Effect of molding history on molecular orientation relaxation during physical aging of polystyrene injection moldings / Kousaku Tao in INTERNATIONAL POLYMER PROCESSING, Vol. 38, N° 2 (2023)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 38, N° 2 (2023) . - p. 233-243 Titre : Effect of molding history on molecular orientation relaxation during physical aging of polystyrene injection moldings Type de document : texte imprimé Auteurs : Kousaku Tao, Auteur ; Koji Yamada, Auteur ; Seiji Higashi, Auteur ; Keitaro Kago, Auteur ; Shiho Kuwashiro, Auteur ; Hiroshi Hirano, Auteur ; Hiroki Takeshita, Auteur ; Katsuhisa Tokumitsu, Auteur Année de publication : 2023 Article en page(s) : p. 233-243 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Détérioration Matières plastiques -- Moulage par injection Orientation moléculaire (matériaux) Phénomènes de relaxation (matériaux) Polystyrène Index. décimale : 668.4 Plastiques, vinyles Résumé : This work examined the effect of changing molding conditions on the physical aging of polystyrene injection moldings. First, we investigated the relationship between the molecular orientation and the molding conditions. The molecular orientation near the surface changed with changing injection rate, so we hypothesized that this molecular orientation might form during the filling stage. Because this molecular orientation did not relax under heat treatment below the glass transition temperature (Tg), the oriented molecules near the surface were thought to be elongated owing to the high strain rate during the filling stage. On the other hand, the molecular orientation in the core layer changed with changing holding pressure and relaxed under heat treatment below Tg. Thus, the molecules in the core layer might become oriented during the holding stage and not be elongated owing to the slow strain rate. Furthermore, the molecular orientation in the core layer decreased with increasing mold temperature, and the physical heat resistance improved with increasing mold temperature. Meanwhile, the excess enthalpy did not change with changing molding conditions. Therefore, the improvement in physical heat resistance with increasing mold temperature was likely caused by the decrease in the molecular orientation in the core layer. Analyzing the relaxation behavior of the molecular orientation suggested that increasing mold temperature reduced the number of oriented molecules with large deformation in the core layer. Note de contenu : - EXPERIMENTAL PROCEDURE : Material - Injection molding - Heat treatment - Evaluation of molecular orientation by laser Raman spectroscopy - Raman mapping of cross sections - Comparison of enthalpy relaxation behaviors - Determination of heat distortion temperature - RESULTS AND DISCUSSION : Effect of molding conditions on molecular orientation - Effect of molding conditions on enthalpy relaxation - Effect of molding conditions on physical heat resistance - Effect of mold temperature on the structure of oriented molecules DOI : https://doi.org/10.1515/ipp-2022-4264 En ligne : https://drive.google.com/file/d/1RkYjnHka-5hUU9fMmnn3Qb1HmaDdJfpG/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=39504 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
24121	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Effect of uniaxial stretching on molecular orientation, crystallinity and oxygen permeability of ethylene vinyl alcohol / L. Wang in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 3 (2021)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 36, N° 3 (2021) . - p. 314-321 Titre : Effect of uniaxial stretching on molecular orientation, crystallinity and oxygen permeability of ethylene vinyl alcohol Type de document : texte imprimé Auteurs : L. Wang, Auteur ; E. Jalali Dil, Auteur ; Abdellah Ajji, Auteur Année de publication : 2021 Article en page(s) : p. 314-321 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse thermique Copolymère éthylène alcool de vinyle C'est aujourd'hui le matériau le plus utilisé dans l'emballage rigide alimentaire. Il peut être utilisé avec des matériaux de structure comme le polyéthylène, polypropylène ou polystyrène. Ce copolymère présente une excellente imperméabilité à l'oxygène, au gaz carbonique et aux arômes, à condition de protéger de l'influence de l'humidité qui fait chuter fortement ses performances. Pour palier cet inconvénient, il est souvent pris en sandwich dans des structures multicouches à base de polyoléfines PE ou PP peu sensibles à l'humidité. Il est utilisé pour les emballages de compotes, jus de fruits, fromages, sauces, crèmes et yaourts, mayonnaise, sauce tomate... Diffraction des rayons X à grand angle Etirement (mécanique) Films plastiques Orientation moléculaire (matériaux) Oxygène Perméabilité Structures multicouches Index. décimale : 668.4 Plastiques, vinyles Résumé : This work studies the effects of uniaxial stretching on molecular orientation, crystallinity, crystallography and oxygen permeability of high barrier multilayer films based on EVOH barrier layer. Film samples were prepared using two different blow-up ratios (BUR) of 1 and 3. Uniaxial stretching was applied at 100°C using a tensile machine equipped with an environmental chamber. Fourier transform infrared (FTIR) spectroscopy was used to examine the molecular orientation in the EVOH layer before and after stretching and confirmed a considerable increase in the molecular orientation in the EVOH layer. Dynamic scanning calorimetry (DSC) and wide-angle X-ray diffraction (XRD) results point to the perfection of EVOH crystal structure by applying uniaxial stretching at high temperatures. Oxygen permeability results showed a considerable 25% decrease after stretching of the sample with lower BUR while a significant 80% reduction in oxygen permeability was observed for the sample prepared at higher BUR. The mechanism involved in increasing oxygen permeability due to the uniaxial stretching at high temperature is discussed in detail. Note de contenu : EXPERIMENTAL : Materials - Film and sheet preparation - Uniaxial stretching - Scanning electron microscopy (sem) - Oxygen transmission - Differential scanning calorimetry (DSC) - Wide angle X-ray diffraction (WAXD) - Orientation index RESULTS AND DISCUSSION : Effect of stretching on layer thicknesses in the multilayer films - Effect of uniaxial stretching on molecular orientation - Effect of stretching on EVOH crystallinity and crystallography - Effect of uniaxial stretching on oxygen permeability of EVOH - Table 1 : Thickness of the layers in multilayer film samples measured from SEM image analysis - Table 2 : Calculated orientation indices of the film samples - Table 3 : Summary of DSC results for film samples before and after stretching DOI : https://doi.org/10.1515/ipp-2020-4062 En ligne : https://drive.google.com/file/d/1aV48yWOxkqVWcsGUygndhOcYux8ywd9r/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=36373 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
23733	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Influence of the mold temperature and part thickness on the replication quality and molecular orientation in compression injection molding of polystyrene / Benedikt Roth in INTERNATIONAL POLYMER PROCESSING, Vol. XXXIV, N° 4 (08/2019)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXIV, N° 4 (08/2019) . - p. 425-433 Titre : Influence of the mold temperature and part thickness on the replication quality and molecular orientation in compression injection molding of polystyrene Type de document : texte imprimé Auteurs : Benedikt Roth, Auteur ; M.-Y. Zhou, Auteur ; Dietmar Drummer , Auteur Année de publication : 2019 Article en page(s) : p. 425-433 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Moulage par compression Moulage par injection-compression Orientation moléculaire (matériaux) Polystyrène Température -- Contrôle Index. décimale : 668.4 Plastiques, vinyles Résumé : It is well known that the process of injection molding with dynamic mold temperature control leads to a good replication quality of high aspect ratio microstructures. However, the inhomogeneous pressure distribution during the holding pressure phase results in an anisotropy of the component properties, low dimensional accuracy and, especially with optical polymers, in undesired stress birefringence. The anisotropy is based on the orientation of the molecular chains in the flow direction, which can be reduced by an injection-compression molding (ICM) process. In order to use the synergy from both processes, an injection-compression molding process with dynamic mold temperature control can be utilized. Within the scope of this investigation, the new process was reproduced by an ICM process at elevated mold temperature (ICM_EMT) and compared with injection molding (IM) with regard to molding accuracy and optical properties in dependence of component thickness and mold temperature. In order to evaluate the molding accuracy, the roughness of a wire-eroded microstructure on the cavity surface was measured. To determine the degree of orientation, the optical properties considered were the transmission and the path difference. It was shown that the adapted ICM process was able to achieve a high degree of replication accuracy with a low degree of orientation, especially for thin-walled components. ICM at elevated mold temperature reduced the path difference in the components with the lowest wall thickness by a factor of two while at the same time optimizing the replication of the microstructure. This could also be confirmed by transmission measurements. DOI : 10.3139/217.3802 En ligne : https://drive.google.com/file/d/1bMeibb5sQxYzP7WmZRsktl2UWvG7FUtN/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=33061 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
21083	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Molecular orientation behavior of isotactic polypropylene films under uniaxial and biaxial deformation at elevated temperatures / S. Yoshida in INTERNATIONAL POLYMER PROCESSING, Vol. XXVII, N° 2 (05/2012)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVII, N° 2 (05/2012) . - p. 237-244 Titre : Molecular orientation behavior of isotactic polypropylene films under uniaxial and biaxial deformation at elevated temperatures Type de document : texte imprimé Auteurs : S. Yoshida, Auteur ; T. Sawada, Auteur ; T. Kawamura, Auteur ; K. Nitta, Auteur Année de publication : 2012 Article en page(s) : p. 237-244 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Contraintes (mécanique) Déformations (mécanique) Films plastiques Matériaux -- Déformations géométriques et dimensionnelles Orientation moléculaire (matériaux) Polymères -- Effets des hautes températures Polypropylène Index. décimale : 668.9 Polymères Résumé : In-situ molecular orientation behavior of isotactic polypropylene films prepared by quenching at 0 ºC was investigated under uniaxial and biaxial extension at elevated temperatures. Both the retardation value of film and the stress were simultaneously measured during stretching. The stress required to deform films depended on the stretching temperature, but the retardation was nearly independent of temperature. DOI : 10.3139/217.2527 En ligne : https://drive.google.com/file/d/1p9NXvcVfdamjwve1G-31kkZxUwPd9Pxv/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=14693 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
13846	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Paint/polymer interface structure for ABS injection moldings / Y. Aoki in INTERNATIONAL POLYMER PROCESSING, Vol. XXVI, N° 4 (09/2011)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVI, N° 4 (09/2011) . - p. 399-402 Titre : Paint/polymer interface structure for ABS injection moldings Type de document : texte imprimé Auteurs : Y. Aoki, Auteur ; M. Aita, Auteur ; Y. Mizuochi, Auteur ; T. Kinumura, Auteur ; M. Sugimoto, Auteur ; J. Takimoto, Auteur ; K. Koyama, Auteur ; H. Kiritani, Auteur ; M. Oomori, Auteur ; A. Hirashima, Auteur Année de publication : 2011 Article en page(s) : p. 399-402 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Contraintes résiduelles Interfaces solide-liquide Matières plastiques -- Moulage par compression Matières plastiques -- Moulage par injection Matières plastiques -- Revêtement:Matières plastiques -- Peinture Orientation moléculaire (matériaux) Terpolymère acrylonitrile butadiène styrène Index. décimale : 668.9 Polymères Résumé : Structure of paint/polymer interface was investigated for the injection molded and compression molded ABS specimens. For the interface of the injection molded specimen, a peculiar “zigzag” structure formation of several tens µm in size was observed. In contrast, the interface structure was not observed for the compression molded specimen and injection molded specimen annealed above the glass transition temperature (Tg). These facts indicate that the interface structure is related to the residual stress and molecular orientation at the surface of the injection molding specimen, because both surface structures would be removed by annealing at temperatures above Tg. The interface structure was strongly dependent on the curing agent concentration. The depth of the structure decreased with increasing curing agent concentration because of decreasing in curing time. At painting temperature between 70 °C and 130 °C, the depth and pitch were constant. However, below 60 °C and above 140 °C, the depth and pitch were changed. These results strongly suggest that the interface structure is attributable to relaxation of the surface residual stress and molecular orientation by paint soaking. DOI : 10.3139/217.2433 En ligne : https://drive.google.com/file/d/1NMLtPwxOnp-pwA_kF5oNn2KXKMOCMQUz/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12441 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
013208	-	Périodique	Bibliothèque principale	Documentaires	Disponible

Preparation and photo-oxidation aging behavior of oriented polylactic acid / Z.-Q. Li in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 4 (2021)  

Permalink

Relationship between molecular orientation relaxation during physical aging and heat resistance of polystyrene injection moldings / K. Tao in INTERNATIONAL POLYMER PROCESSING, Vol. 36, N° 5 (2021)  

Permalink

---

1 (1 - 7 / 7)