New Insights into the Investigation of Smoke Production Using a Cone Calorimeter

International audienc

Thermal degradation, flammability, and potential toxicity of polymer nanocomposites

International audienceMany new nanomaterial-based products have been developed recently, due to advances in nanotechnology. These are designed to offer new functionalities or to modify existing products. This chapter examines the thermal degradation and flammability of various nanocomposite polymers and the potential risks of burning them. Different fire scenarios have been simulated with a cone calorimeter coupled with FTIR, condensation nuclei counter (CNC) analysers, and/or cascade impactors in order to produce aerosols emitted at different radiation levels and flammable atmospheres. The testing conditions and influential parameters are presented. Combinations of pristine ultrafine particles with soot or other ultrafine particles during thermal degradation can directly affect human health. Hence, more research is needed into the morphology and composition of the released nano-objects and ultrafine particles

High-performance fire-retardant polyamide materials

International audienc

Dimensional measurement of TiO2 particles in powder form by SAXS and SEM

International audienceDevelopments of nanomaterials had an important known evolution during the last thirty years fordifferent industrial sectors1. Titanium dioxide is one of the most produced and exploited nanomaterialsin the industry2. Indeed, TiO2 has various applications; it can be used as a white pigment for paint andfood products and is also used as a UV filter in sunscreen lotions. The characterization of TiO2nanoparticles, contained in consumer products remains a challenge because of their structure(polydispersity, polymorphism) and their environment which remains generally complex and requiresseveral characterizations techniques. Electron microscopies are the first recommended techniques forthe dimensional characterization of nanomaterials. In comparison with the results obtained by thescanning electron microscope (SEM), another technique, SAXS (Small Angle X-Ray Scattering), can beused for the indirect characterization of nanomaterials (simple or introduced into a complex matrix).The first step of this study is to compare the dimensional measurements of TiO2 nanoparticles in powderform with two different techniques: SEM (direct method) and SAXS (indirect method) and with twodifferent measurands, an equivalent area diameter for SEM and specific surface area for SAXS. Thesecond part should be to avoid the sampling preparation steps with in situ dimensional measurement

Influence of the composition of PMMA nanocomposites on gaseous effluents emitted during combustion

International audienceThis paper focuses on the nature of thermal degradation products formed by combustion of various PMMA nanocomposites and on the kinetics of emission of gases emitted during combustion. Compositions of two kinds of nanosilica and nanoalumina and their combinations with Ammonium Poly-Phosphate (APP) in PMMA were prepared. Their thermal degradation was carried out using TGA coupled with FTIR and cone calorimeter. For the compositions of nanooxides, it appears that the kinetics of emission of gases is significantly influenced by the nature of oxide and by the surface treatment, but mainly for silica. Octylsilane modified silica combined with APP leads to an outstanding fire behaviour, due to the formation of a very cohesive and expanded layer containing silicon pyrophosphate, but at the expense of a higher CO emission and a measurable emission of HCN. Even if the presence of fire retardant (APP) and the incorporation of nanosilica with a surface treatment reduce the flammability, the high value of the CO yield could lead to the conclusion that the combination could improve toxicity. But, the nanocomposite based on silica surface treatment coupled with APP, induce a delay of the CO yield emission, which could allow people to evacuate buildings or houses in case of fire

Material integrity and fate of particulates released from carbon fibre composites containing nanomaterials during simultaneous fire and impact

Nanomaterials are usually incorporated in the polymeric resin matrix of the carbon fibre-reinforced composites (CFC) to enhance their mechanical and thermal performances. CFCs when exposed to heat/fire and impact such as in an aeroplane/transport vehicle crash, are known to release small carbon fibres, some of which could be of nanosized diameters and hence airborne. While this is still an under researched area, there is no information available on the fate of CFCs containing nanomaterials in such scenarios. To address this, we have recently developed a methodology to subject CFCs to simultaneous heat/fire and impact and collect all of the released debris from the front/back faces plus the effluents of the heated/burning composite. CFCs containing nanomaterials, namely layered double hydroxides (LDH), nanotubes (NT) and graphene oxide (GO) were subjected to varying radiant heat fluxes and 19J low velocity impact. Particle size distribution of released particles was conducted by image analysis of SEM micrographs and their agglomeration behaviour by zeta potential measurement. The presence of nanomaterials did not significantly affect the particle size distribution of the released particles; however, the heat duration and the fire had a noticeable effect, the particle size decreased with increasing heat flux and duration. From the particle size distribution and agglomeration behaviours their potential health hazards could be contemplated

Dimensional measurement of TiO2_2 (Nano) particles by SAXS and SEM in powder form

International audienceThe market for nano-additive materials has been growing exponentially since 2012, with almost 5040 consumer products containing nanoparticles in 2021. In parallel, the increasing recommendations, definitions and legislations underline the need for traceability of manufactured nanoparticles and for methods able to identify and quantify the “nano” dimensional character in manufactured product. From a multi-technic approach, this paper aims to compare the mesurands extracted from SAX/BET (specific surface area) and SEM (diameter equivalent to a projected surface area) on different TiO$_2$ powder issued from referenced, synthesized materials, raw materials (additives) and extracted materials from manufactured products. The influence of various parameters such as the anisotropic factor, the interaction between particles, the size distribution and the extraction steps are discussed to illustrate their impact on the diameter values issued from two different measurands. These results illustrate the difficulties in (nano)particles characterization. SEM and SAXS are complementary technics depending on the level of dimensional characterization required