Controlled Emissivity Coatings to Delay Ignition of Polyethylene

International audienceSemi-opaque to opaque films containing small amounts of various aluminium particles to decrease emissivity were easily prepared and coated onto low-density polyethylene (LDPE) sheets. The thermal-radiative properties (reflectivity, transmissivity and absorptivity) of the films were measured and related to the aluminum particles' content, size and nature. Time-to-ignition of samples was assessed using a cone calorimeter at different heat flux values (35, 50 and 75 kW/m 2). The coatings allowed significant ignition delay and, in some cases, changed the material behaviour from thermally thin to thick behaviour. These effects are related both to their emissivity and transmissivity. A lower emissivity, which decreases during the degradation, and a lower transmissivity are the key points to ensure an optimal reaction-to-fire

Influencia de diferentes parámetros en el comportamiento al fuego de siete especies de frondosas mejicanas

En este artículo se analiza el comportamiento al fuego de siete maderas frondosas mejicanas. La finalidad es intentar determinar cuáles son los parámetros que ejercen influencia en el comportamiento al fuego de la madera. Uno de los factores que se considera clave es la densidad, ya que está relacionada con la velocidad de carbonización y por consiguiente esto afecta a las reacciones de pirólisis. Sin embargo, la densidad no es el único factor que influye en el comportamiento al fuego de la madera. En este trabajo se estudian siete frondosas diferentes y se analizan los resultados de los ensayos de reacción al fuego en relación a las propiedades físicoquímicas de la madera.Peer ReviewedPostprint (published version

Effect of post curing temperature on mechanical properties of a flax fiber reinforced epoxy composite

International audienceAchieving a complete curing of biocomposites without damaging fibers is very challenging. This study assesses the impact of processing upon the mechanical properties of a unidirectional flax reinforced epoxy composite and identifies which component (resin, reinforcement or interphase) is the most sensitive to post-curing at high temperature (100, 120 or 150 °C).Post-curing temperature had a limited impact on the composite mechanical behavior excepted at 150 °C where ultimate stress and strain decreased drastically while the stabilized modulus slightly increases.Post curing is responsible of a slight decrease of the matrix tensile properties attributed to the polymer oxidation but cannot explain on its own the evolution of the composite behavior. Interfacial adhesion played a minor role in the composite behavior probably due to its intrinsic weakness. Finally, the flax fabric was highlighted to be the component most sensitive to thermal treatment thus governing the drop in the composite mechanical properties

Controlled Emissivity Coatings to Delay Ignition of Polyethylene

Semi-opaque to opaque films containing small amounts of various aluminium particles to decrease emissivity were easily prepared and coated onto low-density polyethylene (LDPE) sheets. The thermal-radiative properties (reflectivity, transmissivity and absorptivity) of the films were measured and related to the aluminum particles’ content, size and nature. Time-to-ignition of samples was assessed using a cone calorimeter at different heat flux values (35, 50 and 75 kW/m2). The coatings allowed significant ignition delay and, in some cases, changed the material behaviour from thermally thin to thick behaviour. These effects are related both to their emissivity and transmissivity. A lower emissivity, which decreases during the degradation, and a lower transmissivity are the key points to ensure an optimal reaction-to-fire

Compatibilization of PE/GTR by irradiation

International audienc

Ignifugation des élastomères – Quelques stratégies

National audienc

Compatibilization of PE/GTR by irradiation

International audienc

Intrinsic Smoke Properties and Prediction of Smoke Production in National Bureau of Standards (NBS) Smoke Chamber

Smoke production in a smoke chamber is characterized by the accumulation of smoke and the continuous consumption of oxygen leading to a vitiated atmosphere. However, a method is proposed to predict the smoke evolution in a smoke chamber at 25 kW/m2 by using material properties calculated from a cone calorimeter, as already shown in a previous article. These properties represent the ability of a material to produce smoke at a specific mass loss rate. The influence of a flame retardant on these properties can be used as a quantitative measurement of its action on smoke production. These properties can be calculated at another heat flux than 25 kW/m2. The knowledge of the curve “mass loss rate = f(time)” in a smoke chamber is still required, but this curve is close to that measured in a cone calorimeter at the same heat flux. The results prove that the smoke production in a smoke chamber and cone calorimeter is qualitatively similar, i.e., the decrease of oxygen content in a smoke chamber has no influence on smoke (at least as long as optical density does not exceed 800)

Ignifugation des élastomères – Quelques stratégies

National audienc

Use of Pyrolysis Combustion Flow Calorimetry (PCFC) to predict the flammability parameters of polymers from their chemical structure

International audienc