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In this paper, CNT modified layered α-MnO2 hybrid flame retardants (α-MnO2–CNTs) were synthesized through one-pot preparation. The structure and composition of the α-MnO2–CNTs hybrid flame retardants were investigated by X-ray diffraction, TEM and SEM. Subsequently, the α-MnO2–CNTs hybrids were then incorporated into epoxy resin (EP) to improve the fire safety properties. Compared with pure EP and the composites with CNTs or α-MnO2, EP/α-MnO2–CNTs composites exhibited improved flame retardancy and smoke suppression properties. With the incorporation of only 2.0 wt% of α-MnO2–CNTs hybrid flame retardants, the peak heat release rate and total heat release of the composites showed 34% and 10.7% reduction respectively. In addition, the volatile gases such as CO and CO2 were reduced and the smoke generation was also effectively inhibited. The improved fire safety of the composites is generally due to the network structures and the synergistic effect of α-MnO2 and CNTs, the catalyzing charring effect, smoke suppression and the physical barrier effect of α-MnO2 nanosheets.

The versatile coating capability of polydopamine (PDA) has received much research interest in numerous fields, including flame retardant functionalization of fillers for polymers. However, the understanding of flame retardant actions of PDA materials in combustion still remains incomplete, limiting its practical applications and future designs as polymer reinforcing fillers. In this study, iron-loaded polydopamine (Fe-PDA) nanospheres were introduced into epoxy resin (EP) as green flame retardant additives. The resultant EP nanocomposites exhibited remarkably reduced flammability, reflected by the high LOI value of 31.6%, V-0 rating in the UL-94 test, as well as a 41% reduction in the peak heat release rate at 5 wt% Fe-PDA loading. More importantly, for the first time, it is clearly revealed that the flame inhibition action in the gas phase was owing to the free radical scavenging ability of Fe-PDA. In addition to the gas phase action, Fe-PDA also promoted the charring process in the condensed phase, leading to the formation of integrated char layers that effectively delayed the mass and heat transfer of combustion. Based on these actions (free radical scavenging and catalytic charring), Fe-PDA acted as the nontoxic and highly efficient flame retardant in EP.

A mesh moving scheme is developed and tested in a finite-volume thermo-mechanical solver to investigate the effects of geometry deformation on thermal protection system materials. Verification case...

Whether pyrolysis gases combustion has effect on surface ablation of charring material is a key issue in the optimization design of thermal protection system for hypersonic vehicles. The coupled method considering combustion of pyrolysis gases in shock layer is presented, realized in MATLAB and validated by comparison with the arcjet experiments. Relationship between surface ablation and mole fraction of oxygen, mass injection rate of pyrolysis gases and surface temperature of charring material under different Mach numbers are predicted by this coupled method. Numerical results indicate that the protective effect of pyrolysis gases combustion on surface ablation is more and more obvious with increase of Mach number. This study is helpful to the optimization of thermal protection system for hypersonic vehicles.

The fabrication of long-lasting flame retardant wool textiles through an eco-friendly scheme is still an urgent task. In the present study, an eco-friendly and innovative hybrid silica sol with core-shell structure was prepared by using phytic acid (PA) as catalyst and dopant for tetraethoxysilane. PA/silica organic-inorganic hybrid sol (PA/silica sol) was then employed to produce durable flame retardant wool fabric using a combined nanoparticle adsorption and pad-dry-cure procedure. The treated wool had enhanced thermal stability and greatly suppressed smoke production capacity. It could still be self-extinguishing after 30 washing cycles. The present approach brought no great negative influence on the handle and mechanical performance of wool fabric. The PA/silica sol network was found to participate in the degradation of the treated wool in the solid phase. The formation of highly inflated char during burning also revealed the flame retarding activity of the PA/silica sol on wool by a condensed charring action. Keywords: Sol-gel, Nanotechnology, Silica, Phytic acid, Wool, Flame retardancy

The direct combustion of typical charring material, with wood as the main representative, has received extensive attention due to its potential as sustainable source of heat and power generation, and the substantial fraction of fuel load in many building fires. In real fire situations, multi-component condensed phase reactants and gas products are involved in the pyrolysis process and the subsequent combustion process. Interestingly, the numerical simulation of these multi-component reactions is relatively not yet well studied. To address this shortcoming, we consider how the reactants can be dealt with using a three-component parallel reaction mechanism and moisture model embedded into the pyrolysis model, wherein the reaction kinetic parameters are optimized by Shuffled Complex Evolution algorithm. The evolved gas products, measured by the TG-FTIR experiment, can be coupled with the extended EDC multi-component combustion model and soot model using FireFOAM. Most of the thermophysical parameters are measured directly by experiments as the input values of simulation. In this work, the predicted results of mass loss rate and heat release rate are compared with experimental data of cone calorimetry, and the good agreement between them validates the applicability of the current multi-component model. Moreover, the effects of three sub-models (three-component parallel reaction mechanism, multiple evolved gas products and the extended EDC multi-component combustion model) are further analyzed based upon the predicted results.

International audience; This paper presents experimental and numerical investigations to access the relative fire structural resistance of thermo-mechanically compressed (or densified) spruce wood. First of all, thermal characterization, including thermal conductivity and specific heat, has been undertaken on both compressed and uncompressed spruce wood. The thermal degradation of both compressed and uncompressed wood has been analysed by means thermogravimetric tests using different heating rates. Both compressed and uncompressed spruce samples of dimensions of 100 mm × 100 mm × 19 mm have been subjected to fire in a cone calorimeter under 20 kW/m2 and 75 kW/m2. Finally, a predictive finite element model based on three-step multi-reactions of pyrolysis is proposed for the thermal transfer and degradation analyses of timber material. The simulated thermal profiles, the mass loss as well as the charring depths were compared to the experimentally recorded results showing a fairly good agreement.

Cross-laminated timber rib panels are floor systems consisting of cross-laminated timber plates rigidly bonded to glued-laminated timber ribs. The composite action is achieved by screw-press gluing using a one-component polyurethane adhesive. The structural behaviour, fire behaviour, and fire resistance were studied using experimental, numerical, and analytical investigations. The overall aim of the thesis was the development of design rules for cross-laminated timber rib panels in fire. The experimental investigations cover ultimate-load tests at normal temperature as reference tests, and fire resistance tests under standard fire exposure on four cross-section types. In addition, shear tests of the glue line between cross-laminated timber plate and glued-laminated timber rib were performed at normal and elevated temperatures for analysis of the cross-sections’ composite action. The results of the reference tests show good agreement with results based on the method of rigidly bonded components and the effective width according to the final European draft of cross-laminated timber design prEN 1995-1-1. The shear tests and the fire resistance tests confirm the assumptions that the glue line remains intact and the effect of the composite action is maintained in fire. The screws remaining after screw-press gluing have negligible influence on the fire behaviour of the floor system. The fire resistance tests show results on the safe side compared to predictions of the fire behaviour according to EN 1995-1-2 and its final draft prEN 1995-1-2. However, the fire resistance is underestimated due to the conservative assumption that the effective width is limited to the rib width in case of fire. The numerical investigations cover thermal, mechanical, and thermo-mechanical simulations using finite-element models. All finite-element models are validated against the experimental results. A new set of temperature-dependent thermal properties for timber exposed to standard fire is proposed to take into account the post-fall-off behaviour in fire. The thermo-mechanical models give good approximations of the cross-sections’ structural behaviour in fire and their fire resistance. A parametric study analyses the structural behaviour in fire, and thus the effective width in fire for a parameter range expected in practice. Design rules are presented for the design of cross-laminated timber rib panels in fire. The effective width in fire is defined depending on the effective width at normal temperature according to prEN 1995-1-1. The analytical investigations are discussed in comparison to the experimental and numerical results using the method of rigidly bonded components for the design in fire. The developed design rules are shown to give safe estimates of the fire resistance.

Post-consumer thermosets are difficult to recycle because, unlike thermoplastics, they cannot be remoulded to create other items as a result of the extensive cross-linkages in their structure. The increased production of thermoset blends and composites in recent years has greatly increased the amount of waste materials. However, higher levels of carbon and hydrogen present in thermosets make them a potential reductant in the iron extractive industries. In this research work, postconsumer thermoset was transformed into carbon resource through a charring process. The resulting carbonaceous material from the thermoset was used as reductant in the production of metallic iron from the Akpafu-Todzi iron ore and artisanal slag using the microwave technology through the composite pellet approach at varying firing times. Analyses by XRF, XRD and SEM/EDS showed that the Akpafu Todzi iron ore is comprised of the iron oxides hematite (Fe2O3) and wustite (Fe0.942O), while the artisanal slag was predominantly fayalite (Fe2SiO4). Complete reduction of the ore was attained after 120 min reduction but the maximum extent of reduction was 78.84% for the slag, demonstrating the potential of postconsumer thermosets to function effectively as a reductant in the iron extractive industry. Keywords: Reduction; Akpafu-Todzi Iron Ore; Post Consumer Thermosets; Waste Electrical Sockets

A series of experiments have been conducted to measure the in‐depth heating of laminated bamboo samples subjected to heat fluxes of 5, 10, 30, and 60 kW/m2, either perpendicular or parallel to the grain. These heat fluxes were chosen to induce different phenomena within the material—from inert heating to moisture evaporation, pyrolysis, oxidation, and flaming—so that the effects of these can be isolated and evaluated separately by simple heat‐transfer models. Moisture migration along the fibres becomes a critical factor when bamboo is heated parallel to the grain, resulting in increased convective heat transfer to deeper parts of the material and an accumulation of moisture in depth that accentuates the endothermic plateau in the temperature profiles around 100°C. Average charring rates for 60 minutes of exposure under 60 kW/m2 were 0.74 and 0.70 mm/min for perpendicular and parallel heating, respectively. The thickness of the heated layer was much larger for parallel heating due to moisture migration, which is less significant perpendicular to the grain. Inert heat diffusion is a good approximation at heat fluxes of 5 and 10 kW/m2, but exothermic oxidation reactions become critical above 400°C and must be included in future models.

Prescribed fire – the intentional use of fire to help achieve a land management goal – is becoming increasingly common as a land management practice. Soil physical, chemical, and biological properties can be affected by prescribed fires, but depend on the fire, soil type, residence time and frequency, and may not be changed substantially in low-severity burns. Here, we examined soil bacterial community composition immediately post-fire (15 days) in a sandy jack pine barrens soil in Wisconsin, USA. Soil bacterial communities clustered significantly by sample site (p

Objectives: To compare “black ring-shaped burn” (BRSB) and charring using spectral computed tomography (CT). Methods: Spectral CT was performed using chicken pectoralis minor muscle, processed in three ways and unprocessed as a control: a) BRSB generated by bringing the negative pole surface of a 3 V button battery (BB) into contact with the muscle; b) BRSB caused by a 1.5 V BB; c) charring caused by broiling; and d) control. Attenuation values were compared between BRSB and charring. Muscles were formalin-fixed and stained with Perls’ Prussian blue. Results: Attenuation values from polychromatic 120-kVp images were significantly higher for BRSBs than for charring. In the spectral Hounsfield unit curve, attenuation values for BRSBs were higher for lower energy. Histopathologically, BRSBs stained positively with Perls’ Prussian blue. Conclusions: This study using spectral CT revealed that BRSB contains metal and confirmed the presence of Fe3+ histopathologically. BRSB differs from charring due to burns. Advances in knowledge: The exact composition of BRSB remains unclear, but this report is the first to show that BRSB differs from charring using spectral CT. Clarification of the composition of BRSB is expected to facilitate the development of more effective BRSB removal therapy.

To have a deep understanding of influence of woodgrain orientation on the upward flame spread performance, a series of tests were conducted to obtain the profile of mass loss rate (MLR), flame spread rate (FSR), total burning duration (TBD), and the maximum flame characteristic length (MFL) by using a traditional flame spreading measurement facility. The woodgrain orientation of samples tested in the current work are horizontal (H), vertical (V), and slanting (S). During the tests, a series of six 2 cm-long 10 cm-wide wood chips were uniformly installed on a vertical sample holder. The distance of air-gap differed from 1.0 cm to 3.0 cm and the thickness of wood chips varied from 1 mm to 4 mm. It is found that flame spread over discrete solid fuels depends on the generation rate of pyrolysis gas and direction of gas-flow, which is highly differed by the woodgrain orientation with respect to the wooden chips. The charring rate of samples imposed a strong effect on the flame spread performance. The a-MLR of three kinds of woodgrain are ranked as V > S > H. The FSR are ranked in general as H > V > S. The thickness of the samples imposed a larger effect on the TBD comparing with wood grains orientation. The TBD are ranked as S > V > H. The results of MFL indicate that as the thickness of the sample increases, MFL of samples performed with the H woodgrain is reduced greatly. However, both S and V woodgrain show a small effect on the MFL. It hopes to provide a deep understanding of flame spreading performance over wooden structures.

The denitrogenative rearrangements of several types of benzotriazoles were investigated by DFT (B3LYP/6-311G(d,p)) and CASPT2(10,10)sp/6-311G(d,p) calculations. The Graebe-Ullmann synthesis of carbazoles 18 by pyrolysis or photolysis of 1-arylbenzotriazoles 14 proceeds without the involvement of benzazirines and without Wolff-type ring contraction to fulvenimines. However, 1-aryltetrahydrobenzotriazoles undergo both cyclization to tetrahydrocarbazole and ring contraction. Triazoloquinones like 34 undergo predominant ring contraction to aminofulvenediones like 38 and also ring expansion to azepinediones like 40 and cyclization to N-arylbenzaziridinediones 39, whereas carbazolediones are not formed. Denitrogenation of 1-methylbenzotriazole 64 results in a facile 1,2-H shift with formation of N-phenylmethanimine 67. 1-Cyanobenzotriazole 71 undergoes destructive pyrolysis with charring, and the calculations predict the occurrence of several low-activation energy reaction pathways.

The main focus of this paper is on the tensile strength of wood at high temperatures. On analysing previous literature, it was observed that results by different researchers are different, even though a vast reduction of the tensile strength at elevated temperatures was clear in all of them. Thus, a need for further investigation into the matter became apparent. As a key part of this paper, steady-state tensile strength experiments below charring temperatures were carried out, and their results were analysed. The results were then used in analysing the tensile strength of a wooden beam subjected to a fire using the Fire Dynamics Simulator.

Flame retardancy is often required in various textile applications. Halogenated flame retardants (FR) are commonly used since they have good FR performance. Several of these components are listed under REACH. Halogen-free FR compounds have been developed as alternatives. So far, not many biobased FR have made it to the market and are being applied in the textile sector, leaving great opportunities since biobased products are experiencing a renaissance. In this study, renewable FR based on sorbitol and isosorbide were synthesised. The reaction was performed in the melt. The resulting biobased FR were characterised via FT-IR, thermogravimetric analysis (TGA) and X-ray fluorescence (XRF). Cotton fabrics functionalized with the developed biobased FR passed ISO 15025 FR test. After washing, the FR properties of the fabrics decreased (longer afterflame and afterglow time) but still complied with ISO 15025, indicating the biobased FR were semi-permanent. The amount of residue of modified sorbitol and isosorbide measured at 600 °C in air was 31% and 27%, respectively. Cotton treated with biobased modified FR showed no ignition during cone calorimetry experiments, indicating a flame retardancy. Furthermore, a charring of the FR containing samples was observed by means of cone calorimetry and TGA measurements.

The aspects of fire retardation in some phosphorus-modified polymethyl methacrylate (PMMA) and polystyrene (PSt) polymers are reported in the present paper. Both additive and reactive strategies were employed to obtain the desired level of loading of the phosphorus-bearing compound/moiety (2 wt.% of P in each case). Test samples were obtained using bulk polymerization. The modifying compounds contained the P-atom in various chemical environments, as well as in an oxidation state of either III or V. With a view to gain an understanding of the chemical constitution of the gaseous products formed from the thermal decomposition of liquid additives/reactives, these materials were subjected to GC/MS analysis, whereas the decomposition of solid additives was detailed using the pyrolysis-GC/MS technique. Other investigations included the use of: Inductively-coupled Plasma/Optical Emission Spectroscopy (ICP/OES), solid-state NMR and FT-IR spectroscopy. In the case of PMMA-based systems, it was found that the modifying phosphonate ester function, upon thermal cracking, produced ‘phosphorus’ acid species which initiated the charring process. In the case of solid additives, it is more likely that the resultant phosphorus- and/or oxygenated phosphorus-containing volatiles acted as flame inhibitors in the gaseous phase. With the PSt-based systems, a probable process involving the phosphorylation of the phenyl groups leading to crosslinking and char formation is feasible.

Lignin-based flame retardants represent great promising next-generation flame retardants due to their sustainability, unique aromatic structure, and high charring capability. However, their applications are still limited by the compatibility, processability, and efficiency of flame retardancy. Here, a green functional lignin-based nanofiller (lignin-diethylenetriamine/red phosphorus nanoparticles, Lignin-N-P NPs) was prepared by the chemical modification and co-precipitation. After blending with the commercial acrylonitrile butadiene styrene copolymers (ABS), the physical, chemical, and flame retardant properties of the blends reveal that Lignin-N-P NPs/ABS blend has acceptable processability, mechanical properties, and significantly improved thermal stability and fire performance. Its values of peak heat release rate and total heat released per unit area were significantly dropped 67.8% and 77.5%, respectively. This study will initiate a new design for not only flame retardants but also lignin-based materials.

In this study, a flame retardant agent, called PEDSCD, is synthesized through a polycondensation reaction. PEDSCD is a chemically expanded phosphorus-containing flame retardant, which is introduced in epoxy resin (EP) to improve its flame retardancy. The molecular structure and thermal stability of PEDSCD are characterized by nuclear magnetic resonance, Fourier transform infrared spectroscopy, and thermogravimetric analysis, and EP/PEDSCD composites are investigated in detail. EP/PEDSCD exhibits good stability and flame retardancy. These properties are attributed to the triazine structure introduced into the flame retardant system. The triazine structure starts to decompose at a lower temperature and also reacts with the phosphorus element to form P[double bond, length as m-dash]N-, which increases the viscosity of the melt. This inhibits the generation of smoke and reduces the peak of heat release. PEDSCD shows good thermal stability and low flammability. Further, the weight loss from 500 to 800 °C is only 16 wt%, and the residual mass at 800 °C is 32 wt%. With the addition of PEDSCD, the flame retardant quality of the EP/PEDSCD composites is gradually enhanced, and the carbon residue becomes denser, which isolates the heat transfer and inhibits the volatilization of flue gas. The limited oxygen index (LOI) value of 27% and a vertical burning V-0 rating are achieved when PEDSCD is used in combination with ammonium polyphosphate (APP). The cone calorimeter test shows that the peak heat release rate is reduced by 29% and low gas content is generated, which verifies that the combination of PEDSCD and other phosphorus-containing flame retardants exhibits significantly enhanced flame-retardant properties. PEDSCD exhibits a charring and barrier effect in the condensation phase. Overall, using basic characterization and flame retardancy testing, it is proved that PEDSCD exhibits good flame retardancy when added to EP.

Fire behavior of cross-laminated timber (CLT) has been well documented in the past decade by several research organizations and universities across North America, Europe and Japan. The recent revision of ANSI/APA PRG 320 introduced two mandatory adhesive test methods to greatly reduce the potential for heat delamination. This research evaluated CLT face-bonded with adhesives that meet these new requirements, namely with respect to the resulting charring rate and potential contribution to fire growth and intensity in a compartment fire. The results suggest that CLT manufactured with an adhesive that meets the 2018 ANSI/APA PRG 320 requirements could be designed using a constant one-dimensional charring rate during a standard fire exposure. Results of room fire tests also showed that compartments made of CLT elements manufactured with non-delaminating adhesives eventually reached burn-out of the fuel content in several tests, leading to self-extinguishment., World Conference on Timber Engineering 2021, WCTE 2021, August 9-12, 2021, Santiago, Chile

The paper assesses the influence of the heat flux on spruce wood (Picea abies L.) behavior. The heat flux was performed at 15, 20, 25, and 30 kW·m−2. The fire-technical properties, such as the mass burning rate, charring thickness, charring rate, as well as the chemical composition (contents of the extractives, lignin, cellulose, holocellulose), of wood were determined. The highest burning rate of spruce wood of 0.32%·s−1 was reached at the heat flux of 30 kW·m−2. The charring rate ranged from 1.004 mm·min−1 (15 kW·m−2) to 2.016 mm·min−1 (30 kW·m−2). The proposed model of the charring process of spruce wood in time and appropriate thickness as a selected parameter is applicable in validation of the results of computer fire models in the design of fire protection of wooden buildings. The decrease in the holocellulose content mostly caused by the degradation of hemicelluloses was observed during thermal loading. The biggest decrease in hemicelluloses (24.94%) was recorded in samples loaded at 30 kW·m−2. The contents of cellulose increased due to the structural changes (carbonization and crosslinking), the content of lignin increased as well due to its higher thermal stability compared to saccharides, as well as the resulting lignin condensation.

The catalytic hydrotreatment of fast pyrolysis liquids (PL) from lignocellulosic biomass is a promising technology to improve the properties of PL. Mild hydrotreatment (< 250 °C) using a suitable catalyst allows the production of stabilized oils that have for instance potential for co-processing in existing oil refinery units. Here, we report a catalyst screening study to stabilize PL by a mild hydrotreatment using five Raney nickel “type” catalysts (Ra-Ni), more specifically a benchmark Ra-Ni, two types of Fe/Cr promoted, and two Mo-promoted ones. Experiments were performed at relatively mild hydrotreatment conditions (200 °C, initial 140 bar H2 pressure, 4 h) in a batch autoclave. Among all the Ra-Ni catalysts, the Mo promoted (A-7063) showed the highest hydro-(deoxy)genation activity, a lower extent of repolymerization (GPC), and lower charring tendency of the product oil (TGA) compared to the promoter-free and Fe/Cr promoted Ra-Ni catalysts. Analyses of the product oils showed that the oils contain a significant amount of phenolics (7.4–15.4 wt% on oil, GC x GC-FID). These findings indicate that commercially available Raney nickel “type” catalysts, and particularly the Mo promoted ones, are attractive to be used for the mild hydrotreatment of pyrolysis liquids.

Ammonium polyphosphate (APP) with different polymerization degrees were modified by a novel phosphorus-containing organosilicon compound (PCOC), and the products obtained were coded as MAPP-30 and MAPP-1000. Then they were applied to prepare flame-retardant rigid polyurethane foam (RPUF) separately. The impact of modified APP (MAPP) on the flame-retardant properties of RPUF was investigated by the limited oxygen index (LOI) test, horizontal burning test, and cone calorimeter test. The morphologies of the char residues were observed by SEM. Furthermore, the mechanical properties of RPUF composites were measured by the compressive strength test. The results showed that whether the degree of polymerization of MAPP is 30 or 1000, they both had greater charring ability and better flame-retardant properties than unmodified APP. The residual char yield of RPUF/MAPP-30 (37.3%) and RPUF/MAPP-1000 (36.5%) were both significantly higher than RPUF/APP-30 (22.8%) and RPUF/APP-1000 (24.9%). The peak heat release rate value of RPUF/MAPP-30 was 29.9% lower than that of RPUF/APP-30, and the drop of RPUF/MAPP-1000 was 50.9% compared to RPUF/APP-1000. Moreover, the total heat release of RPUF/MAPP-1000 (9.7 MJ/m2) was much lower than that of RPUF/MAPP-30 (11.3 MJ/m2). In summary, MAPP-1000 has the best flame-retardant properties among all RPUF composites. In addition, the results also showed that flame-retardant performance and the mechanical properties dramatically decreased with the increase in the addition of MAPP-1000, and the RPUF composite had the best comprehensive performance with 20% content of MAPP-1000.

Within nuclear facilities, several fires with the implication of cable trays has been reported. The fire behavior of those cable trays is unknown while inside the nuclear structures there are thousands of kilometers of electric cable trays. The main aim is to develop an experimental model based on analytic relations that can characterize the ignition and fire spreading along an electric cable tray. The first part of this thesis has been devoted to study the analytic relations at a small scale for electric cables. Experiments on a calorimeter cone were performed with the aim to determine the ignition time, then on a simple cable device for the fire spreading. In the second part an experimental study has been carried out on a new experimental device named CISCCO (Cable Ignition and Spreading under Controlled Conditions) after its qualification. Ignition time and flame spread rate have been obtained and compared to those predicted by Quintiere equations. Ignition times could be correctly estimated. Flame spread rate on PVC cable was also well predicted while some mismatches were observed with halogen free cables., Au sein des infrastructures nucléaires, un nombre non négligeable de cas d'incendies impliquant les câbles électriques des installations a été recensé. Le comportement au feu de ces chemins de câbles est peu connu or il existe plusieurs milliers de kilomètres de câbles dans ces installations. Le but de cette thèse est donc de développer et valider des relations analytiques permettant de caractériser l'inflammation et la propagation du feu d'un chemin de câbles électriques afin de les implémenter par la suite dans un code de calcul pour prédire ces phénomènes. Une première phase de la thèse est consacrée à l'étude de ces relations à petite échelle pour des câbles électriques avec retardateurs de flamme sans halogène et avec halogène. Des expérimentations ont été réalisées au cône calorimètre pour caractériser l’inflammation et sur un dispositif pour câble unique pour caractériser la propagation de flamme. Des relations ont été établies entre le comportement au feu des câbles, la nature des matériaux polymères constituant les gaines et les mécanismes de dégradation impliqués. Dans une seconde phase, des expérimentations à moyenne échelle sont réalisés à l’aide d’un nouvel appareil expérimental nommé CISCCO (Cable Ignition and Spreading under Controlled Conditions) après qualification de ce dernier. Les temps d’ignition et vitesse de propagation ont été mesurées et comparées à ceux prédits par le modèle de Quintiere. Les temps d’ignition sont correctement décrits. Les vitesses de propagation sont, quant à elles, bien simulées pour le chemin de câbles PVC tandis que des écarts sont observés pour les câbles sans halogène.

Lightweight polymeric foam is highly attractive as thermal insulation materials for energy-saving buildings but is plagued by its inherent flammability. Fire-retardant coatings are suggested as an effective means to solve this problem. However, most of the existing fire-retardant coatings suffer from poor interfacial adhesion to polymeric foam during use. In nature, snails and tree frogs exhibit strong adhesion to a variety of surfaces by interfacial hydrogen-bonding and mechanical interlocking, respectively. Inspired by their adhesion mechanisms, we herein rationally design fire-retardant polymeric coatings with phase-separated micro/nanostructuresivia/ia facile radical copolymerization of hydroxyethyl acrylate (HEA) and sodium vinylsulfonate (VS). The resultant waterborne poly(VS-ico/i-HEA) copolymers exhibit strong interfacial adhesion to rigid polyurethane (PU) foam and other substrates, better than most of the current adhesives because of the combination of interfacial hydrogen-bonding and mechanical interlocking. Besides a superhydrophobic feature, the poly(VS-ico/i-HEA)-coated PU foam can self-extinguish a flame, exhibiting a desired V-0 rating during vertical burning and low heat and smoke release due to its high charring capability, which is superior to its previous counterparts. Moreover, the foam thermal insulation is well-preserved and agrees well with theoretical calculations. This work offers a facile biomimetic strategy for creating advanced adhesive fire-retardant polymeric coatings for many flammable substrates.

The fluoride adsorption capacity of three types of bone char (BC), including cow BC (CBC), chicken BC (CKBC), and pig BC (PBC), was examined. At the optimum charring conditions (temperature and time), PBC had the highest hydroxyapatite (HAP) content (0.928 g-HAP/g-BC), while CBC had the highest specific surface area (103.11 m2/g-BC). CBC also had the maximum fluoride adsorption capacity (0.788 mg-F/g-HAP), suggesting that fluoride adsorption capacity depends more on the specific surface area of the BC than the HAP content. The adsorption data of CBC, CKBC, and PBC fit well with the pseudo-second-order model and the Langmuir isotherm. The maximum fluoride adsorption capacity of BC reached the maximum value when the solution had a pH of approximately 6.0. Lastly, the highest fluoride desorption occurred when the BCs were soaked in solutions with a pH higher than 11.0.

The increasing use of composite materials in aircraft cabins and structures poses significant challenges in order to maintain and improve the fire safety of aviation. In this work, the flammability characteristics of a commercial glass-fibre reinforced phenolic composite (GFRP) used for aircraft cabin partitions and furnishing are investigated experimentally. Thermogravimetric analysis under inert atmosphere at several heating rates provided information on the thermal decomposition process. The degradation process is modelled with one and two-step mechanisms using the Ozawa–Flynn–Wall iso-conversional method and the GPYRO numerical code which utilizes a genetic algorithm optimization scheme. The estimated activation energy and pre-exponential factor values, especially in the two-step case (77.18 and 104.69 kJ/mol and 2.60 × 106 and 3.19 × 106 min−1 for the first and the second step respectively), recover reasonably well the conversion degree and its derivative. Tests with a cone calorimeter (CC), performed at different incident heat fluxes, provided information on the reaction to fire characteristics of the material and the influence of the heat flux on the combustion process. In general, combustion proceeds in two stages, flaming and smoldering combustion. The CC results assisted by scanning electron microscopy photos provide information on the charring characteristics of the material. The critical heat flux for ignition and the corresponding ignition temperature are estimated, correlating heat fluxes with time to ignition. Thermally thin and thick models are considered, as well as a modified technique bridging the gap between these limit cases and therefore valid for thermally thin and thick but also intermediate conditions (more pertinent in the present case). The results for this latter approach are $$\dot{q}^{\prime\prime}_{ig,cr}$$ ~ 20 kW/m2 and Tig = 469°C, providing also complementing information on thermophysical properties, such as thermal diffusivity, α = 1.23 × 10−7 m2/s, thermal conductivity, k = 0.325 W/(m K) and specific heat capacity, c = 1.330 kJ/(kg K). This work provides information on the reaction to fire characteristics of GFRP, but also on physical and flammability properties in a form suitable to be used in numerical codes, for the prediction of fire and evacuation scenarios. The influence of the reinforcement structure on the fire behaviour of the composite is also illustrated and discussed.

Engineered wood products (EWPs) are a group of materials having a very similar chemical composition but having different and non-uniform thermo-physical properties throughout their thickness. Such materials present a significant challenge from the pyrolysis modelling point of view. The main focus of the paper is to study and compare the differences between six EWPs—oriented strand board (OSB), plywood, particle board (PB), low-density (LDF), medium-density (MDF) and high-density (HDF) fibreboard—in terms of their pyrolysis and burning behaviour. Vertical density profiles (VDPs), thermal degradation behaviour, and burning behaviour were studied and compared. There is a considerable need for a consistent and systematic approach in estimating pyrolysis model complexity and model input parameters. A systematic method to determine the minimum level of the EWPs decomposition model complexity to reproduce the thermal degradation behaviour as measured using thermogravimetric analysis and using the set of parallel reactions was applied. EWPs were found to have similar thermal decomposition onset and range. Maximal decomposition rates were within 25%. OSB, PB, LDF and HDF decomposition can be modelled using three-step parallel reactions scheme, MDF using four parallel reactions. A set of parallel reactions cannot describe the thermal degradation behaviour of plywood. Cone calorimeter tests at heat flux levels of 20 kW/m2, 50 kW/m2 and $$80\, \hbox {kW}/\hbox {m}^{2}$$ revealed that influence of the different thermo-physical properties on time to ignition and time to peak heat release rate (HRR) is not significant except LDF and HDF due to their very different density. Peak HRR varies between EWPs, which is attributed primarily to charring and different thermo-physical properties of the EWPs char. EWPs gas phase combustion parameters for the fire models were derived.

The porous medium with a carbide layer and the mechanical denudation accompanied by the reaction process make the study of an ablation model more complex. The chemical vapor deposition and thermal ...

In this paper, the thermal response of orthotropic carbon–carbon is studied. In the first step, non-charring materials ablation is implemented into a finite volume solver. Carbon–carbon ablative thermal behavior is studied under a time-dependent heat flux. The equilibrium surface thermochemistry model of carbon ablation in air including the diffusion and sublimation along with energy source term, heated wall recession and material properties are all applied in FLUENT 6.3 solver via user-defined functions. Stagnation point temperature, recession and net heat flux for the isotropic case are compared with the published one-dimensional finite difference results. Subsequently, the effects of orthotropic conductivity of the material on surface temperature, ablation mass flux, recession rate of the heated wall and the temperature distribution through the material are described. Results indicate that higher surface temperature and ablation mass flux as well as lower interior temperatures are achieved by the orthotropic material response, compared to the isotropic one. The same conclusion can be made by increasing the ratio of “in-plane” to “through-the-thickness” conductivities. In brief, this work presents a methodology for modeling two- and three-dimensional non-charring material ablation within FLUENT solver to study the thermal response of an anisotropic ablator, sharp geometries and metal–insulator interface where a classic one-dimensional approach is inaccurate.

Bismuth oxychloride nanosheet modified with silane coupling agent (KH570-BiOCl) was prepared by a facile liquid-phase method and used as a green inorganic flame retardant to replace Sb2O3, a conventional flame retardant of flexible poly (vinyl chloride), PVC in short. The as-prepared nanosheet was characterized by X-ray diffraction, scanning electron microscopy and Fourier transform infrared spectrometry. Its effect on the flame-retardant performance of PVC was investigated by cone calorimetry test (CCT) in association with thermogravimetric analysis (TGA) as well as condensed-phase and gas-phase analyses by Raman spectroscopy and thermogravimetric–infrared spectrometry, respectively. TGA and CCT results indicated that, as a potential flame retardant of PVC, the as-prepared KH570-BiOCl nanosheet with a thickness of about 30–40 nm had good charring ability and could effectively improve the flame retardancy of PVC. Particularly, the PVC-matrix composite with 3% (mass fraction) of KH570-BiOCl nanosheet exhibited 18.65% of char residue as well as significantly reduced the peak heat release rate (45.3%), peak smoke production rate (55.3%) and total smoke production (31.4%). This is because the BiOCl nanosheet could act as a physical barrier to prevent the heat transfer as well as the release and diffusion of the decomposed products of PVC matrix, while it also could catalyze and promote the formation of char layer in the manner similar to that of gaseous phase of Sb2O3. Thus, the KH570-BiOCl nanosheet showed great potential to replace Sb2O3 and provided the promising manner to develop an environmental friendly PVC composite.

Wood flour (WF) filled polymer composites are widely used in our daily life. Unfortunately, a wick effect of WF during burning seriously deteriorates the flame retardancy of wood-plastic composites. Traditional flame retardants cannot efficiently restrict the wick effect of WF due to their random distribution. In this work, amino glycerin decorated ammonium polyphosphate (APD-APP) was well designed and prepared through an ion exchange reaction to tailor the dispersion of flame retardant in WF-filled polymer composites. When the APD-APP was incorporated into the WF/polypropylene composite (WPC), it showed significantly different distribution compared to that of APP and mainly accumulated at the surface of WF, and then resulted in the formation of core-shell WF@APD-APP. More importantly, the flame retardancy of WPC/APD-APP is remarkably superior to that of WPC/APP. In vertical burning test, 25.0 wt% of APD-APP upgraded the UL-94 rating and limiting oxygen index (LOI) of WPC from no rating and 19.0% to the corresponding V-0 rating and 29.0%. Moreover, the melt dripping of WPC was completely eliminated by APD-APP. In the combustion test, the peak of heat release rate and total smoke production for WPC were respectively decreased by 70.0% and 76.6% in the presence of 30.0 wt% of APD-APP. In addition, mechanical properties of WPC/APD-APP are also superior to that of WPC/APP. The mechanism for the excellent flame retardancy of WPC/APD-APP revealed that the formed core-shell WF@APD-APP affected a residual network through the intergrowth charring of APD-APP and WF during thermally decomposing, and then the wick effect of WF was significantly weakened. Finally, the flame retardancy of WPC/APD-APP was enhanced through typical intumescent flame-retarding action via simultaneous interfacial and bulk charring.

Endowing rigid polyurethane foam (PUF) with a good fire-retardancy is essential for improving fire safety. Chemical improvement in fire-retardancy by using reactive-type flame retardants is better because of the disadvantages of traditional additive-type flame retardants. A reactive flame retardant tri-glycidyl phosphate (POG), which was synthesized by using phosphorus oxychloride and glycidol, was bound to the cross-linked network structure of PUF. The effects of POG on the physical-mechanical properties, morphology, thermal stability and fire-retardancy of PUF system were systematically investigated. Research results showed that POG resulted in an improvement in the thermal insulation ability and a slight decrease in the compressive strength of PUF. Furthermore, thermogravimetric analysis certified that the thermal stability and the char yield at 700 °C of PUF were significantly enhanced by incorporating POG. The limiting oxygen index increased to 22.3% with rising loading of POG. Moreover, a 30.2% decline in total heat release was achieved, the time to flameout was significantly shortened. Additionally, the vertical burning test illustrated that POG effectively limited the spread of flame and eliminated melt dripping. Further study confirmed that the fire-retardancy of PUF was significantly improved by inhibiting flame in the gas phase and charring in condensed phase.

The recent development of microwave radiation technology has increased the application possibilities of waste tobacco stems (WTSs). In this study, the morphology and microwave absorption properties of tobacco stem materials as well as the pyrolysis of the resultant biomass (BMTS) were studied via thermogravimetry–differential scanning calorimetry (TG-DSC), scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP), and a vector network analysis (VNA). The results show that the BMTS pyrolysis involves four stages in air: dehydration, heat transfer, pyrolysis, and carbonisation, and it involves three stages in N2: moisture evaporation, de-volatilization, and charring. The microwave-assisted expansion of WTSs can improve the pore diameter and total porosity of the expanded tobacco stems (ETSs) and BMTS. The latter is a macroporous material with a total porosity of 78.2% and a probable pore size of 29.5 μm. Its pore size distribution ranges from 10.7 nm to 227 μm. The microwave absorption properties of the WTSs are affected by the moisture content, bulk density, and grain size; the properties can be enhanced by decreasing the grain size and increasing the moisture content and bulk density within the experimental range. The 3 dB bandwidth and amplitude vary by 0.45 MHz and − 0.406 dB per 1% increase in the moisture content of the materials, respectively. Our results demonstrate that tobacco stem materials with different moisture contents and grain sizes should be classified before the expansion or re-drying steps to ensure heating uniformity and product quality during the microwave radiation treatment.

A new P/N/Si/S-containing mononickel complex NiS, which can be regarded as a rare type of the metal-based intumescent flame retardant, has been prepared through the condensation reaction of precursor NiCl with 1, 2-ethanedithiol in the presence of Methylamine as acid-binding agent. Its molecular structure is well characterized by elemental analysis, infrared (IR) and nuclear magnetic resonance (NMR) spectroscopies. The target flame retardant NiS has been successfully applied to cotton fabrics through a pad-dry-cure method. Thermal degradation properties of neat and treated cotton fabrics with 10.7 wt% NiS are studied by thermogravimetric analysis (TGA). Flammability behaviors of neat and treated cotton with 10.7 wt% NiS are evaluated using vertical burning test, limiting oxygen index (LOI) and microscale combustion calorimeter (MCC). Meanwhile, to further investigate the flame retardancy of NiS for cotton fabrics, the char layers of neat and treated samples after combustion are analyzed by SEM image and Raman spectroscopy. As a result, the improved thermal and flammability performance for cotton fabrics by introduction of NiS might be due to the metal-assisted catalytic charring effect of NiS on the formation of the compact char layer and the release of the flammable gas.

The main objective of this work is to compare the fire resistance between wood-steel-wood (W-S-W) and wood-wood-wood (W-W-W) connections, both joined by steel dowel fasteners, in double shear. The analytical and design procedures follow simplified equations presented in Eurocode 5, part 1-1 and 1-2. A computational methodology, based on finite element method, was also implemented to produce two dimensional thermal simulations, which permits to verify the heating effect through the dowels fasteners or steel elements through the connection in study. Different cross-sections will be identified, considered as the most relevant parts, to compare the temperature distribution in the studied connections. According to the fire exposure, a thermal and transient effect will happen and a char-layer appearing in the exposure side of the connections. The measured quantity of the charred area permits to identify the lost structural material in the studied cross-sections. The charring rate will calculate and compared with the constant value proposed by the Eurocode 5, part 1-2. There are typical values for the charring rate of wood between 0.5-1.0mm/min according to Eurocode 5, part 1-2. However, as a general conclusion and additional information to help designers and professionals, the number of fasteners increases with the applied load, lower dowels diameters have higher effect in the number of fasteners, at fire exposure the steel fasteners bring the heat to inside the connections, and different wood densities affect the thermal behaviour and the charring rate evolution. The charring rate permits to quantify the lost layer thickness and the fire resistance of the connection, dependent on the chosen material density.

To better understand thermal behaviors, combustion kinetic characteristics and dynamic releasing processes of gaseous products of four components separated from asphalt binder, thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR) tests were conducted on each component at different heating rates, and both differential and integral methods were utilized to discuss their combustion kinetics characteristics, respectively. Results indicate that combustion processes of four components include the volatilization of light components in stage 1 and the combustion of charring layer in stage 2. Main mass losses of saturates and aromatics occur in stage 1, but the mass loss percentages of resins and asphaltenes in the two stages are almost equal. Thermal stability of four components is successively increased from saturates to aromatics, resins and asphaltenes. Also, there is a lag of combustion process due to more incomplete decomposition of each component at a higher heating rate. Temperature range of each combustion stage is widened as the heating rate is raised. Thermal decompositions of resins and asphaltenes are less affected by the heating rate than those of saturates and aromatics. Additionally, activation energy in each component combustion stage is calculated and collated by differential and integral methods, which are suitable to discuss combustion kinetics characteristics of four components and evaluate their thermal stability. Finally, the release rate and amount of gaseous products are increased at a higher heating rate. Combustion properties of asphalt materials are further understood at the component level.

To explore the more effective non-halogen flame retardants in epoxy resins, a flame retardant named ABD owning relatively short bridged bonds and a hydroxyl group was synthesized via addition reaction between acrolein and 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO). Then, ABD was applied into flame retardant epoxy resin, diglycidyl ether of bisphenol-A, cured by 4,4′-diamino-diphenylmethane. When the mass fraction of ABD in epoxy resin was only 3 wt%, the thermoset acquired a higher limited oxygen index (LOI) value 36.2% and passed UL94 V-0 rating. ABD also reduced all the values of peak of heat release rate (pk-HRR), total heat release (THR), average effective heat of combustion (av-EHC), total mass loss (TML) and average CO 2 yield, and increased the residue yield. In contrast to DOPO, ABD can impose the higher LOI value, the higher UL94 rating and the lower peak value of HRR to epoxy thermosets. Further, the results from the cone calorimeter test reveal that the better flame retardant performance of ABD was caused by quenching effect from phosphaphenanthrene groups in gas phase and the charring effect from the joint action of phosphaphenanthrene group and hydroxyl group in condensed phase simultaneously. The excellent flame retardant performance of ABD is from its higher phosphorus contents and its special hydroxyl group.