Study on viscoelastic behavior and extrusion blow molding processability of PP/PE blends / Seiji Shiromoto in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 3 (09/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 3 (09/2004) . - p. 287-295 Titre : Study on viscoelastic behavior and extrusion blow molding processability of PP/PE blends Type de document : texte imprimé Auteurs : Seiji Shiromoto, Auteur ; K. Koyama, Auteur Année de publication : 2004 Article en page(s) : p. 287-295 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : In this study, extrusion blow molding processability of polypropylene/polyethylene (PP/PE) blends was related to their viscoelastic behavior and morphology under shear flow. The propylene block-copolymer (PP-B) and blends comprising the PP-B and the linear low-density polyethylene (PE), weight fraction of the PE (PE) was up to 20 wt.%, were mainly used for this study. Viscoelastic behavior under shear flow and swelling ratio of the extruded strands were measured by using a capillary type rheometer. Morphology of the strands was observed by TEM. In case of the PP-B, swelling ratio highly depended on shear rate. Coarse aggregated droplets were observed irrespective of shear rate under the measurement. The droplets were ethylene-propylene copolymers (EP) included in the PP-B aggregated at conversing section of the capillary. However, in case of the PP-B/PE blends, swelling ratio showed lower dependence on shear rate as the PE was higher. When the shear rate was low, large droplets were observed and they were highly deformed in the flow direction. On the other hand, when shear rate was high, the droplets were smaller and showed no deformation in the flow direction because the droplets were broken up due to occurrence of high shear stress. Wall thickness of blow molded bottles produced from the PP-B/PE blends was not affected by the throughput rate. It was proportional to the die-core gap. On the other hand, wall thickness of bottles of the PP-B depended on the throughput rate and it was not proportional to the die-core gap. These results suggest that extrusion blow molding processability of polymer blends is good when the dependence of swelling ratio on shear rate is low. DOI : 10.3139/217.1828 En ligne : https://drive.google.com/file/d/1MS1dUMvHw7rdkao-MleLVvxDwmzi9NFV/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3112 [article]

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The mechanism of neck-in phenomenon in film casting process / Seiji Shiromoto in INTERNATIONAL POLYMER PROCESSING, Vol. XXIX, N° 2 (05/2014)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXIX, N° 2 (05/2014) . - p. 197-206 Titre : The mechanism of neck-in phenomenon in film casting process Type de document : texte imprimé Auteurs : Seiji Shiromoto, Auteur Année de publication : 2014 Article en page(s) : p. 197-206 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Effet de striction (physique) Polyéthylène basse densité Simulation par ordinateur Viscoélasticité Viscosité Index. décimale : 668.9 Polymères Résumé : In this study, the non-isothermal viscoelastic simulation of the film casting process was carried out. Low-density polyethylene polymerized by a high-pressure process (LDPE) was used for the simulation. The LDPE exhibited strain hardening in elongational viscosity since it has long chain branching. The Phan-Thien/Tanner model, as a constitutive equation of the viscoelastic fluid, and temperature dependence of the Arrhenius law were employed for the simulation to investigate the effect of viscoelasticity on extrusion drawing, so-called neck-in phenomenon. We developed the theoretical model on the basis of deformation type and force balance of a film to recognize the mechanism of the neck-in phenomenon. It was confirmed from a combination of the simulation results and the theoretical model that neck-in was determined by the ratio of planar to uniaxial elongational viscosity rather than the strain hardening nature of a uniaxial elongational viscosity. Note de contenu : - NUMERICAL SIMULATION : Simulation method - Processing conditions - Materials - Viscoelastic model - Viscous model - Temperature dependence - NECK-IN MODEL - RESULTS AND DISCUSSION : Verification of the neck-in model - The effect of viscoelasticity and process conditions on neck-in - The effect of viscosity on neck-in DOI : 10.3139/217.2784 En ligne : https://drive.google.com/file/d/1VDsHPRVFPLW1DsdihysfZ1JfMoTBjU2R/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=21313 [article]

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