Evaluation of properties and biodeterioration potential of polyethylene and aliphatic polyester blends / A. V. Machado in INTERNATIONAL POLYMER PROCESSING, Vol. XXII, N° 5 (11/2007)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XXII, N° 5 (11/2007) . - p. 512-518 Titre : Evaluation of properties and biodeterioration potential of polyethylene and aliphatic polyester blends Type de document : texte imprimé Auteurs : A. V. Machado, Auteur ; I. Moura, Auteur ; Fernando M. Duarte, Auteur ; G. Botelho, Auteur ; R. Nogueira, Auteur ; A. G. Brito, Auteur Année de publication : 2007 Article en page(s) : p. 512-518 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : Blends of high density polyethylene (HDPE) and biodegradable polymers - polylactic acid, PLA, poly(e-caprolactone), PCL and Mater-Bi|Superscript|®|/Superscript| (thermoplastic starch (TPS) with PLA or PCL) - were prepared in a co-rotating twin-screw extruder, together with polyethylene modified with maleic anhydride (PE-g-MA) used as compatibiliser. The mechanical and rheological properties, morphology and potential for biodeterioration of polymeric materials were evaluated. Blends with PLA showed a reduced elongation at break but an increased Young's modulus while the addition of PCL led to materials with a greater elongation at break and a lower Young modulus. The rheological results evidenced that HPDE and the blend with the highest TPS level exhibited the highest viscosity. The microbial growth test carried out to evaluate the potential for biodeterioration of the blends, using a pure culture of Pseudomonas fluorescens, indicated that HDPE/PCL had a lower resistance to bacterial attack than the blend of HDPE/PLA. This was verified by a higher cell number on its surface after 10 weeks of incubation. The addition of 30 % starch to the HDPE/PLA blend enhanced its biodeterioration potential, the same was not observed in the case of the HDPE/PCL blend containing just 18 % starch. DOI : 10.3139/217.2061 En ligne : https://drive.google.com/file/d/1myfOtTmtR596MF4nE8fO30WaD6g4zw73/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=2693 [article]

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Improving the thickness distribution of parts with hybrid thermoforming / Fernando M. Duarte in INTERNATIONAL POLYMER PROCESSING, Vol. 37, N° 4 (2022)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. 37, N° 4 (2022) . - p. 396-405 Titre : Improving the thickness distribution of parts with hybrid thermoforming Type de document : texte imprimé Auteurs : Fernando M. Duarte, Auteur ; Catarina G. Ribeiro, Auteur ; João G. Ferreira, Auteur ; Sílvia A. Forte, Auteur ; Jose A. Covas, Auteur Année de publication : 2022 Article en page(s) : p. 396-405 Note générale : Bibliogr. Langues : Anglais (eng) Catégories : Etat fondu (matériaux) Filaments Fibre de longueur infinie ou extrême comme celle qu'on trouve dans la soie à l'état naturel. Les fibres manufacturées sont extrudées en filaments qui sont transformés en fils continus, en fibres courtes ou en câbles. Lasers -- Applications industrielles Matériaux -- Epaisseur Matières plastiques -- Thermoformage Usinage par laser Index. décimale : 668.4 Plastiques, vinyles Résumé : With the aim of improving the thickness gradient of thermoformed parts, and thus increase their performance and/or reduce their weight, the concept of hybrid thermoforming is introduced, whereby local thickness differences in extruded sheets are created prior to thermoforming. Material is removed by CO2 ablation or 3D printing of an over-thickness at specific locations of sheets previously extruded. The feasibility and potential usefulness of the approach is explored experimentally for the production of a truncated conical cup, since this is a well-characterized application. The conventional thickness distributions obtained by conventional vacuum forming are significantly changed with the new strategy and can be tuned by adequately selecting the locations and amount of material do be removed and/or added. Note de contenu : The concept of hybrid thermoforming Experimental Results and discussion : Removing material approach - Adding material approach DOI : https://doi.org/10.1515/ipp-2022-4222 En ligne : https://drive.google.com/file/d/1_k1niD222mz_teTTN-MJkmmodAET_QPd/view?usp=shari [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=37915 [article]

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On the use of the heating stage to control the thickness distribution in thermoformed parts / Fernando M. Duarte in INTERNATIONAL POLYMER PROCESSING, Vol. XIX, N° 2 (06/2004)  

[article]  inINTERNATIONAL POLYMER PROCESSING > Vol. XIX, N° 2 (06/2004) . - p. 186-198 Titre : On the use of the heating stage to control the thickness distribution in thermoformed parts Type de document : texte imprimé Auteurs : Fernando M. Duarte, Auteur ; Jose A. Covas, Auteur Année de publication : 2004 Article en page(s) : p. 186-198 Note générale : Bibliogr. Langues : Anglais (eng) Index. décimale : 668.9 Polymères Résumé : This work investigates the influence of the heating stage of rollfed and sheet-to-sheet thermoforming on the thickness uniformity of the final parts produced. Modeling of the heat transfer process involved in each case is carried out. An inverse methodology capable of setting the temperature of the heaters that produce a prescribed sheet temperature at the end of the heating stage is presented. The sensitivity of this differential heating technique to moderate perturbations of the individual set values is analyzed. DOI : 10.3139/217.1821 En ligne : https://drive.google.com/file/d/1cnuzP0A4uA8qUQwACQ-b3I9OHkEfXYjq/view?usp=drive [...] Format de la ressource électronique : Pdf Permalink : https://e-campus.itech.fr/pmb/opac_css/index.php?lvl=notice_display&id=3287 [article]

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