221 research outputs found
Fire retardant action of mineral fillers
Endothermically decomposing mineral fillers, such as aluminium or magnesium hydroxide, magnesium carbonate, or mixed magnesium/calcium carbonates and hydroxides, such as
naturally occurring mixtures of huntite and hydromagnesite are in heavy demand as sustainable, environmentally benign fire retardants. They are more difficult to deploy than the
halogenated flame retardants they are replacing, as their modes of action are more complex, and are not equally effective in different polymers. In addition to their presence (at levels up to 70%), reducing the flammable content of the material, they have three quantifiable fire
retardant effects: heat absorption through endothermic decomposition; increased heat capacity of the polymer residue; increased heat capacity of the gas phase through the presence of water or carbon dioxide. These three contributions have been quantified for eight of the most common fire retardant mineral fillers, and the effects on standard fire tests such as the LOI, UL 94 and cone calorimeter discussed. By quantifying these estimable
contributions, more subtle effects, which they might otherwise mask, may be identified
Thermal stability and degradation kinetics of poly(methyl methacrylate)/layered copper hydroxy methacrylate composites
Fire retardancy of melamine and zinc aluminum layered double hydroxide in poly(methyl methacrylate)
Magnetite-poly(lactic-co-glycolic acid) hybrid particles: Preparation and viscoelastic properties
Effect of magnesium dihydroxide nanoparticles on thermal degradation and flame resistance of PMMA nanocomposites
Polyméthacrylate de méthyle (PMMA) : Développement de nouveaux systèmes retardateurs de flamme à base de nanocharges minérales. Recherche de synergies avec des montmorillonites et des composés phosphorés
The poly(methyl methacrylate) (PMMA) is a very interesting thermoplastic polymer. It finds many applications in many sectors and particularly in the field of lighting (lamps, signs...). However, like many polymers, it is easily flammable and its fireproofing is an important commercial stake, especially as the norms in the matter are more and more stricts (halogen-free compounds). Among the methods of improvement of the fire resistance of polymers, one of the most used consists in incorporating in the polymeric matrix particles of inorganic compounds. Among those, clays of the montmorillonite type are particularly promising by ensuring the construction of a silicato-carbonized layer at the surface of the polymer during its combustion. Nevertheless, the majority of the performed studies show the need for using these lamellar particles in combination with other flame retardant additives in order to obtain a flame behaviour fully meeting the norms in use. Among these additives, are the metallic oxide nanoparticles. The principal objective of this work was the study of the effect of some metal oxides or hydroxides, with different features (size and specific surface area), on the thermal stability and fire resistance of PMMA. Then, synergies were investigated between the oxides considered as the most interesting (particularly, the nanometric ones) and an organo-modified montmorillonite (OMMT) or with various commercial phosphorated flame retardant additives.Le polyméthacrylate de méthyle (PMMA) est un matériau polymère thermoplastique très intéressant. Il trouve de nombreuses applications dans de nombreux secteurs et particulièrement dans le domaine de l'éclairage (lampes, enseignes,...). Comme de nombreux polymères, il est cependant facilement inflammable et son ignifugation est un enjeu commercial important d'autant plus que les normes en la matière sont de plus en plus sévères (absence de composés halogénés).Parmi les méthodes d'amélioration du comportement au feu des polymères, une des plus utilisées consiste à incorporer à la matrice polymère des particules de composés minéraux. Parmi ceux-ci, les argiles de type montmorillonite sont particulièrement prometteuses en assurant la construction d'une couche barrière silicato-charbonnée à la surface du polymère lors de sa combustion. Néanmoins, la plupart des études menées concluent à la nécessité d'utiliser ces particules lamellaires en combinaison avec d'autres additifs retardateurs de flamme afin d'obtenir un comportement au feu répondant pleinement aux normes en vigueur. Parmi ces additifs, figurent les nanoparticules d'oxydes métalliques. L'objectif principal de ce travail a été l'étude de l'effet de quelques oxydes ou hydroxyde métalliques, de caractéristiques différentes (taille des particules et surface spécifique), sur la stabilité thermique et la résistance au feu du PMMA. Ensuite, nous avons recherché des synergies possibles entre les oxydes jugés les plus intéressants (en particulier nanométriques) et une montmorillonite organo-modifiée (OMMT) ou avec différents additifs retardateurs de flamme phosphorés commerciaux
Barrier effect of flame retardant systems in poly(methyl methacrylate): Study of the efficiency of the surface treatment by octylsilane of silica nanoparticles in combination with phosphorous fire retardant additives
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