HAL (Le Centre pour la Communication Scientifique Directe), Sep 3, 2019
Mechanisms of action are revisited through two case studies: (i) soot morphology released from EV... more Mechanisms of action are revisited through two case studies: (i) soot morphology released from EVA and EVA/ATH and (ii) anisotropy of heat gradient in intumescent PP.
HAL (Le Centre pour la Communication Scientifique Directe), May 20, 2019
Polyolefins are used in a plethora of application fields: building, automotive, railways, E&E... more Polyolefins are used in a plethora of application fields: building, automotive, railways, E&E… Those fields are concerned by fire regulations and the inherent flammability of polyolefins can be the source of fire hazards. Intumescence was selected to provide polyolefins with flame retardancy. The intumescence process results from a combination of charring and foaming at the surface of the substrate. The intumescent coating expands and forms an insulative layer at the surface of the substrate upon heating. The charred layer acts as a physical barrier, which slows down heat and mass transfer between gas and condensed phase. The formation of an intumescent char is a complicated process involving several critical aspects: rheology (expansion phase, viscoelasticity of char), chemistry (charring) and thermophysics (limitation of heat and mass transfer). The purpose of the talk is to develop new formulations for polyolefins (in particular polypropylene (PP) and ethylene-vinyl acetate copolymer (EVA)). The concept is to use additional ingredients in basic intumescent formulation to create synergistic effect. It is shown zinc carbonate can reduce significantly peak of heat release rate (pHRR) in intumescent EVA. In order to investigate the mechanism of action, the tests are instrumented (thermocouples in the samples, IR thermography …) to get information on the fire behavior of the samples. Advanced analyses (MTGA, kinetic analysis, solid state NMR, X-ray tomography …) are also employed. Finally, new intumescent formulations are suggested to optimize FR performance in polyolefins.
Dans un objectif de developpement et d’optimisation de nouvelles formulations de gaine d’isolatio... more Dans un objectif de developpement et d’optimisation de nouvelles formulations de gaine d’isolation de câble electrique basse tension, il a ete necessaire d’adapter et de concevoir des tests a l’echelle du laboratoire. De nos jours, la normalisation des câbles electriques ne prend pas en compte la mise sous tension lors de la caracterisation de leur comportement au feu. Or, dans un incendie, les câbles electriques sont le plus souvent alimentes par differentes intensites. L’originalite des tests developpes dans ce memoire est l’evaluation du comportement au feu des formulations de gaine isolante de câble electrique lorsqu’ils sont soumis a differents scenarios ou les câbles sont alimentes par differentes intensites. Pour realiser ce projet, deux methodologies de test se basant sur un modele feu connu ont ete utilisees et adaptees pour permettre la mise sous tension des echantillons. Ces deux methodologies sont une etude au cone calorimetre et une etude de la propagation de la flamme ...
HAL (Le Centre pour la Communication Scientifique Directe), Sep 3, 2019
Mechanisms of action are revisited through two case studies: (i) soot morphology released from EV... more Mechanisms of action are revisited through two case studies: (i) soot morphology released from EVA and EVA/ATH and (ii) anisotropy of heat gradient in intumescent PP.
HAL (Le Centre pour la Communication Scientifique Directe), May 20, 2019
Polyolefins are used in a plethora of application fields: building, automotive, railways, E&E... more Polyolefins are used in a plethora of application fields: building, automotive, railways, E&E… Those fields are concerned by fire regulations and the inherent flammability of polyolefins can be the source of fire hazards. Intumescence was selected to provide polyolefins with flame retardancy. The intumescence process results from a combination of charring and foaming at the surface of the substrate. The intumescent coating expands and forms an insulative layer at the surface of the substrate upon heating. The charred layer acts as a physical barrier, which slows down heat and mass transfer between gas and condensed phase. The formation of an intumescent char is a complicated process involving several critical aspects: rheology (expansion phase, viscoelasticity of char), chemistry (charring) and thermophysics (limitation of heat and mass transfer). The purpose of the talk is to develop new formulations for polyolefins (in particular polypropylene (PP) and ethylene-vinyl acetate copolymer (EVA)). The concept is to use additional ingredients in basic intumescent formulation to create synergistic effect. It is shown zinc carbonate can reduce significantly peak of heat release rate (pHRR) in intumescent EVA. In order to investigate the mechanism of action, the tests are instrumented (thermocouples in the samples, IR thermography …) to get information on the fire behavior of the samples. Advanced analyses (MTGA, kinetic analysis, solid state NMR, X-ray tomography …) are also employed. Finally, new intumescent formulations are suggested to optimize FR performance in polyolefins.
Dans un objectif de developpement et d’optimisation de nouvelles formulations de gaine d’isolatio... more Dans un objectif de developpement et d’optimisation de nouvelles formulations de gaine d’isolation de câble electrique basse tension, il a ete necessaire d’adapter et de concevoir des tests a l’echelle du laboratoire. De nos jours, la normalisation des câbles electriques ne prend pas en compte la mise sous tension lors de la caracterisation de leur comportement au feu. Or, dans un incendie, les câbles electriques sont le plus souvent alimentes par differentes intensites. L’originalite des tests developpes dans ce memoire est l’evaluation du comportement au feu des formulations de gaine isolante de câble electrique lorsqu’ils sont soumis a differents scenarios ou les câbles sont alimentes par differentes intensites. Pour realiser ce projet, deux methodologies de test se basant sur un modele feu connu ont ete utilisees et adaptees pour permettre la mise sous tension des echantillons. Ces deux methodologies sont une etude au cone calorimetre et une etude de la propagation de la flamme ...
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