Effect of sparse long-chain branching on the film-casting behavior for a series of well-defined HDPEs / C. D. McGrady in INTERNATIONAL POLYMER PROCESSING, Vol. XXIV, N° 5 (11/2009)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIV, N° 5 (11/2009) . - p. 428-438 Titre : Effect of sparse long-chain branching on the film-casting behavior for a series of well-defined HDPEs Type de document : texte imprimé Auteurs : C. D. McGrady, Auteur ; C. W. Seay, Auteur ; D. G. Baird, Auteur Année de publication : 2009 Article en page(s) : p. 428-438 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The effect of sparse long chain branching, LCB, on the film-casting process is analyzed using a molecular model for the rheological behavior for a series of well-characterized, high-density polyethylene (HDPE) resins and a low-density polyethylene (LDPE) resin at various drawdown ratios. A full rheological characterization in both shear and shear-free flows is also presented. At low drawdown ratios, the LDPE exhibited the least degree of necking at distances less than the HDPE frostline. The sparsely-branched HDPE resins films had similar final film-widths that were larger than those of the linear HDPE. As the drawdown ratio was increased, film width profiles separated based on branching level. Small amounts of LCB were found to reduce the amount of necking at intermediate drawdown ratios. At higher drawdown ratios, the sparsely-branched HDPE resins of lower LCB content had film-widths that mimicked that of the linear HDPE, while the sparsely-branched HDPE resins of higher LCB content retained a larger film width. Molecular structural analysis via the Pom-Pom constitutive model suggested that branching that was distributed across a larger range of backbone lengths served to improve resistance to necking. As the drawdown ratio increased, the length of the backbones dominating the response decreased, so that the linear chains were controlling the necking behavior of the sparsely-branched resins of lower LCB content while remaining in the branched regime for higher LCB content HDPEs. Other processing variables such as shear viscosity magnitude, extrudate swell, and non-isothermal processing conditions were eliminated as contributing factors to the differences in the film width profile. DOI : 10.3139/217.2291 En ligne : https://drive.google.com/file/d/1Pb5a1KuePCmq0916W3J6UgkiB-hrU5Eu/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=6366 [article]

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Effects of sparse long chain branching on the spinning stability of LLDPEs / M. J. Bortner in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 3 (09/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 3 (09/2004) . - p. 236-243 Titre : Effects of sparse long chain branching on the spinning stability of LLDPEs Type de document : texte imprimé Auteurs : M. J. Bortner, Auteur ; P. J. Doerpinghaus, Auteur ; D. G. Baird, Auteur Année de publication : 2004 Article en page(s) : p. 236-243 Note générale : Bibliogr. Langues : Anglais (eng) Tags : Polymérisation  'Modèle  mathématique'  'Réaction  cinétique'  'Contrôle  du  process' Index. décimale : 668.9 Polymères Résumé : The influence of sparse long chain branching on the onset and propagation of isothermal draw resonance in fiber spinning of polyethylene melts was investigated. Six polyethylene melts were used in this study: three sparsely branched metallocene polyethylenes, a linear low-density metallocene polyethylene, a conventional linear low-density polyethylene, and a conventional low-density polyethylene (LDPE). The sparsely branched metallocene polyethylenes have almost identical shear rheology and molecular weight distributions, but strain harden to different extents under extensional deformation because of slight differences in the amount of sparse long chain branching. Critical draw ratios and the ratios of minimum to maximum diameter were found to be different for each of these polyethylenes. The two linear low-density polyethylenes, which have no long chain branching, had critical draw ratios similar to those of the sparsely branched polyethylenes, but failed (necked to the point of filament breakage) during monofilament extrusion at draw ratios significantly lower than those measured for the sparsely branched polyethylenes. In contrast, the LDPE, which has the highest degree of branching and largest molecular weight distribution, had a much higher critical draw ratio than that obtained for the other five polyethylenes. These results suggest that the degree of extensional strain hardening, arising from differences in long chain branching, has a significant effect on the onset and propagation of draw resonance in isothermal fiber spinning. In the case of LLDPE, broadening the MWD seemed to affect the drawability of LLDPE, but had no effect on the critical draw ratio. DOI : 10.3139/217.1824 En ligne : https://drive.google.com/file/d/14lw0WGF1EEAwBC_lYnaIoybbhYw7EEPi/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3105 [article]

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Extrusion blow molding of polymeric blends based on thermotropic liquid crystalline polymer and high density polyethylene / C. Qian in INTERNATIONAL POLYMER PROCESSING, Vol. XXXII, N° 1 (03/2017)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXII, N° 1 (03/2017) . - p. 112-120 Titre : Extrusion blow molding of polymeric blends based on thermotropic liquid crystalline polymer and high density polyethylene Type de document : texte imprimé Auteurs : C. Qian, Auteur ; C. D. Mansfield, Auteur ; D. G. Baird, Auteur Année de publication : 2017 Article en page(s) : p. 112-120 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Alliages polymères Alliages polymères -- propriétés mécaniques Anhydride maléique Bouteilles en matières plastiques Cristaux liquides thermotropes Matières plastiques -- Moulage par extrusion-soufflage Morphologie (matériaux) Polyéthylène haute densité Polymères cristallins Stabilité thermique Viscosimétrie Index. décimale : 668.4 Plastiques, vinyles Résumé : This work is concerned with the extrusion blow molding of polymeric blends containing thermotropic liquid crystalline polymer (TLCP) and high density polyethylene (HDPE), using a single screw extruder. The TLCP is synthesized from terephthalic acid, 4-hydroxybenzoic acid, hydroquinone and hydroquinone derivatives, the melting point of which is 280 °C. Because the TLCP is usually processed at much higher temperatures than HDPE, the thermal stability of HDPE at elevated temperature is evaluated. It is shown that HDPE is relatively stable in the processing temperature range of the TLCP used in this work (260 to 300 °C). Bottles are successfully produced from the blends containing 10, 20 and 50 wt% TLCP. The TLCP/HDPE blend bottles exhibit enhanced modulus relative to pure HDPE. However, the improvement in tensile strength is marginal. At 10 and 20 wt% TLCP contents, the TLCP phase exists as platelets aligning along the machine direction, while a co-continuous morphology is observed for the blend containing 50 wt% TLCP. To further enhance the mechanical properties of the blends, the preliminary effectiveness of maleic anhydride grafted HDPE (MA-g-HDPE) as a compatibilizer is studied. The injection molded ternary blends of TLCP/HDPE/MA-g-HDPE have demonstrated superior mechanical properties over the binary TLCP/HDPE blends, which suggests MA-g-HDPE as a potential compatibilizer for developing high performance TLCP/HDPE containers with enhanced mechanical properties. Note de contenu : - EXPERIMENTAL : Materials - Thermal stability measurements of HDPE - Melt compounding of the TLCP/HDPE blends - Viscosity measurements - Extrusion blow molding of the TLCP/HDPE blends - Injectionmolding of the ternary TLCP/MA-GHDPE/HDPE blends - Tensile properties - Morphological characterization - RESULTS AND DISCUSSION : Thermal stability of HDPE - Viscosity scheme of the TLCP/HDPE blends - Mechanical properties of the TLCP/HDPE bottles - Morphology of blow molded TLCP/HDPE bottles - Mechanical properties of the ternary TLCP/HDPE/MA-G-HDPE blends DOI : 10.3139/217.3293 En ligne : https://drive.google.com/file/d/1r_T4Ppz_MyY6lu4J3cG9VsCR219sMdT_/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28007 [article]

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Identifying melt processing conditions for a polyacrylonitrile copolymer plasticized with water, acetonitrile and their mixtures / Yu Jianger in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 3 (07/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 3 (07/2019) . - p. 307-313 Titre : Identifying melt processing conditions for a polyacrylonitrile copolymer plasticized with water, acetonitrile and their mixtures Type de document : texte imprimé Auteurs : Yu Jianger, Auteur ; G. C. Miller, Auteur ; J. S. Riffle, Auteur ; D. G. Baird, Auteur Année de publication : 2019 Article en page(s) : p. 307-313 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Acétonitrile L'acétonitrile, ou cyanure de méthyle, est un composé chimique de formule CH3CN. Ce liquide incolore, d'odeur sucrée, est le nitrile organique le plus simple, et très souvent utilisé en tant que solvant. Production et applications industrielles : L'acétonitrile est obtenu comme sous-produit de la production de l'acrylonitrile, c'est pourquoi la tendance à la production d'acétonitrile suit généralement celle de L'acrylonitrile. L'acétonitrile est utilisé comme solvant, notamment dans l'industrie pharmaceutique, mais également comme intermédiaire réactionnel dans la production de bon nombre de substances chimiques des pesticides aux parfums. Usages en laboratoire : C'est un solvant de choix pour tester une réaction chimique inconnue. Il est polaire, et son domaine liquide est assez étendu ce qui le rend commode. Il dissout une large gamme de composés sans encombre, conséquemment à la présence de protons non acides. L'acétone présente les mêmes propriétés mais elle est plus acide et plus réactive envers les bases et les nucléophiles. En chimie inorganique, l'acétonitrile est très employé comme ligand, abrégé MeCN. On l'utilise par exemple sous la forme PdCl2(MeCN)2 préparé en chauffant à reflux du dichlorure de palladium dans l'acétonitrile. C'est un solvant commun en voltampérométrie cyclique en raison de sa constante diélectrique relativement élevée. L'acétonitrile est aussi souvent utilisée en chromatographie en phase liquide, où il sert de phase mobile pour la séparation de molécules. Précautions : Il est nocif et inflammable. Il peut pénétrer par voie orale, cutanée ou par inhalation. Il est métabolisé en acide cyanhydrique et thiocyanate. Analyse thermique Copolymères Eau Extrusion filage Fusion, Points de Plastifiants Polyacrylonitrile Rhéologie Viscosité Index. décimale : 668.4 Plastiques, vinyles Résumé : This paper discusses the feasibility of the melt spinning process of polyacrylonitrile (PAN) copolymer (acrylonitrile/methylacrylate 95.6/4.4 mol% ratio) plasticized with H2O acetonitrile (ACN) and their mixture. The objective is to use water only as a plasticizer to melt spin PAN under specific conditions (composition, temperature etc.). The melting point and rheological measurements have been conducted by differential scanning calorimetry (DSC) and a modified capillary rheometer, respectively, for this plasticized system. The DSC results show that the melting point of the PAN copolymer can be reduced from over 300°C to below 180°C, which is the temperature for the onset of degradation (cyclization and crosslinking) of PAN. Rheological results show that the PAN copolymer can be extruded with a reasonable viscosity at 15 to 20°C above its melting point, and also the stability and viscosity are strongly dependent on temperature and the plasticizer type and content. Furthermore, the results indicate that the most appropriate condition for PAN melt spinning is for the PAN/H2O mixture of 70/30 wt% ratio at a temperature of 180°C for which the copolymer sample can remain stable without significant degradation for around 120 min and maintain its viscosity in the range of around 600 Pa s. Note de contenu : - EXPERIMENTAL : Materials - Sample preparation - Differential Scanning Calorimetry (DSC) - Rheological measurements - RESULTS AND DISCUSSION : Melting point results - Time-dependent viscosity results - Steady shear viscosity results DOI : https://doi.org/10.3139/217.3750 En ligne : https://www.degruyter.com/document/doi/10.3139/217.3750/pdf Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=32890 [article]

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Melt processability and foam suppression of high molecular weight polyethylenes plasticized with supercritical carbon dioxide / M. D. Wilding in INTERNATIONAL POLYMER PROCESSING, Vol. XXIII, N° 2 (05/2008)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIII, N° 2 (05/2008) . - p. 228-237 Titre : Melt processability and foam suppression of high molecular weight polyethylenes plasticized with supercritical carbon dioxide Type de document : texte imprimé Auteurs : M. D. Wilding, Auteur ; D. G. Baird, Auteur Année de publication : 2008 Article en page(s) : p. 228-237 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The purpose of this study is to determine to what extent CO2 can be used as a processing aid to melt process polyethylenes of higher molecular weight than can be typically melt processed. To assess the ability to melt process high molecular weight polyethylenes with CO2, the viscosity of a 460000 g/mol high density polyethylene (HDPE) plasticized with various amounts of absorbed CO2 in an extrusion process was determined using a slit die rheometer that was attached to the end of the extruder. A relationship was developed to determine the maximum molecular weight polyethylene that could be processed at a given viscosity reduction due to absorbed CO2. This relationship was tested by using CO2 to process a blend of 40 weight percent ultra-high molecular weight polyethylene (UHMWPE) and the 460000 g/mol HDPE which lead to an equivalent molecular weight of 720000 g/mol. The viscosity of the blend with 12 weight percent CO2 was reduced to that of the pure 460 000 g/mol HDPE as predicted by the relationship. Preliminary studies using a pressurized chamber attached to the exit of the die allowed one to assess the conditions under which suppression of foaming within fibers or other extruded forms is possible. DOI : 10.3139/217.2068 En ligne : https://drive.google.com/file/d/1svyDNCauW3-3M7Oqu2F8HBaOSstFPHwV/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2653 [article]

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Properties of injection molded in situ composites based on PPS and a melt processable glass / R. T. Young in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 3 (09/2000)  

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Simulation of injection molding using a model with delayed fiber orientation / G. M. Vélez-Garcia in INTERNATIONAL POLYMER PROCESSING, Vol. XXVI, N° 3 (07/2011)  

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Sparse long-chain branching's effect on the film-casting behavior of PE / C. W. Seay in INTERNATIONAL POLYMER PROCESSING, Vol. XXIV, N° 1 (03/2009)  

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Study of melt spinning processing conditions for a polyacrylonitrile copolymer with a water/ethanol mixture as a plasticizer / J. Yu in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 5 (11/2019)  

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