Analysis (TGA) and Differential Scanning Calorimetry (DSC) - Dynamic Mechanical Analysis (DMA) - RESULTS AND DISCUSSION : Tensile and flexural properties - Interfacial adhesion - Thermal analysis - Dynamic mechanical analysis DOI : 10.3139/217.3640 En ligne : https://drive.google.com/file/d/1HFd2YX3CeXYRhUOr8N73v0WAhNmLksR2/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32396 [article]

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Edge effect in hot embossing and its influence on global pattern replication of polymer-based microneedles / J. Zhuang in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 231-238 Titre : Edge effect in hot embossing and its influence on global pattern replication of polymer-based microneedles Type de document : texte imprimé Auteurs : J. Zhuang, Auteur ; D.-M. Wu, Auteur ; H. Xu, Auteur ; Y. Huang, Auteur ; Y. Liu, Auteur ; J.-Y. Sun, Auteur Année de publication : 2019 Article en page(s) : p. 231-238 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Effet de bord Gaufrage à chaud Micro-aiguilles Polyméthacrylate de méthyle Le 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 : 668.4 Plastiques, vinyles Résumé : Hot embossing was used to fabricate a microneedle array on poly(methyl methacrylate) (PMMA) substrates. Both experimental and numerical researches were carried out to investigate the whole formation process. The results showed that the edge effect would significantly influence the replication rate of final products. An optimization design of convex flow barrier was proposed to improve the replication efficiency and structure uniformity. Furthermore, optimum parameters of the flow barrier were found to be 2 mm in length and 0.2 mm in height. Reasonable high molding temperature and force were conducive to reduce the filling time and increase the average height of microneedles. Note de contenu : - NUMERICAL SIMULATION : Physical and numerical modeling - Material properties - EXPERIMENTAL : Material and equipment - Experimental design - RESULTS AND DISCUSSION : Edge effect and optimization of structure uniformity - Influence of molding temperature and embossing force on mold filling in hot embossing process - Comparison of the average height of microneedles under different parameters based on the numerical and experimental results DOI : 10.3139/217.3726 En ligne : https://drive.google.com/file/d/1wyGC0z4P0QBNlnd5ayxq5ff6xuAhl9uZ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32397 [article]

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Enhancing flame retardancy, thermal stability, physical and mechanical properties of polyethylene foam with polyphosphate modified expandable graphite and ammonium polyphosphate / M.-F. Ma in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 239-247 Titre : Enhancing flame retardancy, thermal stability, physical and mechanical properties of polyethylene foam with polyphosphate modified expandable graphite and ammonium polyphosphate Type de document : texte imprimé Auteurs : M.-F. Ma, Auteur ; Xiaoyan Pang, Auteur ; R. Chang, Auteur Année de publication : 2019 Article en page(s) : p. 239-247 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Graphite Ignifugeants Composé chimique utilisé pour réduire l'inflammabilité. Il peut être incorporé au produit durant sa fabrication ou appliqué ultérieurement à sa surface. Mousses plastiques Mousses plastiques -- Propriétés mécaniques Mousses plastiques -- Propriétés physiques Mousses plastiques -- Propriétés thermiques Polyéthylène basse densité linéaire Polyphosphate d'ammonium Polyphosphate Un polyphosphate est un sel ou un ester d'oxyanions polymères formés à partir d'unités structurales tétraédriques PO 4 (phosphate) liées entre elles par le partage d'atomes d'oxygène. Les polyphosphates peuvent adopter des structures cycliques linéaires ou cycliques. En biologie, les esters polyphosphates ADP et ATP sont impliqués dans le stockage de l'énergie. Une variété de polyphosphates trouvent une application dans la séquestration des minéraux dans les eaux municipales, étant généralement présents à 1 à 5 ppm. GTP, CTP et UTP sont également des nucléotides importants dans la synthèse des protéines, la synthèse des lipides et le métabolisme des glucides, respectivement. Les polyphosphates sont également utilisés comme additifs alimentaires, marqués E452. (Wikipedia) Index. décimale : 668.4 Plastiques, vinyles Résumé : The method of preparing polyolefin foam with good flame retardancy, thermal stability, and physical and mechanical properties was investigated. Foaming condition of linear low density polyethylene (LLDPE) was investigated with triphenyl phosphate (TPP) as plasticizer, NaHCO3 as foaming agent. The influence of modified expandable graphite (EGP) and ammonium polyphosphate (II) on foam density, compression strength, combustion characteristics and thermal stability was explored. Results verified that EGP presented better dilatability and flame retardancy than the normal expandable graphite. Addition of EGp improved the limiting oxygen index (LOI) of 15NaHCO3/100 LLDPETPP/30EGp foam from 18.8% to 24.6%. Furthermore, the combination of EGp and ammonium polyphosphate (II) (APP) at the mass ratio of 2:1 improved the LOI of 15NaHCO3/100 LLDPETPP/20EGp/10APP sample to 27.9%, and the vertical burning UL-94 level reached V-0, indicating that this material was flame retardant. Although these additives made 15NaHCO3/100 LLDPETPP/20EGp/10APP composite exhibit a high density of 142.5 kg m−3, which was increased by 12.3 wt% relative to the 15NaHCO3/100 LLDPETPP foam, it could improve the compressive strength to 0.4747 MPa, which was about 2.7 times that of the matrix. The thermal stability of the material was also enhanced. Note de contenu : - EXPERIMENTAL PROCEDURE : Raw materials - Sample preparation - Measurement and characterization of different properties - RESULTS AND DISCUSSION : TG/DTG analysis of the prepared GICs - Influence of FRs on physical and mechanical properties of LLDPE foam - Influence of FRs on LLDPE foams combustion properties - Combustion residue morphology - Influence of FRs on LLDPE foams thermal stability - Possible flame retardant mechanism DOI : 10.3139/217.3714 En ligne : https://drive.google.com/file/d/1Bmrx4Qqz6pEqk72LCifUoz3HT62hiej1/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32398 [article]

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Processing LDS-circuit boards by selective laser sintering / Andreas Wörz in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 248-254 Titre : Processing LDS-circuit boards by selective laser sintering Type de document : texte imprimé Auteurs : Andreas Wörz, Auteur ; K. Wudy, Auteur ; Dietmar Drummer , Auteur ; Markus Heidebrecht, Auteur ; S. Klein, Auteur Année de publication : 2019 Article en page(s) : p. 248-254 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Electronique imprimée Frittage laser Matières plastiques -- Additifs Matières plastiques -- Métallisation Matières plastiques -- Propriétés mécaniques Matières plastiques -- Propriétés thermiques Polyamide 12 Index. décimale : 668.4 Plastiques, vinyles Résumé : As the demand for individualized products rises, the development and need for additive manufacturing (AM) techniques such as selective laser sintering (SLS) has strongly increased. The industrial use of these procedures for prototypes or small-scale production lines has grown due to their specific characteristics like the high achievable complexity. With the increasing demand for electrification and functionalization, the combination of AM with laser-direct structuring (LDS) gains interest. Therefore, the powder used for the investigation is dry coated with a LDS-additive, which enables laser activation and a metallization of the activated sections in a metallization bath. To characterize the influence of the LDS-additive on the process, the powder properties were investigated for unfilled and successive increased additive content. The thermal process window was identified by standard and process adapted isothermal differential scanning calorimetry. This showed a decrease of the isothermal crystallization time due to nucleation effects of the additive. Subsequently, parts were produced with a parameter study and showed a demand for a higher energy density. The resulting parts were then metallized with a parameter variation and characterized by stereomicroscopy. To investigate the influence of the different parameter sets and the LDS content, the mechanical properties were determined. Note de contenu : - Material - Bulk properties - Flowability - Thermal properties - Processing - Metallization - Mechanical characterization DOI : 10.3139/217.3670 En ligne : https://drive.google.com/file/d/1XGo-V469wWoo_DDCz8B8wH-dRuVynXSW/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32399 [article]

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Structural and optical characteristics of laser irradiated CdSe/PVA nanocomposites in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 255-261 Titre : Structural and optical characteristics of laser irradiated CdSe/PVA nanocomposites Type de document : texte imprimé Année de publication : 2019 Article en page(s) : p. 255-261 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Films plastiques -- Propriétés optiques Irradiation lasers Nanoparticules Polyacétate de vinyle Séléniure de cadmium Le séléniure de cadmium (CdSe) est un composé du sélénium et du cadmium. Toxicité : Le cadmium est un métal lourd toxique et des précautions appropriées doivent être prises lors de sa manipulation et celle de ses composés. Les séléniures sont toxiques en grande quantité. Le séléniure de cadmium est une substance cancérogène connue pour les humains et l'attention médicale doit être recherchée en cas d'ingestion ou si le contact avec la peau ou les yeux se produit. Applications : Le CdSe est transparent aux radiations infrarouges et est parfois utilisé dans la photorésistance et dans les fenêtres pour les instruments utilisant la lumière infrarouge. Le matériau est également hautement luminescent. Ce semi-conducteur est un redresseur de courant. Il sert dans les cellules photoélectriques, mais aussi sur les écrans TV, les écrans fluorescents et les posemètres. Index. décimale : 668.4 Plastiques, vinyles Résumé : Nanocomposites of polyvinyl alcohol (PVA) and Cadmium selenide (CdSe) were fabricated by ex-situ casting technique. CdSe nanoparticles were prepared by thermolysis under the flow of nitrogen. Rietveld refinement of x-ray data showed that the prepared CdSe adapts cubic zinc blend structure with a lattice parameter 6.057 Å and a mean grain size of 2 nm. Samples from CdSe/PVA nanocomposite have been exposed to infrared (IR) laser fluences in the range 0–19.6 J/cm2. The effect of IR laser radiation on the structural and optical properties of CdSe/PVA has been investigated using XRD and UV-vis spectroscopy. UV/VIS absorption spectra confirm the formation of hybridized film CdSe/PVA nanocomposite with refractive index in the range of 1.4119–1.8621 (at 700 nm). Also, the laser radiation reduces the optical energy gap from 4.1 to 3.43 eV which could be attributed to the increase in structural disorder of the irradiated CdSe/PVA nanocomposites due to the formation of coordination reaction between OH of PVA and CdSe nanoparticles. This means that the laser radiation led to a more compact structure of CdSe/PVA nanocomposite and causes proper dispersion of CdSe nanoparticles in the PVA matrix. Further, the Commission Internationale de E'Claire (CIE units x, y and z) methodology was applied in this work for the description of colored samples. The color intensity ΔE, which is the color difference between the non irradiated sample and the irradiated ones, was increased from 11.40 to 30.57 with increasing the laser fluence up to 19.6 J/cm2. Note de contenu : - MATERIALS AND METHODS : Preparation of CdSe nanoparticles and CdSe/PAV nanocomposite films - Irradiation facilities - Measurements and instrumentations - RESULTS AND DISCUSSION : Structure and microstructure analysis - Optical performance of CdSe at PVA nanocomposites - Color difference analysis of CdSe at PVA nanocomposites DOI : 10.3139/217.3729 En ligne : https://drive.google.com/file/d/1ViWmYU20MU2B8aimde2NQYL-ZMBmFPVz/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32400 [article]

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The effect of ultraviolet ageing on the flame retardancy, thermal stability and mechanical properties of LGFPP/IFR / W.-D. He in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 262-269 Titre : The effect of ultraviolet ageing on the flame retardancy, thermal stability and mechanical properties of LGFPP/IFR Type de document : texte imprimé Auteurs : W.-D. He, Auteur ; Y. Zhou, Auteur ; Y.-F. Wu, Auteur ; J.-B. Guo, Auteur ; X.-L. Chen, Auteur ; X. Zhang, Auteur Année de publication : 2019 Article en page(s) : p. 262-269 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres de verre Composites à fibres de verre -- Effets du rayonnement ultraviolet Composites à fibres de verre -- Propriétés mécaniques Ignifugeants Composé chimique utilisé pour réduire l'inflammabilité. Il peut être incorporé au produit durant sa fabrication ou appliqué ultérieurement à sa surface. Intumescence (chimie) Matières plastiques -- Détérioration Polypropylène Stabilité thermique Index. décimale : 668.4 Plastiques, vinyles Résumé : In this work, long glass fibre reinforced polypropylene/intumescent flame retardants (LGFPP/IFR) composites are exposed to ultraviolet (UV) radiation with wavelength of 340 nm for 0–800 h. The effects of UV ageing on the flame retardancy, thermal stability and mechanical properties of LGFPP/IFR composites are investigated and discussed by limiting oxygen index (LOI), UL–94 test, cone calorimeter test (CCT), thermogravimetric analysis (TGA), scanning electronic microscopy (SEM), mechanical properties and energy dispersive X-ray analysis (EDAX). A slight variation in LOI values and UL-94 levels are observed, and CCT results display a lower heat release rate for all aged samples. The TGA result also shows that aged samples have a higher degradation temperature with the prolongation of the aging time. EDAX showed higher content of the O, P and N elements on the surface of samples after 600 h ageing, which means partly gathering of IFR particles. The tensile, bending and impact strengths decrease after ageing, and the fracture morphology shows that interface debonding occurs. Note de contenu : - EXPERIMENTAL : Materials - Preparation of samples - Measurements characterization - RESULTS AND DISCUSSION : UL-94 and LOI - Dynamic combustion - Thermal stability - EDAX results - Mechanical properties and fracture morphology DOI : 10.3139/217.3707 En ligne : https://drive.google.com/file/d/1rlrNh-brKe-1J_BJc7BhLFdHeM-0Qt5n/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32401 [article]

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Three-dimensional, non-isothermal simulations of the effect of speed ratio in partially-filled rubber mixing / H. Poudyal in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 219-230 Titre : Three-dimensional, non-isothermal simulations of the effect of speed ratio in partially-filled rubber mixing Type de document : texte imprimé Auteurs : H. Poudyal, Auteur ; I. Ahmed, Auteur ; Abhilash J. Chandy, Auteur Année de publication : 2019 Article en page(s) : p. 219-230 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Calcul Caoutchouc Ecoulement tridimensionnel Mélanges (chimie) Rhéologie Simulation par ordinateur Index. décimale : 668.4 Plastiques, vinyles Résumé : Three-dimensional, transient, non-isothermal calculations have been carried out using a commercial computational fluid dynamics (CFD) software in a two-wing rotor-equipped chamber partially-filled (75% fill factor) with rubber, to analyze the mixing efficiency for three different rotor speed ratios of 1, 1.125 and 1.5. The moving mesh technique has been used to incorporate the motion of the rotors. The Eulerian based volume of fluid (VOF) method has been used to track the interface between the two fluids, which are rubber and air. To assign the highly viscous and non-Newtonian properties of rubber, the Carreau-Yasuda model along with an exact Arrhenius formulation that accounts for the shear and temperature dependent viscosity, has been used here. Governing equations including the continuity, momentum and energy equations have been solved to characterize the flow field and various mixing parameters. Eulerian-based fields such as velocity magnitude, viscous heat generation, and average temperature and viscosity are compared between cases with different speed ratios. Dispersive and distributive mixing behaviour are assessed through a Lagrangian approach that tracks the paths of a set of massless particles. Statistical quantities such as cumulative distribution of maximum shear stress, cluster distribution index, and axial and inter-chamber particle transfer rates are calculated and presented as well. Results showed that the speed ratio of 1.5 displayed the best dispersive and distributive mixing characteristics in comparison to the other cases. Note de contenu : - Governing equations - Material properties and boundary conditions - Results : Eulerian results : flow and heat transfer - Lagrangian results : dispersive and distributive mixing measures DOI : 10.3139/217.3680 En ligne : https://drive.google.com/file/d/1u9g_UtA4YlEcu6gAGc8FUszdVBTZqS69/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32402 [article]

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Preparation and characterization of a biocomposite based on cork microparticles in poly(B-hydroxybutyrate)-co-poly(B-hydroxyvalerate) matrix / Mariem Ayadi in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 270-278 Titre : Preparation and characterization of a biocomposite based on cork microparticles in poly(B-hydroxybutyrate)-co-poly(B-hydroxyvalerate) matrix Type de document : texte imprimé Auteurs : Mariem Ayadi, Auteur ; R. Ben Cheikh, Auteur ; N. Dencheva, Auteur ; Z. Denchev, Auteur Année de publication : 2019 Article en page(s) : p. 270-278 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Allongement à la rupture Charges (matériaux) Composites -- Moulage par compression Composites -- Propriétés mécaniques Composites -- Propriétés thermiques Copolymères Elasticité Essais dynamiques Liège Matériaux hybrides Particules (matières) Poly-B-hydroxybutyrate poly-B-hydroxyvalérate Traction (mécanique) Index. décimale : 668.4 Plastiques, vinyles Résumé : Poly(β-hydroxybutyrate)-co-poly(β-hydroxyvalerate) (PHBV) loaded with 1 to 10 wt.% of cork microparticles (CM) were manufactured via compression molding technique. CM were isolated by alkali, bleaching and acid hydrolysis treatments. They were then added to the PHBV matrices via solution casting technique. The filler microparticles showed typical diameters of 10 to 55 μm. Mechanical tests in tension showed that in PHBV containing 5 wt.% CM the Young's modulus and the tensile strength increased by 50% and 10% respectively. Meanwhile, the elongation at break decreased by 70% for the same CM content. The mechanical behavior of the reinforced composites was discussed in conjunction with the morphology of the samples studied by optical and electron microscopy. The temperature of initial degradation Tid, the temperature at 5% weight loss Td5% and the temperature of maximum degradation Tdmax increase with increasing CM content by up to 13.6°C, 10.1°C and 12.3°C respectively for the composite of 5 wt.%. The composite with 10 wt.% CM content showed the best thermal stability with temperature increments of 20°C, 14.1°C and 21.5°C respectively. DSC results showed that the presence of CM has a very weak influence on the melting/crystallization behavior of the composites. Note de contenu : - EXPERIMENTAL : Materials - Isolation of cork microparticles - Preparation of the PHBV/CM composites - Characterization - RESULTS AND DISCUSSION : Morphological studies by microscopy - Thermal stability - Melting and crystallization behavior - Mechanical properties DOI : 10.3139/217.3713 En ligne : https://drive.google.com/file/d/11v7IpsHwHZK8xpGqrjvl7LkO-l6rQZjU/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32403 [article]

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Partially filled flow simulation using meshfree method for high viscosity fluid in plastic mixer / Kazuhide Sekiyama in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 2 (05/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 2 (05/2019) . - p. 279-289 Titre : Partially filled flow simulation using meshfree method for high viscosity fluid in plastic mixer Type de document : texte imprimé Auteurs : Kazuhide Sekiyama, Auteur ; S. Yamada, Auteur ; Takaharu Nakagawa, Auteur ; Yasuharu Nakayama, Auteur ; T. Kajiwara, Auteur Année de publication : 2019 Article en page(s) : p. 279-289 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Etat fondu (matériaux) Fluides, Mécanique des Galerkin, Méthode de En mathématiques, dans le domaine de l'analyse numérique, les méthodes de Galerkine sont une classe de méthodes permettant de transformer un problème continu (par exemple une équation différentielle) en un problème discret. Cette approche est attribuée aux ingénieurs russes Ivan Boubnov (1911) et Boris Galerkine (1913). Malaxeurs et mélangeurs Rhéologie Simulation par ordinateur Index. décimale : 668.4 Plastiques, vinyles Résumé : A novel simulation technique for the flow in plastic mixers based on Element-free Galerkin Method (EFGM) has been developed in this study. To improve the simulation accuracy, a “rearrangement” scheme has been employed which eliminates errors caused by the irregular distribution of data points. Through several numerical tests, the new simulation technique has been validated to be applicable to high viscosity fluid flow with enough accuracy. Furthermore, simulation examples for realistic mixers were carried out using the developed technique. From the results, it was found that the developed technique is capable to investigate the relationship between flow behavior inside realistic mixers and operating conditions. Note de contenu : - SIMULATION METHOD : Governing equation - Approximation of velocity field based on MLS interpolation - Discretization - Integration method - Time marching method - New "rearrangement" scheme for improving calculation accuracy - VALIDATION OF DEVELOPED METHOD : Comparison with experiment on rotating cylinder - Comparison with experiment on triangular-shaped rotor - RESULTS AND DISCUSSION OF FLOW SIMULATION INSIDE REALISTIC MIXERS : Numerical simulation condition - Results and discussion DOI : 10.3139/217.3727 En ligne : https://www.degruyter.com/document/doi/10.3139/217.3727/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32404 [article]

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