Dynamic mold surface temperature control using induction and heater heating combined with coolant cooling / S. C. Chen in INTERNATIONAL POLYMER PROCESSING, Vol. XXI, N° 5 (11/2006)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXI, N° 5 (11/2006) . - p. 457-463 Titre : Dynamic mold surface temperature control using induction and heater heating combined with coolant cooling Type de document : texte imprimé Auteurs : S. C. Chen, Auteur ; Y. J. Chang, Auteur ; J. A. Chang, Auteur ; W. R. Jong, Auteur Année de publication : 2006 Article en page(s) : p. 457-463 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : In this study, both electrical heater heating and electromagnetic induction heating combined with coolant cooling are developed to achieve a dynamic mold surface temperature control. Simulation tool was also developed by integration of both thermal and electromagnetic analysis modules of ANSYS. The capability and accuracy of simulations on the heater heating and induction heating were verified with experiments. To evaluate the feasibility and efficiency of heater heating and induction heating on the mold surface temperature control, a mold plate, roughly about an inset size of cellular phone housing, installed with five heaters and designed with four cooling channel with coolant running through, was utilized for the demo experiments varying mold surface temperature between 110 °C and 200 °C. During induction heating/cooling case, it takes 4 s to increase mold surface temperature from 110 to 200 °C and it takes another 21 s for mold surface to cool down to 110 °C. The mold plate surface temperature can be raised at about 22.5 °C/s and cooled down at 4.3 °C/s within the mentioned temperature range. Mold plate temperature distribution exhibits good uniformity as well in all stage of heating/cooling process. For heaters heating, it takes 37 s to increase mold surface temperature from 110 to 200 °C and it takes another 30 s for mold surface to cool down to 110 °C. The temperature rising rate is only about 2.4 °C/s. Induction heating is more efficient in mold surface temperatures control than electrical heating and it does eliminate the weld line mark when applied to a tensile test mold with double gate design prior to melt injection. DOI : https://doi.org/10.3139/217.0992 En ligne : https://drive.google.com/file/d/1POJJN3c7Uhrbw4E0wXqSuzlojbwPdYQA/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2799 [article]

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Establishment of gas counter pressure technology and its application to improve the surface quality of microcellular injection molded parts / S. C. Chen in INTERNATIONAL POLYMER PROCESSING, Vol. XXVI, N° 3 (07/2011)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVI, N° 3 (07/2011) . - p. 275-282 Titre : Establishment of gas counter pressure technology and its application to improve the surface quality of microcellular injection molded parts Type de document : texte imprimé Auteurs : S. C. Chen, Auteur ; P. S. Hsu, Auteur ; Y. W. Lin, Auteur Année de publication : 2011 Article en page(s) : p. 275-282 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Moulage par injection microcellulaire Mousses plastiques Polystyrène Tags : 'Contre-pression  gaz'  GCP  'Moulage  injection  microcellulaire'  'Mousse  polystyrène' Index. décimale : 668.4 Plastiques, vinyles Résumé : The purpose of this study is to establish the Gas Counter Pressure (GCP) technology in combined with microcellular injection molding process. The application of gas into the mold cavity during the melt injection period provides a counter force against the melt front advancement, restricting the foaming process during the melt filling stage. Various gas counter pressures from 0 bar up to 300 bar and gas holding times of 0 to 10 s after filling completion were employed for investigating their relevant effect. It was found that when gas counter pressure is greater than 100 bar, foaming does not appear in the skin layer if no holding time is applied after melt-filling. As gas counter pressure increases, thickness of the solid skin layer without foaming also increases. Employment of holding time after melt-filling also assists foaming restriction in the melt core area. If a holding time of 10 s is applied combined with a counter pressure greater than 100 bar, foaming is completely restricted resulting in a transparent PS sample part. The part surface of those subjected to foaming-restriction in the skin layer also appears to be smooth and glossy. For the black PS parts molded via microcellular injection combined with gas counter pressure, it appears the same gloss quality as that achieved by conventional injection molding. DOI : 10.3139/217.2437 En ligne : https://drive.google.com/file/d/1n3HgCjklMlvMNw-m-OWePLgATkWTSzfG/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=12406 [article]

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Reduction of DNA damage by nicotinamide after reactive oxygen species treatment / S. C. Chen in IFSCC MAGAZINE, Vol. 5, N° 1 (01-02-03/2002)

[article]  inIFSCC MAGAZINE > Vol. 5, N° 1 (01-02-03/2002) . - p. 3-6 Titre : Reduction of DNA damage by nicotinamide after reactive oxygen species treatment Type de document : texte imprimé Auteurs : S. C. Chen, Auteur ; Y. Takasli, Auteur ; Y.-C. Chen, Auteur ; T. H. Tsai, Auteur ; C. H. Hu, Auteur ; W. R. Lee, Auteur Année de publication : 2002 Article en page(s) : p. 3-6 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : ADN -- Réparation Apoptose Nicotinamide Peroxyde d'hydrogène Le peroxyde d'hydrogène (H2O2), communément appelé eau oxygénée ou encore perhydrol (appellation industrielle), est un composé chimique liquide et visqueux, aux puissantes propriétés oxydantes (il est aussi réducteur). C'est donc un agent blanchissant efficace qui sert de désinfectant et (à haute concentration) d'oxydant ou monergol dans les fusées spatiales. Rayonnement ultraviolet Tags : Nicotinamide  'Ultraviolet  C'  (UVC)  'OPeroxyde  d'hydrogène'  (ROS)'  'Dommage  de  l'ADN''  Apoptose  '8-hydroxy-2'-deoxyguanosine(8-OhdG)' Index. décimale : 668.5 Parfums et cosmétiques Résumé : We investigated whether nicotinamide acts as a preventive agent of apoptosis induced by H2O2 and UVC irradiation in skin cells including keratinocyte HaCat and NIH3T3 cells. In this study, both H2O2 (450μM) and UVC (40J/m2) irradiation-induced cell death were detected by MTT assay, and nicotinamide showed the dose dependent inhibition on H2O2 and UVC induced cell death. Morphological study by microscopic observation showed that H2O2 or UVC induced cellular morphological changes including appearence of rounded cells or swelling cells, characteristic og apoptosis. In the presence of nicotinamide, H2O2 and UVC induced morphological changes were attenuated significantly. Prevention of cells from H2O2 and UVC induced cell death was asociated with decrease of apoptotic bodies by flow cytometry analysis and attenuation of the appearance of DNA ladders by DNA electrophoresis. Induction of p53 protein was detected in H2O2-treated NIH3T3 cells and nicotinamide suppressed its increase. However, bcl-2, bax and α-tubulin proteins were remained unchanged. ROS have been demonstrated to be involved in the H2O2 and UVC induced apoptosis. In this study, H2O2 or UVC irradiation increase intracellular peroxide levels detected by DCHF-DA assay and fluorescent microscopic observation, and nicotinamide blocked the peroxide level induced by H2O2 or UVC irradiation. Decrease of H2O2 or UVC-induced 8-OH dG in DNA was also detected in nicotinamide trated cells. The results of present study firstly demonstrated that nicotinamide prevented cells from H2O2 and UVC irradiation induced apoptosis through suppression ROS production, p53 elevation and 8-OH dG formation. Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=10656 [article]

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Solving injection molded part warpage under asymmetric mold cooling conditions by corrugated variations in part thickness / S. C. Chen in INTERNATIONAL POLYMER PROCESSING, Vol. XXVII, N° 1 (03/2012)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXVII, N° 1 (03/2012) . - p. 3-8 Titre : Solving injection molded part warpage under asymmetric mold cooling conditions by corrugated variations in part thickness Type de document : texte imprimé Auteurs : S. C. Chen, Auteur ; Y. Chang, Auteur ; S. T. Huang, Auteur Année de publication : 2012 Article en page(s) : p. 3-8 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Matières plastiques -- Moulage par injection Tags : 'Variation  carton  ondulé'  épaisseur'  'Pièce  moulée'  'Moulage  injection'  'Réduction  gauchissement' Index. décimale : 668.4 Plastiques, vinyles Résumé : In this study, corrugated variations in part thickness designed to match the various mold temperature differences between the mold core and mold cavity sides, along with their effects on part warpage, were investigated. Part thickness was varied in a pitched manner and thickness reductions of 10 %, 20 %, 30 %, and 40 % of the original part thickness were implemented. The results show that when there is a mold temperature difference between core and cavity, using a corrugated thickness reduction design can greatly reduce or even eliminate part warpage. For a uniform thickness part molded under unbalanced cooling, the thermal neutral axis (where the maximum melt temperature is located) will deviate from the gap center toward the mold wall side with the higher temperature. Variation in thickness will pull the deviated thermal neutral axis back to the center line leading to a reduction in part warpage. DOI : 10.3139/217.2492 En ligne : https://drive.google.com/file/d/1Mhn1FgTAbvlH_iwuz9FDdcq4uoo3Zrt-/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=13715 [article]

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