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INTERNATIONAL POLYMER PROCESSING / Polymer Processing Society . Vol. XV, N° 4Mention de date : 12/2000Paru le : 01/12/2000 |
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Ajouter le résultat dans votre panierInjection blow molding technology for polyethylene terephthalate / R. A. Bubeck in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : Injection blow molding technology for polyethylene terephthalate Type de document : texte imprimé Auteurs : R. A. Bubeck, Auteur ; M. A. Barger, Auteur Année de publication : 2000 Article en page(s) : p. 337-342 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : A review of patents and the literature addressing the injection blow molding (IBM) technology specific to PET bottles and containers is presented. Fabrication and polymer modification issues were cited. It was found that there is no model that includes all factors which enables a complete a priori prediction of injection blow molded PET container performance, but there are several which cover certain aspects of the preform blowing step. Hot fill capability for PET is currently managed by both the control of crystallinity and container design considerations (i.e., wall profile, ribs, etc.). Depending on the desired result, both processing routes to enhance the level of crystallinity (generically referred to in the industry as heat set technology), and molecular modification to disrupt crystallinity have been patented, some quite recently. A number of patents address technologies that can be used to modify melt elasticity for blow molding. The modification of PET with PEN presents some new challenges due to transesterification during processing and fabrication. Biaxial stretch ratios of 18 are usually required for the blow molding of PET/PEN blends, and maximum filling temperature noticeably decreases only one day after fabrication. Note de contenu : - GENERAL FUNDAMENTALS AND APPLICABLE MODELS
- THE TECHNOLOGY OF INJECTION BLOW MOLDING OF PET : Processing technology for IBM of PET - Polymer modification of PET for IBM - Integrated handlesDOI : 10.3139/217.1616 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16143
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible A new polymer processing technology for polymer blends with unmatched viscosity : solid-state shear pulverization (S3P) / K. Khait in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : A new polymer processing technology for polymer blends with unmatched viscosity : solid-state shear pulverization (S3P) Type de document : texte imprimé Auteurs : K. Khait, Auteur ; J. M. Torkelson, Auteur Année de publication : 2000 Article en page(s) : p. 343-347 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Solid-State Shear Pulverization (S3P) is a new polymer processing technology capable of efficient mixing blends with different component viscosities (which are unprocessable by conventional melt extrusion due to the phase separation). S3P subjects polymers to compression and shear, resulting in fracture into a powder of various particle size and particle size distribution. S3P also allows modification of properties by compatibilization of ordinarily incompatible polymers without adding premade copolymers or conventional functional groups. Additionally, because S3P produces powder, it is suitable for a solid-state dispersion of pigments, curing agents, catalysts and other additives without melting (unlike conventional compounding).
After reviewing the S3P concept, this paper discusses recent experimental data. The research focuses on mixing like polymers such as virgin polypropylene (PP) with unmatched viscosity, resulting in blends with improved processability and a significant increase in elongation at break. A comparison with a conventional melt mixing by twin-screw extrusion is provided to demonstrate uniqueness of S3P processing. An additional example involves the mixing of dissimilar, ordinarily incompatible polymers such as recycled high-density polyethylene (PE-HD), low-density polyethylene (PE-LD), PP, polystyrene (PS), and polyvinyl chloride (PVC) with very different viscosities. Once again, the S3P-made material exhibited exceptionally high elongation at break as compared with that of the conventionally melt-mixed blend.DOI : 10.3139/217.1617 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16144
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible In-line density monitoring of rigid PVC foam during extrusion process / N. H. Abu-Zahra in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : In-line density monitoring of rigid PVC foam during extrusion process Type de document : texte imprimé Auteurs : N. H. Abu-Zahra, Auteur ; H. Chang, Auteur Année de publication : 2000 Article en page(s) : p. 348-354 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : An ultrasound-based sensor has been investigated to monitor the density of rigid PVC foam, in-line, during the extrusion process. A 2.25 MHz ultrasound transducer was used to measure the acoustic properties; i.e. speed of sound, acoustic impedance, and attenuation, in the polymer melt prior to exiting the extrusion die. A special transducer adapter and wave reflector were incorporated in the design of the extrusion die. The density of PVC foam was varied by varying the blowing agent content in the resin compound prior to extrusion. A mathematical derivation of the behavior of ultrasound waves in the melt is presented and used to calculate the attenuation coefficient of the polymer melt at various foam densities. An empirical relation was derived between the calculated attenuation coefficient of the polymer melt and the measured density of the foam extrudate. This relation can be used to estimate the foam density based on the acoustic measurement of the melt in the extrusion die. Further work is proposed to normalize for the effect of variations in the melt temperature and pressure on the ultrasound measurements. DOI : 10.3139/217.1614 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16145
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible In-process rheometry studies of LDPE compounds / A. L. Kelly in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : In-process rheometry studies of LDPE compounds : Part I : Unfilled resin Type de document : texte imprimé Auteurs : A. L. Kelly, Auteur ; M. Woodhead, Auteur ; D. Barnwell, Auteur ; K. Martin, Auteur ; P. D. Coates, Auteur Année de publication : 2000 Article en page(s) : p. 355-360 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : The initial part of a comprehensive study into the investigation and validation of in-process measurements on a low density polyethylene (LDPE) compound during extrusion is reported. An unfilled, commercial grade of low density polyethylene was processed using fully instrumented, computer monitored, single and twin screw extruders in the Interdisciplinary Research Centre (IRC) laboratories, University of Bradford. Three in-process rheometers were used; a prototype Rosand capillary on-line rheometer (OLR), a four sensor slit die in-line rheometer (ILR) and a six sensor slit die ILR. Off-line comparisons were carried out using a Rosand RH7 twin bore capillary rheometer. All devices allowed shear flow characterisation at a range of processing rates, and the capillary rheometers also provided a measurement of entry pressure drop through the use of orifice dies. The six-sensor ILR also allowed measurement of entry pressure drop into the slit, although the differences in flow geometry meant these measurements were not directly comparable with the capillary devices, and exit pressures were extrapolated from ILR pressure drops. The in-process devices exhibited very good agreement with measurements made off-line, in both shear flow and entry pressures. In-line slit die measurements were very close to those made using capillary dies, despite the in-line tests being non-isothermal and employing a different geometry of measurement section. Differences in melt rheology between single and twin extrusion were observed, due to the amount of mechanical work input by each extruder. Overall, good agreement was observed from the four different routes to measurement, for the LDPE examined. DOI : 10.3139/217.1612 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16146
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible In-process rheometry studies of LDPE compounds / A. L. Kelly in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : In-process rheometry studies of LDPE compounds : Part II : Magnesium hydroxide filled Type de document : texte imprimé Auteurs : A. L. Kelly, Auteur ; M. Woodhead, Auteur ; P. D. Coates, Auteur ; D. Barnwell, Auteur ; K. Martin, Auteur Année de publication : 2000 Article en page(s) : p. 361-368 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Screw extrusion/Mixing - The second part of a comprehensive study into the investigation and validation of in-process measurements on a low density polyethylene compound during extrusion is reported. A commercial grade of branched low density polyethylene was used in the study, compounded with various levels of magnesium hydroxide flame retardant filler, up to 50% by weight. In-line and on-line rheometry were used to monitor melt flow behaviour during single screw and twin screw extrusion; off-line capillary rheometry was performed on the compound before and after extrusion, to examine any change in rheology. Morphological observations were made using scanning electron microscopy, and molecular characterisations carried out using gel permeation chromatography. In-process rheometry was found to be able to detect the presence of filler at low and high loadings, but was unable to discriminate between intermediate levels. Off-line rheometry indicated that twin screw extrusion altered the rheology of the compound, and capillary wall slip was found to increase after extrusion. Morphological observation indicated that filler in the compound was better dispersed after extrusion, especially at high volume fractions. Molecular weight and polydispersity of the LDPE were shown to increase after extrusion, more so in the case of low filler loadings. Overall, in-process measurements provided useful rheological data, and the compound was found to exhibit complex, process-dependent rheology. DOI : 10.3139/217.1613 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16154
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible Rheological and morphological properties of immiscible blends and microfiber preparation from the blends / W. S. Lyoo in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : Rheological and morphological properties of immiscible blends and microfiber preparation from the blends Type de document : texte imprimé Auteurs : W. S. Lyoo, Auteur ; Y. G. Choi, Auteur ; J. H. Choi, Auteur ; W. S. Ha, Auteur ; B. C. Kim, Auteur Année de publication : 2000 Article en page(s) : p. 369-379 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Screw extrusion/Mixing - One modified poly(ethylene terephthalate) (m-PET) containing 16 mol % of isophthalic acid content and three kinds of isotactic polypropylene (i-PP) with different molecular weights were melt blended in various volume ratios by a twin screw extruder. The dynamic viscosity of the i-PP/m-PET blend showed positive deviation at lower volume content of i-PP and negative deviation at higher volume content of i-PP. The size of dispersed phase increased with an increase of the minor component. Also, the less difference between the viscosities of two polymers caused the smaller particle size in the blend and the smaller critical Weber number. After melt spinning of these binary polymer blends, m-PET and i-PP micro staple fiber, whose diameter was about 0.13 to 2.75 µm, could be obtained by extracting the continuous phase with a proper solvent. The less the minor component in the blend, the better the spinnability of the blended polymers and the physical properties of the fiber. Also, when i-PP was the continuous phase, the spinnability and the physical properties of the fibers were better than the opposite case. Molecular weight of i-PP and the blend ratio had a marked influence on the diameter of microfibers. The micro fiber obtained from i-PP which has similar viscosity with m-PET showed the smallest diameter than those obtained from other two i-PPs. Note de contenu : - EXPERIMENTAL : Materials - Preparation of blend - Melt spinning of blend - Microfiber formation- Characterization of product
- RESULTS AND DISCUSSION : Rheological properties of the blend - Dependence of phase size on the blend composition - Melt spinning of the blendDOI : 10.3139/217.1610 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16155
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible Development of a direct polycondensation process for poly (L-lactic acid) / T. Fukushima in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : Development of a direct polycondensation process for poly (L-lactic acid) Type de document : texte imprimé Auteurs : T. Fukushima, Auteur ; Y. Sumihiro, Auteur ; K. Koyanagi, Auteur ; N. Hashimoto, Auteur ; Y. Kimura, Auteur ; T. Sakai, Auteur Année de publication : 2000 Article en page(s) : p. 380-385 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Reactive extrusion - Poly(L-lactic acid) (PLLA) is quite promising for use as biodegradable and non-petroleum derived plastics. In this study we developed an innovative two-step polycondensation process so as to produce economically PLLA with high molecular weight. The process is composed of both melt polycondensation under the lactide-reflux and solid-phase polycondensation. First we studied a direct polycondensation of L-lactic acid with a small amount of solvent, using a mixture of L-lactic acid as raw material, diphenyl ether as solvent, Tin (II) chloride dihydrate as catalyst, and p-toluene sulfonic acid as a discoloration prevention agent. After the dehydrative oligomerization of L-lactic acid, the polycondensation of the oligocondensates and solid-phase post-polycondensation, PLLA of Mw=266,000 could be obtained. Then, we carried out direct bulk polycondensation tests from L-lactic acid without any solvent added. After optimization of the reaction conditions, PLLA with Mw=134,000 was successfully produced by the melt-polycondensation of L-lactic acid accompanied by solid-phase post-poly-condensation. In both systems, the lactide-reflux was indispensable for promoting dehydration/water removal. The refluent lactide was taken into the polymer-chain by trans-esterification reaction during the melt-polycondesation. Furthermore, the catalyst was allowed to deactivate and stabilize during the solid-phase polymerization to cause the Mw growth. Note de contenu : - EXPERIMENTAL : Reagents - Polymerization - Analyses - Two-step polycondensation process from melt to solid phase - Polycondensation process without solvent
- RESULTS AND DISCUSSIONS : Polycondensation using with a batch-type reactor - Additive effects on the melt and solid-phase polycondensation - Bulk polycondensation process without solvent on laboratory-scale - A proposal for a direct molding systemDOI : 10.3139/217.1615 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16156
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible Radially dependent stress and modeling of solidification in filament melt spinning / G. M. Henson in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : Radially dependent stress and modeling of solidification in filament melt spinning Type de document : texte imprimé Auteurs : G. M. Henson, Auteur ; G. E. Bechtel, Auteur Année de publication : 2000 Article en page(s) : p. 386-397 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Fibers and films - When polymer fibers are manufactured by melt spinning, axial velocity is nearly uniform across any cross section but temperature and stress vary significantly across the fiber radius. Thus, the fiber solidifies from the outside in, with the fiber being solid on the outside but molten on the inside for some distance before complete solidification, and stress near solidification, the controller of mechanical properties of the spun fiber, has radial variation. We present a computationally 1D melt spinning model which recognizes the radially inhomogeneous solidification region, and computes axial and radial dependence of stress in the spinline. With this radial resolution, stress near solidification is now the stress evaluated on a surface near the solidification boundary. In simulations of melt spinning processes, we investigate features of the solidification boundary and stress near solidification, and examine how these change as material properties and process conditions change. As part of this study, we propose and investigate a solidification criterion that is a function of both stress and temperature. Note de contenu : - Model for the molten part of the spinline
- Model for the solidified part of the spinline
- Transition between the molten and solid models
- The 3D stress field near solidification
- Stress distribution as a function of process conditions and material
- Stress dependent solidificationDOI : 10.3139/217.1611 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16157
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible Structure development in melt spinning syndiotactic polypropylene and comparison to isotactic polypropylene / D. Choi in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : Structure development in melt spinning syndiotactic polypropylene and comparison to isotactic polypropylene Type de document : texte imprimé Auteurs : D. Choi, Auteur ; J. L. White, Auteur Année de publication : 2000 Article en page(s) : p. 398-405 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Fibers and films - A basic investigation of the development of crystallization and orientation during the melt spinning of syndiotactic and isotactic polypropylene is described. Both polymers were melt spun through ambient air or into ice water at various draw-down ratios and melt temperatures. The melt spun filaments were characterized by wide angle x-ray diffraction (WAXD), birefringence and differential scanning calorimetry (DSC). The polymorphic behavior of isotactic polypropylene during melt spinning is well known. The filaments melt spun through ambient air exhibit the monoclinic α-form while the filaments melt spun into ice water form a smectic structure at low draw-down ratios. Syndiotactic polypropylene also exhibited polymorphic behavior during melt spinning. Disordered Form I with (t2g2)2 helices was found at low spinline stresses and Form III with all trans chain conformation was found at high spinline stresses. The criterion of the spinline stress for this transition was found to be about 6–9 MPa for all samples of various molecular weights, melt temperatures and cooling rates. Syndiotactic polypropylene crystallized much more slowly than isotactic polypropylene and did not exhibit a smectic mesomorphism under ice-water quenched conditions. The melt spun filaments of syndiotactic polypropylene exhibited lower birefringences and amorphous orientations but higher crystalline orientations than those of isotactic polypropylene, compared at the same spinline stresses. Note de contenu : - EXPERIMENTAL : Materials - Material characterization - Melt spinning - Fiber characterization
- RESULTS : Spinline stresses - DSC scans - WAXD patterns - Crystalline orientation - Birefringence
- DISCUSSION : Polymorphism - Crystallization rate in melt spinning - Orientation and birefringenceDOI : 10.3139/217.1608 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16158
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible Investigation of structure and properties in biaxially stretched poly(butylene terephthalate) films / K.-J. Song in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : Investigation of structure and properties in biaxially stretched poly(butylene terephthalate) films Type de document : texte imprimé Auteurs : K.-J. Song, Auteur ; J. L. White, Auteur Année de publication : 2000 Article en page(s) : p. 406-415 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Fibers and films - Effects of deformation history on the development of structure and properties in biaxially stretched poly(butylene terephthalate) (PBT) films are described. PBT cast films are stretched at two temperatures: 65°C and 90°C, with varying draw ratios. The refractometer and X-ray scattering techniques characterize the resultant films. As-stretched films have crystals of small sizes, in which the α crystals are appreciably larger and oriented more than the β phase. Films that are stretched at the low temperature, on the other hand, exhibit higher orientations of both the overall and amorphous chains. Annealing of the films under constraint causes the crystalline phase to undergo perfection and transition. A model of crystalline morphology is presented which describes the mechanical anisotropy present in biaxially oriented PBT films. Note de contenu : - EXPERIMENTAL : Materials and film formation - Wide angle X-ray diffraction - Refractive index - Tensile test
- RESULTS : WAS flat film photographs - WAXS diffractometer scans - WAXS pole figures - SAXS scattering patterns - Refractive indices - Mechanical properties
- DISCUSSION : Crystal character - Crystalline orientation - Amorphous orientation - Crystalline morphology - Mechanical behaviorDOI : 10.3139/217.1609 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16159
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Code-barres Cote Support Localisation Section Disponibilité 001014 - Périodique Bibliothèque principale Documentaires Disponible Filling and postfilling analysis of injection/compression molding / W.-B. Young in INTERNATIONAL POLYMER PROCESSING, Vol. XV, N° 4 (12/2000)
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Titre : Filling and postfilling analysis of injection/compression molding Type de document : texte imprimé Auteurs : W.-B. Young, Auteur Année de publication : 2000 Article en page(s) : p. 416-422 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Injection compression molding is a process that modifies the original injection molding process to have a compression stage after the injection. This process is suitable for precision injection molding parts. The success of an injection compression molding process relies on proper design of the mold and selection of process conditions. The main scope of this study is to develop a process simulation tool for the injection compression molding process. The simulation tool is used to predict the state variations of the material during the molding, including molding flow, distributions of temperature and pressure, and the material shrinkage. The effect of the compression action on the molding part was investigated by this study. The compression action can provide more uniform packing on the mold cavity. But, with the non-uniform cooling, material can have different fluidity in the cavity, which induces pressure gradients during the compression action. From the simulation results, it is demonstrated that a two-stage compression action in the injection compression molding process can reduce the pressure gradient in the cavity and still have low shrinkage. By using this method, products with higher precision and lower warpage can be molded. DOI : 10.3139/217.1618 Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=16160
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