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The effect of molecular parameters on the thermal behavior of recycled and virgin polyamides and their glass fiber composites / A. Mirzadeh in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 4-12 Titre : The effect of molecular parameters on the thermal behavior of recycled and virgin polyamides and their glass fiber composites Type de document : texte imprimé Auteurs : A. Mirzadeh, Auteur ; H. Ghasemi, Auteur ; Phil J. Bates, Auteur ; Musa R. Kamal, Auteur Année de publication : 2014 Article en page(s) : p. 4-12 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres de verre Composites à fibres de verre -- Recyclage Cristallisation Poids moléculaires Polyamide 6 Polyamide 66 Polymères -- Recyclage Produits et matériaux recyclés Structure moléculaire Index. décimale : 668.4 Plastiques, vinyles Résumé : A study was carried out to evaluate the effects of molecular weight and molecular structure on non-isothermal crystallization behavior of recycled and virgin polyamides (PA) and their corresponding glass fiber (GF) composites. Two different recycled polyamides (PA), namely post-industrial waste (PIW) and post-consumer waste (PCW) were used. The former was obtained from a fiber manufacturer and the latter was recycled from used carpets. The molecular weights of the resins were measured by intrinsic viscosity (IV) measurements and 13carbon nuclear magnetic resonance (13C-NMR). The NMR technique also provided information on PA structure, cis and trans amide conformers content and residual unreacted monomer. Non-isothermal crystallization of the resins was studied using differential scanning calorimetry (DSC). The molecular weights of recycled materials were higher than that of virgin injection molding grade PA-6. However, the crystallization rates (indicated by t1/2) of recycled resins were faster. It could be attributed to the presence of TiO2 in recycled materials. Moreover, the higher cis-amide conformer content of recycled resins suggested higher segmental mobility. On the other hand, the crystallization rate of composites based on recycled PA-6 was slower than that of composites based on the virgin PA-6. The suppression of crystallization rate was apparently due to PA-66 added during the preparation of reinforced recycled resins. This behavior was confirmed by model compounds based on PA-6/PA-66 blends. Note de contenu : - EXPERIMENTAL : Materials - Sample preparation and characterization - RESULTS AND DISCUSSION : Molecular weight measurements - Molecular parameters - Non-isothermal crystallization DOI : 10.3139/217.2775 En ligne : https://drive.google.com/file/d/1KHoV0g1ESFxZQ5ZDVRn6ufTY_hKn1AqA/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20570 [article]

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Carbon nanotube conductive networks through the double percolation concept in polymer systems / A. Abbasi in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 13-27 Titre : Carbon nanotube conductive networks through the double percolation concept in polymer systems Type de document : texte imprimé Auteurs : A. Abbasi, Auteur ; A. Derdouri, Auteur ; Pierre J. Carreau, Auteur Année de publication : 2014 Article en page(s) : p. 13-27 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Butylène téréphtalate cyclique Conduction électrique Matériaux hybrides Matières plastiques -- Moulage par micro-injection 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. Percolation Polybutylène téréphtalate Polypropylène Index. décimale : 668.4 Plastiques, vinyles Résumé : We investigated the electrical conductivity and percolation behavior of binary and ternary nanocomposites based on multiwalled carbon nanotubes (MWCNs) using polypropylene (PP) and a blend of PP with cyclic butylene terephthalate (CBT). The nanocomposites were prepared by diluting a commercial 20 %wtMWCNT PP masterbatch using optimized melt-mixing conditions. The concentration of carbon nanotubes in the diluted PP samples was as low as 0.5 % and as high as 15 % in weight. For the PP/CBT blend CBT concentration was varied up to 40 %wt while the loading of CNT was from 0 to 5 %wt. SEM and TEM techniques were used to examine the quality of the dispersion and the formation of nanotube networks within the polymer matrix. TEM and Raman spectroscopy results showed that for the diluted PP/MWCNT composites the nanotubes are well aligned in samples obtained the microinjection molding process, although the level of alignment is less with crystalline PP than in an amorphous matrix such as polycarbonate (PC). FTIR and XRD results revealed that the orientation of both polymer chains and crystals decreased with the incorporation of nanotubes into PP. The electrical conductivity was also significantly altered by the nanotube alignment in a PP matrix, as was previously observed for PC/MWCNT composites; the conductivity decreased and the percolation threshold rose in highly sheared samples; however, the presence of a crystalline phase improved the conductivity even for high shear conditions through the phenomenon of double percolation threshold. This last concept refers to the requirement that the filler-rich phase be continuous and conductive and not to the existence of two percolation thresholds at two different CNT concentrations. The electrical conductivity of PP/CBT blends was also improved through a double percolation that is the basic requirement for the conductivity of the ternary nanocomposites. Note de contenu : - EXPERIMENTAL : Materials - Nanocomposite preparation and molding - Morphological characterization - Nanotube alignment - Polymer chain and crystal orientation - Rheological measurements - RESULTS : PP nanocomposites - PP/CBT blend nanocomposites DOI : 10.3139/217.2778 En ligne : https://drive.google.com/file/d/1ZJZlKx49qryLnfqR7g8IQdi6ph2N2o-a/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20571 [article]

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Application of the experimental results to the modified Halpin-Tsai micromechanical model to evaluate the clay dispersion in clay-reinforced polyethylene nanocomposites / N. Uyanik in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 28-34 Titre : Application of the experimental results to the modified Halpin-Tsai micromechanical model to evaluate the clay dispersion in clay-reinforced polyethylene nanocomposites Type de document : texte imprimé Auteurs : N. Uyanik, Auteur Année de publication : 2014 Article en page(s) : p. 28-34 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Argile Copolymères greffés Dispersions et suspensions Essais dynamiques Itaconate de monométhyle Itaconique, Acide Matériaux hybrides Micromécanique (physique du solide) Montmorillonite Polyéthylène basse densité Polyéthylène basse densité linéaire Traction (mécanique) Index. décimale : 668.4 Plastiques, vinyles Résumé : Low-density polyethylene (LDPE)- and linear low-density polyethylene (LLDPE)-based polymer nanocomposites (PNC) containing organically modified montmorillonite (MMT) were prepared by melt mixing process. Itaconic acid (IA) and monomethyl itaconate (MMI) grafted polyethylene (PE) were used as compatibilizers. Na-MMT was modified by dodecyl-, hexadecyl-, and octadecyl-ammonium chlorides and then the compatibilizers were synthesized in solution reaction. 5 wt% organoclay and different concentration of compatibilizers (5, 10, and 15 wt%) were used for the PNC preparations to compare the effects of compatibilizers. The interlayer spacings, d001, and the mechanical properties of samples were measured by XRD analysis and universal testing machine, respectively. The experimental tensile moduli were used in Halpin-Tsai micro mechanical model to obtain "l/t" ratios and the results were compared experimental d001 values obtained from XRD data. It was found that the experimental results are in good agreement with the calculated results. Note de contenu : - Materials - Analyses and characterizations - Preparation of nanocomposites - Calculation methods DOI : 10.3139/217.2797 En ligne : https://drive.google.com/file/d/1MZvk_r77JHArJ_7ztxoqUozjEAu2kK8r/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20572 [article]

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Influence of solvent washing and soxhlet extraction on the thermal stability of organically modified layered silicates / T. Mariappan in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 35-40 Titre : Influence of solvent washing and soxhlet extraction on the thermal stability of organically modified layered silicates Type de document : texte imprimé Auteurs : T. Mariappan, Auteur ; Charles A. Wilkie, Auteur Année de publication : 2014 Article en page(s) : p. 35-40 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Alcool Argile Eau Extraction par solvant Méthanol Nettoyage Silicates Stabilité thermique Index. décimale : 668.4 Plastiques, vinyles Résumé : An efficacious process for removing excess surfactant and sodium halide from an organically-modified clay is described in this paper. Improved thermal stability of the organoclay is observed using both washing with ethanol or Soxhlet extraction with methanol. The selection of the solvent to be used plays a vital role in removing the excess organic modifier from the organoclay. Approximately a 60 °C increment in onset thermal stability (T5%) is observed by solvent washing while a further 20 °C improvement is seen using Soxhlet extraction. Washing with hot deionized water followed by an ethanol washing will remove the excess modifier more effectively than does hot DI water and THF. Note de contenu : - EXPERIMENTAL : Materials - Clay modification - Measurements - RESULTS AND DISCUSSION : Effect of solvent washing - Effect of soxhlet extraction DOI : 10.3139/217.2798 En ligne : https://drive.google.com/file/d/14kUR8kWoYiOKbHZppMCaRbHA3gbNvl4B/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20573 [article]

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Effect of screw rotation speed on the properties of polycarbonate/vapor-grown carbon fiber composites prepared by melt compounding / Shuichi Tanoue in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 41-50 Titre : Effect of screw rotation speed on the properties of polycarbonate/vapor-grown carbon fiber composites prepared by melt compounding Type de document : texte imprimé Auteurs : Shuichi Tanoue, Auteur ; J. Nithikaranjanatharn, Auteur ; H. Okuzono, Auteur ; H. Ueda, Auteur ; Hideyuki Uematsu, Auteur ; Y. Iemoto, Auteur Année de publication : 2014 Article en page(s) : p. 41-50 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites à fibres de carbone à croissance en phase vapeur Déformations (mécanique) Essais dynamiques Extrudeuse bi-vis Mouvement rotatoire Polycarbonates Rupture (mécanique) Traction (mécanique) Index. décimale : 668.4 Plastiques, vinyles Résumé : The effect of screw rotation speed on the mechanical property and thermal conductivity of polycarbonate (PC)/vapor-grown carbon fiber (VGCF) composites prepared by a twin screw extruder was discussed in this paper. Two types of VGCF (VGCF-H, the aspect ratio of 40, and VGCF-S, the aspect ratio of 100) were used. In the tensile test, the breaking pattern of PC composite changed to brittle failures by adding VGCF-H irrespective of screw rotation speed. Young's modulus of PC/VGCF-H slightly increased with the screw rotation speed. On the other hands, the breaking strain of PC/VGCF drastically decreased above 150 min?1. Young's modulus of PC/VGCF-S slightly increased with screw rotation speed until 150 min?1, however, it decreased at 175 min?1. The thermal conductivity of PC/VGCF-H was independent of the screw rotation speed. In contrast, the thermal conductivity of PC/VGCF-S gradually increased with screw rotation speed until 150 min?1 and it also decreased at 175 min?1. From the SEM observation and rheological behavior, the dispersion state of VGCF-H in PC/VGCF-H was independent of the screw rotation speed. On the other hands, the network structures of VGCF-S were observed in PC/VGCF-S and the state of these network structures depended on the screw rotation speed. It was clarified that the mechanical property and thermal conductivity of PC/VGCF were attributable to the dispersion state of VGCF. Note de contenu : - Mechanical property and thermal conductivity - Evaluation of dispersion state of VGCF DOI : 10.3139/217.2799 En ligne : https://drive.google.com/file/d/1KAe1qYfjaYPZuimZ86w5le82-luirDQE/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20574 [article]

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Simulation of co-rotating twin screw extrusion process subject to pressure-dependent wall slip at barrel and screw surfaces : 3D FEM analysis for combinations of forward- and reverse-conveying screw elements / M. Malik in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 51-62 Titre : Simulation of co-rotating twin screw extrusion process subject to pressure-dependent wall slip at barrel and screw surfaces : 3D FEM analysis for combinations of forward- and reverse-conveying screw elements Type de document : texte imprimé Auteurs : M. Malik, Auteur ; Dylan M. Kalyon, Auteur ; J. C. Golba, Auteur Année de publication : 2014 Article en page(s) : p. 51-62 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Ecoulement visqueux Eléments finis, Méthode des Extrudeuse bi-vis Matières plastiques -- Extrusion Modèles mathématiques Simulation par ordinateur Index. décimale : 668.4 Plastiques, vinyles Résumé : Mathematical modeling and simulation of the coupled flow, deformation, heat and mass transfer, and rate of reactions occurring in the twin screw extruder allow the optimization of process parameters and the screw and barrel geometries. In mathematical modeling of the twin screw extrusion process the conventional flow boundary condition at the screw and barrel walls is the no-slip condition. However, most complex fluids, including polymers, polymeric suspensions and blends, exhibit wall slip, with the slip behavior depending on the intrinsic properties of the materials being processed, the operating conditions, the geometries of the barrel, screw and the die, and the properties of the solid surfaces. Typically, the slip velocity is specified to be a function of temperature, stress condition at the wall and the materials of construction. However, recent investigations have further revealed that the wall slip behavior can also be significantly affected by pressure. With an objective of considering the effects of wall slip on the dynamics of twin screw extrusion, fully-intermeshing co-rotating twin screw extrusion of a concentrated suspension is analyzed using three-dimensional finite element method, FEM, subject to the wall slip boundary condition. The wall slip boundary condition is first applied systematically to barrel and screw surfaces individually followed by the application of wall slip to both surfaces simultaneously. In an integrated fashion both the forward-conveying (pressure-generating) and reverse-conveying (pressure-losing) screw sections are considered. The effects of pressure on wall slip are also analyzed and elucidated. Note de contenu : - MATHEMATICAL MODEL OF THE FULLY-INTERMESHING CO-ROTATING TWIN SCREW EXTRUSION PROCESS : Geometry - Regularization of the viscoplastic constitutive equation - FEM analysis - Wall slip boundary condition DOI : 10.3139/217.2802 En ligne : https://drive.google.com/file/d/1Xvzy_QPFV7SHpPjW82F07IHhyR3ykRmG/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20575 [article]

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Preparation of polymer-clay nanocomposites by melt mixing in a twin screw extruder : using on-line SAOS rheometry to assess the level of dispersion / S. Mould in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 63-70 Titre : Preparation of polymer-clay nanocomposites by melt mixing in a twin screw extruder : using on-line SAOS rheometry to assess the level of dispersion Type de document : texte imprimé Auteurs : S. Mould, Auteur ; J. Barbas, Auteur ; A. V. Machado, Auteur ; J. M. Nóbrega, Auteur ; Jose A. Covas, Auteur Année de publication : 2014 Article en page(s) : p. 63-70 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Argile Dispersions et suspensions Etat fondu (matériaux) Extrudeuse bi-vis Matériaux hybrides Mélange Polypropylène Rhéologie Index. décimale : 668.4 Plastiques, vinyles Résumé : A prototype on-line rotational rheometer was fixed between a twin screw extruder and a multi-rod die of an industrial pelletization line used for the manufacture of polymer-clay nanocomposites. After diverting the required amount of melt to the device, measurements were performed in small amplitude oscillatory shear and used to estimate the level of dispersion of the organoclay in the polypropylene matrix, by means of correlations that are commonly utilized. The aim is to determine whether changes in clay type, clay content, feed rate and screw speed cause detectable alterations in the rheological response and thus in the level of dispersion, with a view to practical process monitoring and control. The analysis of the data is supported by XRD and electron (scanning and transmission) microscopy observations. Note de contenu : - On-line vs. off-line measurements - Effet of clay type - Effect of clay content - Effect of feed rate - Effect of screw speed DOI : 10.3139/217.2803 En ligne : https://drive.google.com/file/d/1jxKahrZ801pPXJ4XyjUWUPVYbu4ZwSXo/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20576 [article]

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Residence time distribution in a high shear twin screw extruder / E. Fel in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 71-80 Titre : Residence time distribution in a high shear twin screw extruder Type de document : texte imprimé Auteurs : E. Fel, Auteur ; Valérie Massardier, Auteur ; F. Melis, Auteur ; Bruno Vergnes, Auteur Année de publication : 2014 Article en page(s) : p. 71-80 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Cisaillement (mécanique) Distribution de temps de séjour Extrudeuse bi-vis Polypropylène Simulation par ordinateur Index. décimale : 668.4 Plastiques, vinyles Résumé : The residence time distributions (RTD) of a high shear twin screw extruder were measured by an on–line UV fluorescence device. First, by increasing throughput (Q) and screw speed (N), a decrease of the complex viscosity of the studied polypropylene (PP) was observed, revealing chain scissions. It was associated to high viscous dissipation taking place during extrusion, and more particularly under high shear conditions. Then the impact of these experimental conditions on the RTD was carried out. As expected, an increase of usual throughputs and screw speeds decrease mostly the RTD characteristic data. In this study industrial rate have been studied: throughput varied from 1.5 up to 22 kg h?1 and screw speed varied from 200 min?1 up to 1 200 min?1. However, by increasing the screw speed over usual values (from 500 up to 1 200 min?1), the variation of some experimental RTD characteristics were unexpected. Indeed, the slope of the shape of the experimental RTD function E(t) changed significantly. This phenomenon will be called lag or delay time. This result was only observed at low throughputs and high screw rotation speeds. To finish, a modeling software of twin screw extrusion process was used to compare experimental and calculated results. For usual processing conditions (up to 700 min?1), the simulation predicts nicely the experimental RTDs. However, at high screw speed (N > 800 min?1) and moderate throughput (Q = 4 kg h?1), the simulation fails to predict the RDT delay time. Hence, some side effects apparently occurred during high shear extrusion at low throughputs. Note de contenu : - THEORETICAL ASPECTS : Residence time distribution (RTD) - MATERIALS AND METHODS : Material - Twin screw extruder - UV tracer and UV-fluorescence device - Bulk temperature - RESULTS AND DISCUSSION : Experimental results - Simulation from Ludovic software DOI : 10.3139/217.2805 En ligne : https://drive.google.com/file/d/1o_Iuqwuk5vId94nbqcSHDVbikBJ84ssh/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20577 [article]

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PVDF/carbon nanotubes/nanoclay composites for piezoelectric applications / F. Sadeghi in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 81-87 Titre : PVDF/carbon nanotubes/nanoclay composites for piezoelectric applications Type de document : texte imprimé Auteurs : F. Sadeghi, Auteur ; A. Sarvi, Auteur Année de publication : 2014 Article en page(s) : p. 81-87 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Argile Conduction électrique Matériaux piézoélectriques Nanoparticules Nanotubes Polyfluorure de vinylidène Index. décimale : 668.4 Plastiques, vinyles Résumé : Poly(vinylidene) fluoride (PVDF) nanocomposite samples were prepared by incorporation of carbon nanotubes (CNT) and nanoclay into PVDF using a twin screw extruder. Carbon nanotube was added to improve electrical conductivity and nanoclay was included to enhance ? crystal formation for piezoelectric property. X-ray diffraction (XRD) results showed that partial melt intercalation of PVDF in clay was achieved. The XRD results also revealed that CNT and nanoclay addition increased ? phase crystal amount in PVDF. FTIR spectroscopy measurements confirmed the XRD results and showed that the effect of nanoclay on ? phase crystal formation of PVDF was more prominent than CNT. It was found that shear rate applied during crystallization would improve ? phase crystal formation but only for the neat PVDF. Electrical conductivity results showed that addition of CNT improved conductivity as a percolation of 2 wt.% was observed. It was found that dispersion of CNT into PVDF matrix is very crucial for obtaining a higher conductivity. The results showed that clay incorporation into CNT nanocomposite improved electrical conductivity. The TEM micrographs showed bundles of CNT were adhered to clay particles. That was considered an indication of affinity between CNT and organically modified clay. The results of compounding of CNT and nanoclay with PVDF in batch mixer also revealed improvement in electrical conductivity when clay was added into PVDF/CNT composite in melt state. The conductivity improved with mixing time for both systems: PVDF/CNT and PVDF/CNT/nanoclay. DOI : 10.3139/217.2814 En ligne : https://drive.google.com/file/d/1YsykA23ulz28dDPDMkD1Q1fvS2H_zcv4/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20578 [article]

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Viscoelastic and electrical properties of carbon nanotubes filled poly(butylene succinate) in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 88-94 Titre : Viscoelastic and electrical properties of carbon nanotubes filled poly(butylene succinate) Type de document : texte imprimé Année de publication : 2014 Article en page(s) : p. 88-94 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Composites -- Propriétés électriques Composites -- Propriétés thermomécaniques Conduction électrique Nanotubes Polybutylène succinate Viscoélasticité Index. décimale : 668.4 Plastiques, vinyles Résumé : The carbon nanotubes (CNTs)-containing composites of poly(butylene succinate) (PBS) were prepared by melt-blending in a batch mixer with three concentrations by weight of CNTs: 1, 2 and 3 %. State of dispersion-distribution of the CNTs in the PBS matrix was examined by electron microscopic observations that revealed homogeneous distribution of agglomerated CNTs in PBS matrix. The dynamic mechanical studies demonstrated an increase in the storage modulus of PBS matrix with the CNTs loading. Melt-state rheological properties measurements were found to be modified with CNT loading changing from liquid-like, to gel-like and then to viscoelastic solid-like. Finally, the in-plane electrical conductivity was found to be substantially enhanced with CNT loading, whereas the through-plane conductivity was found to be only slighted increased with the CNT loading. Such changes in viscoelastic properties along with the improvements in both thermomechanical and electrical properties are expected to open opportunities for the use of PBS extending its applications from the classical field of packaging to new niches such as tissue-engineering. Note de contenu : - EXPERIMENTAL : Materials - PBS/CNT composite processing - Surface morphology and dispersion characteristic - Dynamic property measurement - Melt rheology - Electrical property - RESULTS AND DISCUSSIONS : Analyses of the state of dispersion and distribution of CNTs - Dynamic mechanical properties - Melt-state rheology - Electrical conductivity DOI : 10.3139/217.2812 En ligne : https://drive.google.com/file/d/1l8NQq7-s8J5tWNeI9tN_b2bMeeAhJEnJ/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20579 [article]

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Sealibility and seal characteristics of PE/EVA and PLA/PCL blends / Z. Najarzadeh in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 95-102 Titre : Sealibility and seal characteristics of PE/EVA and PLA/PCL blends Type de document : texte imprimé Auteurs : Z. Najarzadeh, Auteur ; R. Y. Tabasi, Auteur ; Abdellah Ajji, Auteur Année de publication : 2014 Article en page(s) : p. 95-102 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Alliages polymères Copolymère éthylène acétate de vinyle Joints d'étanchéité Poly-e-caprolactone Polyesters Polyéthylène Polylactique, Acide L'acide polylactique (anglais : polylactic acid, abrégé en PLA) est un polymère entièrement biodégradable utilisé dans l'alimentation pour l'emballage des Å“ufs et plus récemment pour remplacer les sacs et cabas en plastiques jusqu'ici distribués dans les commerces. Il est utilisé également en chirurgie où les sutures sont réalisées avec des polymères biodégradables qui sont décomposés par réaction avec l’eau ou sous l’action d’enzymes. Il est également utilisé pour les nouveaux essais de stent biodégradable. Le PLA peut-être obtenu à partir d'amidon de maïs, ce qui en fait la première alternative naturelle au polyéthylène (le terme de bioplastique est utilisé). En effet, l'acide polylactique est un produit résultant de la fermentation des sucres ou de l'amidon sous l'effet de bactéries synthétisant l'acide lactique. Dans un second temps, l'acide lactique est polymérisé par un nouveau procédé de fermentation, pour devenir de l'acide polylactique. Ce procédé conduit à des polymères avec des masses molaires relativement basses. Afin de produire un acide polylactique avec des masses molaires plus élevées, l'acide polylactique produit par condensation de l'acide lactique est dépolymérisé, produisant du lactide, qui est à son tour polymérisé par ouverture de cycle. Le PLA est donc l’un de ces polymères, dans lequel les longues molécules filiformes sont construites par la réaction d’un groupement acide et d’une molécule d’acide lactique sur le groupement hydroxyle d’une autre pour donner une jonction ester. Dans le corps, la réaction se fait en sens inverse et l’acide lactique ainsi libéré est incorporé dans le processus métabolique normal. On obtient un polymère plus résistant en utilisant l'acide glycolique, soit seul, soit combiné à l’acide lactique. Polymères aliphatiques Index. décimale : 668.9 Polymères Résumé : Seal strength behavior of low density polyethylene and ethylene vinyl acetate copolymer (PE/EVA) blends as well as that of blends of a seal grade PLA with aliphatic polyester (PCL) was studied. Polyethylene is commonly used for seal application in packaging multilayer structures and amorphous PLA is considered to be its counterpart for compostable and/or biodegradables ones. Incorporation of EVA in polyethylene improves its sealability in terms of a decrease in seal initiation temperature and broadness of sealability plateau. This was interpreted as due to the formation of finer crystals, a decrease in the melting point and presence of vinyl acetate polar group. These were supported by results obtained from differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). For the PLA/PCL system, the dispersed phase was stretched into elongated ellipsoidal domains. This type of morphology affected the mechanical and seal properties of the blends. As a result of blending, both hot-tack initiation temperature and strength as well as seal initiation temperature were enhanced. The enhancement in these seal properties was significant when the concentration of the dispersed phase exceeded 20 wt% in the blend. Hot-tack strength of up to twice of pure PLA was achieved through blending. This was attributed to the lower glass transition temperature of PCL, resulting in enhanced mobility of PLA chains and also the high aspect ratio of the dispersed phase. The maximum obtained hot-tack strength (1 200 g/25 mm) at 40 % dispersed content compared advantageously to commercially available polyolefin based sealant resins. The seal and hot-tack initiation temperatures were shifted to lower temperatures by as much as 30 °C, which can allow faster and more energy efficient sealing process. Note de contenu : - RESULTS AND DISCUSSION FOR PE/EVA SYSTEM : Differential scanning calorimetry (DSC) results - Sealibility results - Blend morphology - RESULTS AND DISCUSSION FOR PLA/PCL SYSTEM : Blend morphology - Thermal analysis results - Sealibility DOI : 10.3139/217.2813 En ligne : https://drive.google.com/file/d/1NKzOc3TI1Ut-YWHzaIwNby9E5E3kfUif/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20580 [article]

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Effects of polymer viscosity and nanofillers on morphology of nanofibers obtained by a gas jet method / J.-H. Shang in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 103-111 Titre : Effects of polymer viscosity and nanofillers on morphology of nanofibers obtained by a gas jet method Type de document : texte imprimé Auteurs : J.-H. Shang, Auteur ; R. E. Benavides, Auteur ; Sadhan C. Jana, Auteur Année de publication : 2014 Article en page(s) : p. 103-111 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Charges (matériaux) Morphologie (matériaux) Nanofibres Nanoparticules 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. Poids moléculaires Polyacétate de vinyle Polyéthylène glycol Polymères en émulsion Polyvinylpyrrolidone Viscosité Index. décimale : 668.4 Plastiques, vinyles Résumé : This research evaluates the effects of molecular weight, polymer solution concentration, and carbon nanotube concentration on diameter distribution of polymer nanofibers produced with gas jet fiber (GJF) method. In GJF method, the shear and extensional forces of high-velocity gas jets are used to spin fibers from polymer solutions. The correlation between polymer molecular weight and fiber diameter distribution is studied along with the effect of multi-walled carbon nanotubes (MWCNT) on fiber diameter distribution. The paper also assesses how carbon nanotubes distribute in bi-component polymer nanofibers. It is found that polymer chain entanglement is a key determinant of fiber diameter. MWCNTs do not show preference for distribution in polyvinylidene pyrrole (PVP) and polyvinylacetate (PVAc) and instead appear on the surfaces of the fibers. A negative value of spreading coefficient supports this observation. Note de contenu : - Diameter and morphology of PEO nanofibers and microfibers by GJF method - Effects of carbon nanotubes on single component polymer nanofibers - Distribution of carbon nanotubes in bi-component polymer nanofibers DOI : 10.3139/217.2817 En ligne : https://drive.google.com/file/d/1wQGdWi-sDRXkW_ozpB3zMqdRxLSKRYqW/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20581 [article]

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Modeling of the torque requirements for the mixing and dispersion of silica into rubber / Y. Y. Law in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 112-117 Titre : Modeling of the torque requirements for the mixing and dispersion of silica into rubber Type de document : texte imprimé Auteurs : Y. Y. Law, Auteur ; Donald L. Feke, Auteur ; Ica Manas-Zloczower, Auteur Année de publication : 2014 Article en page(s) : p. 112-117 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Caoutchouc styrène-butadiène Dispersions et suspensions Elastomères Mélange Silice La silice est la forme naturelle du dioxyde de silicium (SiO2) qui entre dans la composition de nombreux minéraux. La silice existe à l'état libre sous différentes formes cristallines ou amorphes et à l'état combiné dans les silicates, les groupes SiO2 étant alors liés à d'autres atomes (Al : Aluminium, Fe : Fer, Mg : Magnésium, Ca : Calcium, Na : Sodium, K : Potassium...). Les silicates sont les constituants principaux du manteau et de l'écorce terrestre. La silice libre est également très abondante dans la nature, sous forme de quartz, de calcédoine et de terre de diatomée. La silice représente 60,6 % de la masse de la croûte terrestre continentale. Viscosité Index. décimale : 668.4 Plastiques, vinyles Résumé : A model for the evolution of torque requirements in the batch mixing of silica agglomerates in styrene-butadiene rubber has been developed. The analysis considers the rheology of suspensions as modeled by the Krieger-Dougherty equation but with modifications so that it can apply to a wider range of solids loading, and combines that with a separate model that expresses the kinetics of the dispersion of silica agglomerates. The model shows good agreement with the trends of experimental data, and thus can be used to make predictions about torque requirements for compounding commercial grades of silica into rubber, as related to dispersion, under practical mixing conditions. Note de contenu : - Mixing torque - Viscosity model - Dispersion model - Mixing strain DOI : 10.3139/217.2818 En ligne : https://drive.google.com/file/d/10JwoM4YwzAOeJmpa4pVSxz-DZrSsZ-Py/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20582 [article]

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High shear processing of (PP/EPR)/silica nanocomposites : improvement of morphology and properties / M. Louizi in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 118-127 Titre : High shear processing of (PP/EPR)/silica nanocomposites : improvement of morphology and properties Type de document : texte imprimé Auteurs : M. Louizi, Auteur ; Valérie Massardier, Auteur ; F. Melis, Auteur ; P. Alcouffe, Auteur ; Philippe Cassagnau, Auteur Année de publication : 2014 Article en page(s) : p. 118-127 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Allongement à la rupture Caoutchouc Cisaillement (mécanique) Composites -- Propriétés mécaniques Copolymère éthylène propylène Elastomères Morphologie (matériaux) Nanoparticules Polypropylène Résistance au chocs Rhéologie Résumé : The aim of this article is to upgrade the performance of polypropylene/ethylene propylene rubber (PP/EPR) blends by addition of hydrophobic nanosilica (SiR805) and using "high shear processing technology". The morphological developments, mechanical and rheological properties of these composites were investigated as a function of processing conditions. High shear processing has proved to be an efficient process to decrease the size of the dispersed phase (EPR) up to 300 nm and to disperse finely nanosilica particles to less than 30 nm especially at 800 min?1. Moreover, the morphology stability of the nanocomposite is ascribed to the formation of a core shell structure (EPR nodules = core; nano-silica = shell) and selective location of nanosilica at the interface. More importantly, this core-shell structure is favoured to enhance the impact strength of the (PP/EPR)/3 wt% SiR805 nanocomposite. In agreement to the obtained morphology, the improvement (about 60 %) of elongation at break attests a good adhesion between phases due to high shear effect as highlighted by viscoelastic properties. Therefore, high shear processing technology has proved to be a relevant method to prepare nanocomposites with high performances without adding any additive and offers new perspectives for recycling and lightening structures. Note de contenu : - Materials - Nanocomposites preparation - Morphology characterization - Rheological analysis - Mechanical properties DOI : 10.3139/217.2819 En ligne : https://drive.google.com/file/d/1-WiX6aZP71Yks8UZWiPU5gZihEK2IjsT/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20583 [article]

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An overview of molten polymer drawing instabilities / Y. Demay in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 1 (03/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 1 (03/2014) . - p. 128-129 Titre : An overview of molten polymer drawing instabilities Type de document : texte imprimé Auteurs : Y. Demay, Auteur ; Jean-François Agassant, Auteur Année de publication : 2014 Article en page(s) : p. 128-129 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Défauts Fibres textiles synthétiques Filature Films plastiques Instabilités (physique) Matières plastiques -- Soufflage Polyéthylène basse densité Polyéthylène basse densité linéaire Index. décimale : 668.4 Plastiques, vinyles Résumé : Drawing instabilities and rupture are a serious limitation in polymer fibre and film processing. Draw resonance and fibre or film rupture depend on the processing conditions, heat transfer and on the rheology of the polymer and some of these defects may also be encountered for Newtonian fluids. This paper reviews the different instabilities observed in fibre spinning, cast-film and film blowing. The time dependent equations are presented for the simplified situation of constant width cast-film and two modelling strategies, linear stability analysis and direct simulation, are proposed and then applied to the different fibre and film processes. Note de contenu : - MODELLING STRATEGY : CONSTANT WITH CAST-FILM PROCESS - CAST-FILM PROCESS : Influence of cooling - Influence of the nieck-in phenomenon - Validity of the membrane model : 2D transverse simulation - FIBRE SPINNING DOI : 10.3139/217.2832 En ligne : https://drive.google.com/file/d/1k_l4Kx4EG4wtvZoULUHuq3lnuFR9ROAm/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=20584 [article]

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