30 research outputs found

    Taguchi method modelling of Nd:YAG laser ablation of microchannels on cyclic olefin polymer film

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    This paper presents the development of a model for Nd:YAG laser ablation of cyclic olefin polymer (COP) films. Two Taguchi orthogonal array experimental designs were implemented to produce a model for the prediction of microchannel depth and width produced on ZeonorFilmŸ ZF14 and ZF16 polymer films via laser ablation. The width and depth of the produced microchannels were measured using 3D optical profilometry. Microchannels produced were seen to range in depth of up to 50 ”m, and widths of 112 ”m via single-pass laser depending on the grade of COP, with feature size increasing as the number of laser passes increased. The models are discussed in terms of adjusted coefficient of determination, signal to noise ratio and model significance. The effect of the process parameters used such as fluence and scan speed on three different grades of COP was examined with an aim to produce a simple model suitable for predictive control of surface microstructuring of COP

    Biosourced polymers derived from LTTM {glucide polycarboxylic acid water} : Elaboration and applications in refractory carbonaceous materials

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    Les matĂ©riaux composites carbone/carbone rĂ©fractaires sont constituĂ©s de charges granulaires carbonĂ©es mises en forme Ă  l’aide d’un liant carbonisable. Jusqu’à prĂ©sent, le liant utilisĂ© est gĂ©nĂ©ralement le brai de goudron houille, cancĂ©rigĂšne et visĂ© par REACH. Afin de le substituer par un produit plus respectueux de l’environnement et de la santĂ© des manutentionnaires, nous proposons une solution innovante dans ces travaux de thĂšse. Les glucides, et plus particuliĂšrement les sucres, sont des composĂ©s carbonisables possĂ©dant un rendement en carbone faible. En prĂ©sence de polyacide carboxylique, ceux-ci peuvent former un mĂ©lange Ă  transition de phase basse tempĂ©rature se caractĂ©risant par un eutectique ou une tempĂ©rature d’écoulement plus faible que celle de ses constituants pris sĂ©parĂ©ment. Ce type de mĂ©lange est capable de rĂ©agir Ă  des tempĂ©ratures de l'ordre de 100 °C, donc infĂ©rieures Ă  celles communĂ©ment requises pour des rĂ©actions d'estĂ©rification. Ce comportement s'apparente Ă  celui dĂ©jĂ  dĂ©crit pour les BADES (BrĂžnsted Acidic Deep Eutectic Solvent). Dans ces conditions sont obtenus des copolymĂšres (ester-co-oside) linĂ©aires et branchĂ©s qui conduisent Ă  un rĂ©seau poly(ester-co-oside) en poursuivant la rĂ©action sous vide. Par le choix des constituants et le contrĂŽle du temps de rĂ©action, il est possible de piloter la viscositĂ© des polymĂšres pour les utiliser comme liant dans des composites carbone/carbone Ă  charges granulaires. Dans ce cas, nous avons montrĂ© que l’utilisation de polyacides carboxyliques prĂ©sente trois avantages : i) en mĂ©lange avec des sucres, des LTTMs (Low Transition Temperature Mixtures) liquide Ă  tempĂ©rature ambiante sont formĂ©s, ce qui facilite leur utilisation dans le procĂ©dĂ©, ii) ils servent de rĂ©actif et de catalyseur pour la polymĂ©risation des sucres et iii) ils permettent d’augmenter le rendement en carbone des liants. Ces rĂ©sultats sont trĂšs prometteurs pour la fabrication de composites carbone/carbone rĂ©fractaire comme Ă©lectrode pour l’électrolyse de l’alumine.Refractory carbon/carbon composite materials consist of carbonaceous granular fillers shaped with a carbonisable binder. Until now, the binder used has generally been coal tar pitch, which is carcinogenic and covered by REACH. In order to replace it with a product that is more respectful of the environment and of the health of handlers, we are proposing an innovative solution in this thesis work. Carbohydrates, and more particularly sugars, are carbonisable compounds with a low carbon yield. In the presence of polycarboxylic acid, they can form a low transition temperature mixtures characterised by a eutectic or a lower flow temperature than that of its constituents taken separately. This type of mixture is capable of reacting at temperatures of the order of 100°C, thus lower than those commonly required for esterification reactions. This behaviour is similar to that already described for BADES (BrĂžnsted Acidic Deep Eutectic Solvent). Under these conditions, linear and branched (ester-co-oside) copolymers are obtained which lead to a poly(ester-co-oside) network by continuing the reaction under vacuum. By choosing the constituents and controlling the reaction time, it is possible to control the viscosity of the polymers for use as a binder in carbon/carbon composites with granular fillers. In this case, we have shown that the use of polycarboxylic acids has three advantages: i) when mixed with sugars, LTTMs (Low Transition Temperature Mixtures) that are liquid at room temperature are formed, which facilitates their use in the process, ii) they act as a reagent and catalyst for the polymerisation of sugars and iii) they make it possible to increase the carbon yield of the binders. These results are very promising for the manufacture of refractory carbon/carbon composites as an electrode for alumina electrolysis
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