Development of a novel transcription molding process to fabricate sophisticated polymer products with precise microstructure and high transparency applicable to display devices and bio-chips / Hiroshi Ito in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 2 (05/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 2 (05/2007) . - p. 155-165 Titre : Development of a novel transcription molding process to fabricate sophisticated polymer products with precise microstructure and high transparency applicable to display devices and bio-chips Type de document : texte imprimé Auteurs : Hiroshi Ito, Auteur ; K. Yakemoto, Auteur ; T. Saito, Auteur ; I. Satoh, Auteur Année de publication : 2007 Article en page(s) : p. 155-165 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : In this study, we developed a novel transcription-molding process and experimentally discussed its validity for fabricating polymer products having the precise microstructure on the surface. The process was named "Melt-Transcription Process" which consists of two characteristic stages ; coating and compression. In the coating stage, a molten polymer is coated on the surface of a metal mold having the precise microstructure by a coating device specially designed in this study. The thickness of the coated polymer melt is typically 100µm or more. Immediately after coating, the coated polymer is compressed against the mold surface so as to make the polymer flow into the microstructure cavities engraved on the mold, and to fabricate the 3-dimensional structure of polymer products. The pressure required for compression is quite lower than that in conventional nano-imprinting process, because the molten polymer of high temperature is distributed in advance over the mold surface in the coating stage. The "Melt-Transcription Process" was applied to fabricate polymer products with the size of 150mm in length, 150mm in width and 1mm in thickness, having the microstructure of tens micrometers on their surface. Cyclo-olefin polymer (COP) and Polymethyl methacrylate (PMMA) were used as the polymer materials, and the dimensions and transcription ratios (the ratio of the height of the transcribed microstructure to the depth of the microstructure on the mold) of the molded microstructure were experimentally evaluated. As a result, by the Melt-Transcription Process, the microstructure was sufficiently transcribed on a very thin substrate of large surface area with high transcription ratios, typically 95 % or more, under relatively low compression pressure of less than 10MPa. DOI : 10.3139/217.0984 En ligne : https://drive.google.com/file/d/1orbulG_RMYHtEVlbGXprOlFzAwNo8AHB/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2755 [article]

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The effects of processing parameters on the residual wall thickness distribution at the sharp angle corner of water assisted injection molded parts / T. Pudpong in INTERNATIONAL POLYMER PROCESSING, Vol. XXVIII, N° 5 (11/2013)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVIII, N° 5 (11/2013) . - p. 528-540 Titre : The effects of processing parameters on the residual wall thickness distribution at the sharp angle corner of water assisted injection molded parts Type de document : texte imprimé Auteurs : T. Pudpong, Auteur ; P. Buahom, Auteur ; I. Satoh, Auteur ; T. Saito, Auteur Année de publication : 2013 Article en page(s) : p. 528-540 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Epaisseur -- Mesure Matières plastiques -- Moulage par injection Matières plastiques -- Moulage par injection assistée par eau Polypropylène Simulation par ordinateur Tubes Index. décimale : 668.4 Plastiques, vinyles Résumé : Water-assisted injection molding (WAIM) has been widely used for tubular plastic parts due to its advantages of relatively low cost and fast cycling time. However, the non-uniform distribution of the wall thickness, especially at the sharp corner, is still a basic problem in the WAIM process. This work presents the effects of sharp corner angles on wall thickness distribution in sections near corners for various processing conditions of the WAIM process, including melt temperature, mold temperature, water delay time, water holding time, and holding pressure. Three grades of polypropylene (PP) resins with different melt flow indices were studied using seven mold geometries that varied the angle of the sharp corner section. The wall thickness distribution at the corner sections were characterized in terms of inner and outer residual wall thicknesses, hollow core ratio, and the percentage of difference between the inner and outer wall thicknesses. In addition, computational fluid dynamic simulations with Moldflow Plastics Insight version 4.1 were performed for each sharp corner angle. It was found that the wall thickness distribution of the straight tube was more uniform than those of the curve tubes. Water injection delay time and water pressure were the major parameters that had a significant impact on the hollowed core ratios, while the percent difference between inner and outer wall thicknesses was mainly influenced by melt temperature. Note de contenu : - EXPERIMENTAL PROCEDURE : Materials - Injection molding machine and mold - Process parameters - Characterization - Simulation - RESULTS AND DISCUSSION : Relationship between shear rate and inner residual wall thickness - Effect of MFI on residual wall thickness distribution - Effect of melt temperatures on residual wall thickness distribution - Effect of mold temperature on residual wall thickness distribution - The effect of water delay time on residual wall thickness distribution - The effect of water pressure on residual wall thickness distribution - The effect of water holding time on residual wall thickness distribution - Stifness - Inner surface roughness - Switchover mark - Microscopic observation DOI : 10.3139/217.2792 En ligne : https://drive.google.com/file/d/1fjKjyjWOGlo3-G8uXFzpKHhITn1nsyA2/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=19899 [article]

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