An Insight into the Flammability of Some Bio-Based Polyesters

The heat release capacity of polymers can be generally predicted using a method based on the additivity of group contributions (the Van Krevelen approach). Nevertheless, there are some exceptions, evidencing that this approach is insufficient and must be completed. In this study, the kinetic triplet accounting for the description of pyrolysis is identified for 11 polymers. Activation energy and the frequency factor are calculated using Kissinger’s method. Reaction models are chosen among the Avrami–Erofeev functions. The high flammability of poly(3-hydroxybutyrate) and the underestimation of its heat release capacity using the Van Krevelen approach are explained from these parameters. The results highlight the possibility of improving the model, using additional but easily accessible data

How to study the two-step decomposition of polymer blends in cone calorimeter?

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How to study the two-step decomposition of polymer blends in cone calorimeter?

International audienc

Maîtrise et caractérisation de l’ignifugation de fibres de chanvre

Pau dans : Academic Journal of Civil Engineering, Vol 40 No 1 (2022): Special Issue - RUGC 2022, p 236-239National audienceL’introduction de ressources végétales dans la formulation des matériaux permet de réduire l’impact environnemental du secteur de la construction. Cette étude vise à développer un traitement ignifugeant adapté aux isolants thermiques à base de fibres de chanvre. Le but est de limiter les impacts énergétiques, sanitaires et environnementaux du traitement, tout en optimisant les performances techniques des produits traités. Un protocole de laboratoire est mis en place pour évaluer l’effet retardateur de flamme du traitement. Les fibres traitées avec des solutions commerciales ou des formulations spécifiques sont soumises à différents essais de caractérisation incluant des essais d’inflammation directe, des essais à la petite flamme, des analyses thermiques (ATD-TG) et des essais au calorimètre à cône. Les résultats obtenus permettent d’orienter la formulation d’un traitement mais mettent également en évidence la complémentarité de ses méthodes d’analyse. Le couplage des résultats permet également de proposer un ajustement de modèles prédictifs conduisant à l’estimation du classement de réaction au feu selon l’Euroclasse des matériaux testé

Ignifugation des fibres de chanvre dans l'isolation thermique vrac

International audienceL’utilisation de ressources végétales dans la formulation des matériaux permet de réduire l’impact environnemental du secteur de la construction. De telles ressources restent sensibles au feu. Cette étude vise à développer un traitement ignifugeant adapté aux isolants thermiques à base de fibres de chanvre. Le but est de limiter les impacts sanitaires et environnementaux du traitement, tout en optimisant les performances techniques des produits traités. Un protocole de laboratoire est mis en place pour évaluer l’effet retardateur de flamme du traitement. Les fibres traitées avec des solutions commerciales ou des formulations spécifiques sont soumises à différents essais de caractérisation incluant des essais d’inflammation directe, des essais à la petite flamme, des analyses thermiques (ATD-TG) et des essais au calorimètre à cône. Les résultats obtenus permettent d’orienter la formulation d’un traitement mais mettent également en évidence la complémentarité de ces méthodes d’analyse. Le couplage des résultats permet également de proposer un ajustement de modèles prédictifs conduisant à l’estimation du classement de réaction au feu selon l’Euroclasse des matériaux testés

Characterization of hemp fiber fire reaction

International audienceIntegrate bio-resources in materials allows to reduce the environmental impact of the building industry. This study deals with fire-retardant treatment, alternative to boric acid and ammonium salts solutions, applied to hemp fibers for thermal insulation application. The aim is to limit the energy, sanitary and environmental impacts of the treatment, while optimizing the technical performances. A laboratory protocol evaluates the flame-retardant effect of the developed treatments. Treated fibers, including commercial treatments, are subjected to characterization tests: direct ignition small flame, thermal analysis (ATD-TG), cone calorimeter and pyrolysis-combustion flow calorimeter analyses. Some of the methods have been adapted to be applied to fibrous materials. The obtained results orientate the formulation of a treatment and highlight the complementarity of the analysis methods. Coupling the results, a predictive model leading to the estimation of the reaction to fire classification according to the Euroclass is proposed. Euroclass C is probably accessible with tailored treatment

Fire behavior of innovative alginate foams

International audienceA new biosourced composite foam (AF, associating foamed alginate matrix and orange peel filler) is successfully tested for fire-retardant properties. This material having similar thermal insulating properties and density than fire-retardant polyurethane foam (FR-PUF, a commercial product) shows promising enhanced properties for flame retardancy, as assessed by different methods such as thermogravimetric analysis (TGA), pyrolysis combustion flow calorimetry (PCFC) and a newly designed apparatus called RAPACES for investigating large-scale samples. All these methods confirm the promising properties of this alternative material in terms of fire protection (pHRR, THR, EHC, time-to-ignition, flame duration or production of residue), especially for heat flux not exceeding 50 kW m−2. At higher heat flux (i.e., 75 kW m−2), flame retardant properties tend to decrease but maintain at a higher level than FR-PUF. The investigation of the effect of AF thickness shows that the critical thickness (CT) is close to 1.5–1.7 cm: heat diffusion and material combustion are limited to the CT layer that protects the underlying layers from combustion. A multiplicity of factors can explain this behavior, such as: (a) negligible heat conduction, (b) low heat of combustion, (c) charring formation, and (d) water release. Water being released from underlying layers, dilutes the gases emitted during the combustion of superficial layers and promotes the flame extinction

Influence of Ammonium Polyphosphate/Lignin Ratio on Thermal and Fire Behavior of Biobased Thermoplastic: The Case of Polyamide 11

Flame retardancy of polymers is a recurring obligation for many applications. The development trend of biobased materials is no exception to this rule, and solutions of flame retardants from agro-resources give an advantage. Lignin is produced as a waste by-product from some industries, and can be used in the intumescent formation development as a source of carbon combined with an acid source. In this study, the flame retardancy of polyamide 11 (PA) is carried out by extrusion with a kraft lignin (KL) and ammonium polyphosphate (AP). The study of the optimal ratio between the KL and the AP makes it possible to optimize the fire properties as well as to reduce the cost and facilitates the implementation of the blend by a melting process. The properties of thermal decomposition and the fire reaction have been studied by thermogravimetric analyzes, pyrolysis combustion flow calorimetry (PCFC) and vertical flame spread tests (UL94). KL permits a charring effect delaying thermal degradation and decreases by 66% the peak of heat release rate in comparison with raw PA. The fire reaction of the ternary blends is improved even if KL-AP association does not have a synergy effect. The 25/75 and 33/67 KL/AP ratios in PA give an intumescence behavior under flame exposure

Flame retardant PP/PA6 blends: A recipe for recycled wastes

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