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

Study on permeability of porous ultra-high molecular weight polyethylene (UHMWPE) / B.-Y. Jiang in INTERNATIONAL POLYMER PROCESSING, Vol. XXXII, N° 2 (05/2017)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXXII, N° 2 (05/2017) . - p. 159-164 Titre : Study on permeability of porous ultra-high molecular weight polyethylene (UHMWPE) Type de document : texte imprimé Auteurs : B.-Y. Jiang, Auteur ; M.-Y. Zhou, Auteur ; Can Weng, Auteur ; C.-F. Li, Auteur Année de publication : 2017 Article en page(s) : p. 159-164 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Analyse thermique Essais dynamiques Frittage Le frittage est un procédé de fabrication de pièces consistant à chauffer une poudre sans la mener jusqu’à la fusion. Sous l'effet de la chaleur, les grains se soudent entre eux, ce qui forme la cohésion de la pièce. Matériaux poreux Perméabilité Polyéthylène à ultra haut poids moléculaire Polymères -- Propriétés mécaniques Index. décimale : 668.4 Plastiques, vinyles Résumé : In recent years, porous materials are gaining in popularity for engineering applications, due to their special characteristics, such as low density, large specific surface area, and excellent permeability. In this study, powder processing technique was used to prepare ultra-high molecular weight polyethylene UHMWPE porous materials. Sintering temperature was obtained by combining differential scanning calorimetry (DSC) analysis and tensile tests. The surface morphology of sintering necks and tensile fracture were observed by scanning electron microscopy (SEM). Finally, single factor tests and orthogonal experiments were conducted to optimize three main processing parameters for a better permeability. It is found that the proper sintering temperature range would be from 143 to 153.1°C. According to the significance of influence, processing factors come in the sequence of the particle size, the compaction strength and the sintering temperature. Porous materials were successfully prepared, under the optimized parameters as the particle size >250 ?m, the compaction strength of 2.5 MPa and the sintering temperature of 152°C. Note de contenu : - DETERMINATION OF SINTERING TEMPERATURE RANGE : Sinter material - Thermal analysis - Preparation of porous UHMWPE material - Tensile strenght - EXPERIMENTS : Microstructures of UHMWPE porous material - Calculation of permeability - Single factor tests ans orthogonal tests - RESULTS AND DISCUSSION : Effects of processing parameters on permeability - Optimization of processing parameters DOI : 10.3139/217.3189 En ligne : https://drive.google.com/file/d/12WC98I6-a_6__miHLY5WU9GWRj9t9L0E/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=28491 [article]

Réservation

Réserver ce document

Exemplaires (1)

Code-barres	Cote	Support	Localisation	Section	Disponibilité
18872	-	Périodique	Bibliothèque principale	Documentaires	Disponible

---

1 (1 - 2 / 2)