Comparison of fibre reorientation of short-and long-fibre reinforced polypropylene by injection molding with a rotating mold core / Philipp Land in INTERNATIONAL POLYMER PROCESSING, Vol. 38, N° 1 (2023)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 38, N° 1 (2023) . - p. 97-110 Titre : Comparison of fibre reorientation of short-and long-fibre reinforced polypropylene by injection molding with a rotating mold core Type de document : texte imprimé Auteurs : Philipp Land, Auteur ; Thorsten Krumpholz, Auteur ; Hans-Peter Heim, Auteur Année de publication : 2023 Article en page(s) : p. 97-110 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres -- Moulage par micro-injection Composites à fibres courtes Composites à fibres de verre -- Propriétés mécaniques Composites à fibres longues Distribution et orientation des fibres Moules à noyau rotatif Polypropylène Index. décimale : 668.4 Plastiques, vinyles Résumé : With a rotating mold core during the injection molding of fibre-reinforced plastics, the rotational shear caused by the rotation is superimposed on the injection-induced shear. This allows the fibre orientation in this area to be intentionally manipulated so that, for example, in the case of internal pressure loading, the fibres can be oriented in the tangential main loading direction. This paper deals with the impact of a rotating mold core on the fibre orientation and burst strength of short-and long-fibre-reinforced polypropylene. It is shown that the fibre orientation and strength can be significantly influenced for both short and long fibres, whereby increases in bursting strength of mostly over 80%, in some cases over 200%, could be achieved. The ultimate strength depends, among other things, on the wall thickness used and the fibre content. Major differences between the short-and long-fibre-reinforced polypropylene are less evident in the strength and more in the fibre orientation. Note de contenu : - MATERIALS AND METHODS : Process implementation and manufacturing of test specimens - Materials - Burst pressure test - Fibre orientation analysis - RESULTS : Short-fibre reinforced PP - Long-fibre reinforced PP - Failure behavior DOI : https://doi.org/10.1515/ipp-2022-4252 En ligne : https://drive.google.com/file/d/13BYnremJZznNj0YGHJRLOJNM_8ThgSK1/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39198 [article]

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Effect of mixing conditions and polymer particle size on the properties of polypropylene/graphite nanoplatelets micromoldings / Renze Jiang in INTERNATIONAL POLYMER PROCESSING, Vol. 37, N° 4 (2022)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 37, N° 4 (2022) . - p. 372-382 Titre : Effect of mixing conditions and polymer particle size on the properties of polypropylene/graphite nanoplatelets micromoldings Type de document : texte imprimé Auteurs : Renze Jiang, Auteur ; Piyush Lashkari, Auteur ; Shengtai Zhou, Auteur ; Andrew N. Hrymak, Auteur Année de publication : 2022 Article en page(s) : p. 372-382 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Caractérisation Composites à fibres -- Moulage par micro-injection Composites à fibres de graphite Conducteurs organiques Microstructures Nanoparticules Polypropylène Thermocinétique Index. décimale : 668.4 Plastiques, vinyles Résumé : In this study, properties of polypropylene/graphite nanoplatelets (PP/GNP) composites and corresponding micromoldings were systematically studied in terms of filler loading concentrations and mixing methods. PP of different forms, i.e., PP pellets and powders, were adopted to fabricate PP/GNP composites. Additionally, a comparative study of precoating GNP and PP powders using solvent-based solution blending and ultrasonication-assisted mixing was performed. Results showed that PP/GNP composites prepared using powder form PP resulted in at least one order of magnitude higher electrical conductivity than using pellet form PP and further reduced the percolation threshold from 12.5 to 10 wt%, which was related to the state of filler distribution within corresponding moldings. Morphology observations revealed that microparts prepared with powder-PP/GNP composites exhibited less preferential alignment of GNP particles along the flow direction when compared with those molded using pellet-PP/GNP counterparts, which was helpful in improving the overall electrical conductivity for PP/GNP micromoldings. Note de contenu : - EXPERIMENTAL SECTION : Materials - Sample preparation - CHARACTERIZATION : Electrical conductivity - Morphology - Differential scanning calorimetry - RESULTS AND DISCUSSION : Electrical conductivity - Morphology - Differential scanning calorimetry - Table 1 : Characteristic Data from DSC Scans for PP/GNP feeds (top row) and µIM microparts (bottom row). Cycle 1: 1st heating cycle. Cycle 2: cooling cycle. Cycle 3: 2nd heating cycle DOI : https://doi.org/10.1515/ipp-2022-0004 En ligne : https://drive.google.com/file/d/1qw8Ibyf-E7sqUi1vjl_V9cgnu7o1L3jN/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37913 [article]

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Electrical, morphological and thermal properties of microinjection molded polypropylene/multi-walled carbon nanotubes nanocomposites / S.-T. Zhou in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIII, N° 4 (08/2018)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIII, N° 4 (08/2018) . - p. 514-524 Titre : Electrical, morphological and thermal properties of microinjection molded polypropylene/multi-walled carbon nanotubes nanocomposites Type de document : texte imprimé Auteurs : S.-T. Zhou, Auteur ; Andrew N. Hrymak, Auteur ; Musa R. Kamal Année de publication : 2018 Article en page(s) : p. 514-524 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres -- Moulage par micro-injection Composites à fibres de carbone Composites à fibres de carbone -- Propriétés électriques Composites à fibres de carbone -- Propriétés thermiques Mélanges-maîtres (chimie) Nanotubes de carbone à parois multiples Un nanotube de carbone multifeuillet est constitué de plusieurs feuillets de graphènes enroulés les uns autour des autres. Il existe deux modèles pour décrire la structure des nanotubes multifeuillets : - le modèle poupée russe: les plans de graphène sont arrangés en cylindres concentriques ; - le modèle parchemin: un seul feuillet de graphène est enroulé sur lui-même, comme une feuille de papier. Polypropylène Index. décimale : 668.4 Plastiques, vinyles Résumé : A series of polypropylene/multi-walled carbon nanotubes (PP/CNT) nanocomposites were prepared by masterbatch dilution, then followed by microinjection molding under a defined set of processing conditions. A micropart (μ-part) which has a three-step decrease in thickness along the flow direction was fabricated to study the effect of abrupt geometrical changes in mold cavities on the distribution of CNT in PP. To facilitate characterization, the μ-parts were divided into three sections based on thickness. The distribution of CNT within each section of subsequent μ-parts was evaluated by morphological observations and electrical resistivity measurements. In addition, the thermal properties of pure PP and PP/CNT nanocomposites as well as each section of subsequent μ-parts, were assessed by differential scanning calorimetry and thermogravimetric analysis. Note de contenu : - EXPERIMENTAL SECTION : Materials - Preparation of microparts - Characterization - RESULTS AND DISCUSSION : DC electrical resistivity and dielectric measurements - Morphology - Differential scanning calorimetry - Thermogravimetric analysis DOI : 10.3139/217.3541 En ligne : https://drive.google.com/file/d/1D1_reEOphAhQ8gOARPxFYLxIFILFle_z/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=30891 [article]

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Micro-injection molding of polymer nanocomposites composition-process-properties relationship in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 3 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 3 (2021) Titre : Micro-injection molding of polymer nanocomposites composition-process-properties relationship Type de document : texte imprimé Année de publication : 2021 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Caractérisation Composites à fibres -- Moulage par micro-injection Composites à fibres de carbone -- Propriétés électriques Composites à fibres de carbone -- Propriétés mécaniques Composites à fibres de carbone -- Propriétés thermiques Matériaux hybrides Microstructures Plan d'expérience Polyamide 66 Polycarbonates Rhéologie Index. décimale : 668.4 Plastiques, vinyles Résumé : The mechanical, electrical, thermal, and rheological properties of micro injection molded nanocomposites comprising 2% and 5% carbon nanotubes (CNTs) incorporated in polycarbonate (PC), and polyamide 66 (PA) were studied. The design of experiments method was used to investigate the composition-process – properties relationship. Results indicated that the process variables significantly affected the flow patterns and resulting morphology during the filling stage of the microinjection molding (lIM) process, using 0.45 mm diameter lIM samples. Two distinct flow regimes have been identified in lIM using the low cross-section samples. The first was a conventional “fountain flow,” which resulted in a skin/core structure and reduced volume resistivity up to 10 X cm in the case of 5% CNTs and up to 100 X cm in 2% CNTs, in both polymers, respectively. In addition, inferior mechanical properties were obtained, attributed to polymer degradation under high shear rate conditions, when practicing high injection speeds, high mold temperatures, and high screw rotation velocities. The second was a “plug flow” due to wall slippage, obtained under low injection speeds, low mold temperatures, and low rotation velocities, leading to a substantial increase in modulus of elasticity (60%) with increased electrical resistivity up to 103 X cm for 5% CNTs and 105 X cm for 2% CNTs, respectively. The rheological percolation threshold was obtained at 2% CNTs while the electrical threshold was attained at 0.4% CNTs, in both polymers. It was concluded that in lIM, the process conditions should be closely monitored. In the case of high viscous heating, degradation of mechanical properties was obtained, while skin- core morphology formation enhanced electrical conductivity. Note de contenu : - EXPERIMENTAL : Materials - Preparation of microparts - Characterization - RESULTS AND DISCUSSION : Rheological properties - Flow analysis - Design of experiments - Electrical properties - Microstructure - Table 1 : Micro molding vs. conventional molding - Table 2 : DOE scheme - Table 3 : The main parameters with the highest significance on mechanical properties of μIM DOI : https://doi.org/10.1515/ipp-2020-4065 En ligne : https://drive.google.com/file/d/1wsZNRlMh8sy7_TbAxv4oovCgnP2Mipp9/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36370 [article]

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Tensile, rheological and morphological characterizations of multi-walled carbon nanotube/polypropylene composites prepared by microinjection and compression molding / Gulstan S. Ezat in INTERNATIONAL POLYMER PROCESSING, Vol. 37, N° 1 (2022)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 37, N° 1 (2022) . - p. 45-53 Titre : Tensile, rheological and morphological characterizations of multi-walled carbon nanotube/polypropylene composites prepared by microinjection and compression molding Type de document : texte imprimé Auteurs : Gulstan S. Ezat, Auteur ; Adrian L. Kelly, Auteur ; Mansour Youseffi, Auteur ; Phil D. Coates, Auteur Année de publication : 2022 Article en page(s) : p. 45-53 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres -- Moulage par compression Composites à fibres -- Moulage par micro-injection Composites à fibres de carbone Composites à fibres de carbone -- Propriétés mécaniques Dispersions et suspensions Matériaux hybrides Morphologie (matériaux) Nanotubes de carbone à parois multiples Un nanotube de carbone multifeuillet est constitué de plusieurs feuillets de graphènes enroulés les uns autour des autres. Il existe deux modèles pour décrire la structure des nanotubes multifeuillets : - le modèle poupée russe: les plans de graphène sont arrangés en cylindres concentriques ; - le modèle parchemin: un seul feuillet de graphène est enroulé sur lui-même, comme une feuille de papier. Rhéologie Traction (mécanique) Index. décimale : 668.4 Plastiques, vinyles Résumé : Polypropylene (PP) reinforced with 2 and 4 wt% of multi-walled carbon nanotubes (MWNT) were melt-blended in twin screw extruder and then molded by compression or micromolding process. The impact of injection speed on the surface morphology, rheological and tensile characteristics was investigated by using a scanning electron microscope, parallel plate rheometry, and tensiometry. Results showed that the tensile properties of micro-molded specimens were remarkably higher than those of the compression molded sheets. Compared to compression molded sheets, micromolded specimens demonstrated up to 40 and 244% higher tensile stiffness and yield strength, respectively, most likely due to the alignment of polymer chain segments in the flow direction induced during the micromolding process. It was observed that the fast filling speed caused a drop in the tensile properties of the nanocomposites and polymer. Rheological examination revealed that the presence of a rheological percolation network in the nanocomposites produced by micromolding and the fast injection speed was beneficial for establishing the percolated network. Morphological examination revealed that the size of nanotube agglomerations that appeared in micromolded specimens was up to five times smaller than in compression molded sheets and the agglomeration size decreased with the increase of the injection speed. Note de contenu : - EXPERIMENTAL : Materials - Nanocomposite preparation and molding - Measurement of tensile characteristics - Rheological analysis - Morphological characterization - RESULTS AND DISCUSSION : Tensile properties - Rheological analyzes - Dispersion of MWNT DOI : https://doi.org/10.1515/ipp-2021-4156 En ligne : https://drive.google.com/file/d/1E0uzUvti86xTq18f8Ez7VPoGMZsI9rij/view?usp=share [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=38440 [article]

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The filling behavior of reinforcing glass fiber in micro injection molding / G. L. Liou in INTERNATIONAL POLYMER PROCESSING, Vol. XXV, N° 4 (09/2010)  

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