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This research aims to improve the flame-retardant properties of wood–plastic composites with different recycled plastics. Acrylonitrile butadiene styrene (ABS) and polyvinyl chloride (PVC), flame-retardant materials, and recycled polypropylene (PP) were used as matrix in this research. Recycled ethylene propylene diene monomer (EPDM) with flame-retardant properties was also added to mix with rubberwood flour (RWF) to improve mechanical properties. The rubberwood flour, coupling agent (MAPP), and lubricant are fixed at 44.5%, 4%, and 1%, respectively, whereas recycled plastics and EPDM rubber contents are in the range of 30.5–50.5% and 0–20%, respectively. The composite materials were manufactured into panels using a twin-screw extruder and hot press machine. The experimental results were statistically analyzed by analysis of variance (two-way ANOVA) at a 95% confidence level. The highest values of the mechanical parameters of wood–plastic composites reinforced with recycled polypropylene (RWF44.5PP50.5) were 15.89 MPa, 42.26 MPa, 41.79 MPa, and 0.0202 J for tensile strength, flexural strength, compression strength, and impact strength, respectively. An increasing EPDM rubber content of wood–plastic composites provided better thermal properties. The thermogravimetric analysis and differential scanning calorimetry of hybrid composites with recycled ABS (RWF44.5ABS30.5EPDM20) obtained the highest value with thermal stability in the range of 255–284 °C. For the flammability properties, the hybrid composites with high EPDM rubber content were less flammable. Recycled PVC with content of RWF44.5PVC50.5 outperformed hybrid composites reinforced made from ABS and PP in terms of UL-94 and the limiting oxygen index with values of 25.73%. [ABSTRACT FROM AUTHOR]

As one of the most effective fire prevention measures, the ultra-thin intumescent fire-retardant coating (IFRC) is widely used to coat the surface of steel structure in buildings. The aim of this work was to investigate the pyrolysis characteristics, kinetics and flame-retardant mechanism of ultra-thin IFRC for dealing with the fire hazards of steel structures. Thermogravimetric experiments were carried out at multiple heating rates. The thermogravimetric analysis results showed that the whole thermal degradation process could be divided into two stages. In Stage I, the active filler and resin released H2O and other small molecules with the mass loss of 10%. Stage II was assigned to the intramolecular and intermolecular reactions of the matrix resin, catalyst, carbon forming agent and foaming agent in the ultra-thin IFRC, which released the flame-retardant gases NH3, H2O and CO2. The initial kinetic parameters were obtained by the model-free method, and then the shuffled complex evolution (SCE) algorithm was used to optimize these proposed kinetic parameters. Moreover, the predicted pyrolysis curves based on optimized kinetic parameters were compared with experimental data, and the good agreement was achieved. Eventually, the flame-retardant mechanism in different stages was speculated, which could provide the basis and reference for the development and application of the ultra-thin IFRC. [ABSTRACT FROM AUTHOR]

OPFRs are emerging environmental pollutants with reproductive and endocrine toxicity. This study aimed to examine the association between environmental exposure to OPFRs during early pregnancy and GDM. This nested case–control study was based on a birth cohort that was constructed at a maternal and child health hospital, including 74 cases of GDM among 512 pregnant women. The OPFRs, including TBP, TBEP, TCEP, TDCPP, TMCP, TOCP, and TPHP during 10–14 weeks of pregnancy were determined using GC–MS. The association between the OPFRs and GDM was assessed using WQS and BKMR models. The levels of OPFRs were significantly elevated in GDM patients (60) compared with the controls (90). The WQS analysis showed that mixtures of the OPFRs were significantly associated with GDM (OR 1.370, 95% CI 1.036–1.810, P = 0.027), and TBP, TPHP, and TMCP were the major contributors to the mixed exposure effect. In the BKMR model, individual exposure to TBP, TPHP, and TMCP, and the interaction of TMCP with TBP and TPHP were significantly associated with GDM. Environmental exposure to OPFRs is positively associated with GDM. These findings provide evidence for the adverse effects of OPFR exposure on the health of pregnant women. [ABSTRACT FROM AUTHOR]

Fireproof coatings are the simplest, most efficient, and oldest method for protecting a wide range of flammable products, such as wood. Furthermore, surface ignition is the initial phase, so surface protection is essential to reduce fire propagation. Furthermore, delaying the spread of flames can help to save someone when a fire starts. This project synthesized flame-resistant resin starting from tetraallyloxysilane monomer as a halogen-free monomer, an intrinsic flame retardant co-curing agent. The following step synthesized polyester resin using terephthalic acid as a heat-resistant resin. Unsaturated polyester was used by bulk radical polymerization. FT-IR and 1H-NMR analysis showed the successful synthesis of the desired monomer and polymeric compound. The thermal degradation and flame retardancy of pure unsaturated polyester resin (UPE) and allyloxysilane-unsaturated polyester (AUPE) were investigated by thermogravimetric analysis (TGA/DTG/DSC). The burning test and the thermal stability of the coating layers were evaluated using standard UL 94. Physical properties of resins were evaluated using Heat Deflection Temp tests (HDT) ISO 75-A, ASTM 648, Hardness ASTM D2583, Volumetric shrinkage ASTM 3521, and Water absorption ASTM D570. The results of the tests show the successful synthesis and their flame retardant properties. [ABSTRACT FROM AUTHOR]

Polybenzoxazines (PBz) are a new type of resin belonging to the category of phenolic resins. As polybenzoxazines are addition-curable polymers, this obviates many of the shortcomings associated with conventional phenolic resins while endowing them with excellent thermal, physical, and thermo-physical properties and surpass the features of many conventional and state-of-the-art polymers. They even possess excellent design flexibility. In this study, a benzoxazine monomer was successfully synthesized from eugenol (Eu), ethylenediamine, and paraformaldehyde utilizing a solventless approach. The synthesized benzoxazine resin was characterized for its structural elucidation via FTIR, 1H, and 13C NMR spectroscopy and was used for crosslinking a petroleum-based epoxy and a gallic acid-based epoxy. The effects of the presence of benzoxazine on the thermal and flame retardant properties of the films were evaluated using TGA and DSC analysis and the LOI and UL 94 tests, respectively. It was found that the benzoxazine in the epoxy systems led to an increase in thermal stability and flame retardancy. The gallic acid-based epoxy system showed better thermal and flame retardant properties compared to the petroleum-based epoxy system, thus showing potential to replace the petroleum-based epoxy for high-performance applications. [ABSTRACT FROM AUTHOR]

Highlights: An innovative class of versatile form-stable composite phase change materials (CPCMs) was fruitfully exploited, featuring MXene/phytic acid hybrid depositing on non-carbonized wood as a robust support. The wood-based CPCMs showcase enhanced thermal conductivity of 0.82 W m−1 K−1 (4.6 times than polyethylene glycol) as well as high latent heat of 135.5 kJ kg−1 (91.5% encapsulation) with thermal durability and stability throughout at least 200 heating and cooling cycles. The wood-based CPCMs have good solar-thermal-electricity conversion, flame-retardant, and electromagnetic shielding properties. Phase change materials (PCMs) offer a promising solution to address the challenges posed by intermittency and fluctuations in solar thermal utilization. However, for organic solid–liquid PCMs, issues such as leakage, low thermal conductivity, lack of efficient solar-thermal media, and flammability have constrained their broad applications. Herein, we present an innovative class of versatile composite phase change materials (CPCMs) developed through a facile and environmentally friendly synthesis approach, leveraging the inherent anisotropy and unidirectional porosity of wood aerogel (nanowood) to support polyethylene glycol (PEG). The wood modification process involves the incorporation of phytic acid (PA) and MXene hybrid structure through an evaporation-induced assembly method, which could impart non-leaking PEG filling while concurrently facilitating thermal conduction, light absorption, and flame-retardant. Consequently, the as-prepared wood-based CPCMs showcase enhanced thermal conductivity (0.82 W m−1 K−1, about 4.6 times than PEG) as well as high latent heat of 135.5 kJ kg−1 (91.5% encapsulation) with thermal durability and stability throughout at least 200 heating and cooling cycles, featuring dramatic solar-thermal conversion efficiency up to 98.58%. In addition, with the synergistic effect of phytic acid and MXene, the flame-retardant performance of the CPCMs has been significantly enhanced, showing a self-extinguishing behavior. Moreover, the excellent electromagnetic shielding of 44.45 dB was endowed to the CPCMs, relieving contemporary health hazards associated with electromagnetic waves. Overall, we capitalize on the exquisite wood cell structure with unidirectional transport inherent in the development of multifunctional CPCMs, showcasing the operational principle through a proof-of-concept prototype system. [ABSTRACT FROM AUTHOR]

An iron-based metal–organic framework, MIL-53(Fe), was synthesized and added as a synergist to high-density polyethylene (HDPE), and its flame-retardant effect with aluminum diethyl hypophosphite (ADP) and aluminum hypophosphite (AHP) in HDPE was investigated to further improve the flame-retardant efficiency. FTIR results showed that the ADP, AHP, and MIL-53(Fe) were successfully incorporated into the HDPE. The LOI of HDPE-3 and HDPE-7 with 0.75 mass% MIL-53(Fe) was 48.9% and 34.8% higher than that of the pure sample. The combustion grades reached V-0 and V-1. HDPE/MIL-53(Fe)/ADP exhibited more superior flame-retardant properties than HDPE/MIL-53(Fe)/AHP. A synergistic effect between ADP and both AHP and MIL-53(Fe) changes the decomposition process of HDPE. In addition, the FGI value of the composites decreased after the addition of MIL-53(Fe). MIL-53(Fe) enhances the thermal stability of HDPE composites, and improves the quality of the char residue. Experimental results show that MIL-53(Fe) can be used as a flame retardant and is a novel material in polymer flame-retardant research. The new synthetic material shown here may contribute to environmental safety. [ABSTRACT FROM AUTHOR]

Wood is a primary building tool for ancient buildings and structures, but for those that survive to date, naturally aged wood may pose a noteworthy fire hazard. There are potential risks to health, safety, and substantial cultural loss if fire risks in such buildings are not mitigated. We obtained several samples of aged wood commonly used in ancient structures (elm, pine, and aspen), and compared the kinetic and thermal characteristics to fresh wood examples to determine potential methods of enhancing safety. Differential scanning calorimetry was used to establish the heat release characteristics of the fresh and aged samples, and the characteristics of the thermal reaction stages were characterized using the temperature range and heat release laws for each reaction stage. The heat release characteristics during combustion were investigated for different heating rates, and the influence of aging on temperature change and heat release rate characteristics during different exothermic stages was assessed. Finally, using heat flow data, the apparent activation energy (AAE) of the samples and their distributions during different exothermic stages were calculated and analyzed via the Friedman differential iso-conversion method. Results showed that the exothermic energy of the aged samples was higher than that of the fresh samples, indicating that aging does impact the thermal reaction process. The aged samples in this study had a greater heat diffusion capacity, transmitted more heat, were more susceptible to burning (by spreading that heat), and generally posed a greater fire hazard. During the rapid exothermic phase, the AAE of aged wood increased as the reaction progressed, and exhibited lower AAE with a greater sensitivity to fire than fresh samples. A sound linear relationship between pre-exponential factor and AAE and the kinetic compensation effect was obvious. This study provided a rudimentary theoretical basis for the prevention of fires in timber-framed ancient buildings. [ABSTRACT FROM AUTHOR]

Over the past few decades, the development of highly efficient phosphorus-based flame retardants has become one of the research focuses in the field of halogen-free flame-retardant polymer technology. In this work, three kinds of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO)-based derivatives were synthesized through integrating multiple phosphorous oxidation states into one molecular structure. The influence of DOPO-based derivatives on the thermal decomposition and flame-retardant properties of EP composites were investigated. DOPO-based derivatives promoted the slightly earlier decomposition of the epoxy matrix, resulting in better thermal stability at high temperatures and higher char yield. The unmodified EP showed a LOI value of 27.0% and no UL-94 rating, while all the EP composites containing 2 wt.% DOPO-based derivatives passed the UL-94 V-0 rating and achieved a LOI value of higher than 30.0%. Among the three DOPO-based derivatives, TDCA-DOPO-2 behaved the best flame-retardant efficiency owing to the highest synergistic effect. Specifically, the peak of heat release rate, total heat release and average effective heat combustion (av-EHC) of EP/TDCA-DOPO-2 was 62.0%, 54.2% and 39.9% lower than those of the unmodified EP, respectively. The high flame-retardant efficiency of DOPO-based derivatives was ascribed to the synergism between the barrier effect in the condensed phase (proved by the high yield and stability of char residues) and the flame inhibition effect in the gaseous phase (proved by the decreased av-EHC values). [ABSTRACT FROM AUTHOR]

High flame retardancy, satisfactory mechanical properties are crucial for polymeric composites employed in fields with safety requirements. Inorganic fillers can effectively regulate the structure and composition of polymeric materials and have become an effective strategy for fabricating high-performance polymeric composites. Herein, aluminum phosphate–coated sepiolite (Sep@AlPO4) fillers are fabricated as a multifunctional additive to modify polyethylene oxide (PEO), PEO nanocomposites were prepared via incorporation of Sep@AlPO4 and phenethyl-bridged 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) derivative (DiDOPO) in the PEO matrix, and the synergistic effects between Sep and AlPO4 are discussed. The results reveal that Sep@AlPO4 could simultaneously enhance the flame retardancy and strengthen the mechanical properties of PEO/DiDOPO. Additionally, Sep@AlPO4 could increase the viscosity, storage modulus, and loss modulus of the composites. This study provides an effective strategy for fabricating enhanced flame retardants to improve the performance of polymers. [ABSTRACT FROM AUTHOR]

This study is the first part of a larger investigation into the fire behaviour of green façades. In this study, the currently known international research status on this topic is presented and discussed. In addition, the flammability of green façades is investigated through 43 fire tests on a medium scale according to the SBI (Single Burning Item) test method EN 13823. The focus of the investigation was placed on climbing plants. A total of 25 different plant species were investigated. A comparison of the heat release rate of all the investigated vital plants shows similar behaviour. In the course of exposure, there are short peaks in the heat release rate. These peaks are "flare-ups" that occur when parts of the plants dry out due to exposure to the flame and then ignite. The plant species itself had no substantial influence on fire behaviour. Horizontal fire spread occurred to a very limited extent within the investigations of vital plants. They were self-extinguishing. The significant factor in the assessment of flammability is the moisture content of the plants. With dried plants, an abrupt heat release occurs at the beginning. Dried-out plants, as well as unmaintained plants with a high content of deadwood, represent the most critical case. [ABSTRACT FROM AUTHOR]

Fire accidents are more likely to occur in tunnels with different curves, aspect ratios, and slopes due to the land's geographical characteristics. A three-dimensional computational fluid dynamics code with curvilinear grids fitted to the body was used to simulate a variety of fire locations releasing heat at a rate of 5 MW–60 MW in a tunnel with a turning radius of 100 m–1500 m, an aspect ratio of 0.5–2, and a slope between – 10% and 10%. Using the Design of Experiments (DOE) method coupled with numerical simulations, 32 3D numerical models were constructed and a second-order critical velocity model was generated. Analysis of critical velocity was performed based on Response Surface Methodology (RSM) and multifactor curve plots were drawn for effective parameters. The results showed that the critical velocity was proportional to one-third power of the heat release rate. It was also observed that the critical velocity increased gradually as the fire source moved from the tunnel's center to its walls. Furthermore, the critical velocity decreased with increasing the aspect ratio. Results showed that the critical velocity increased with increasing the tunnel turning radius. Moreover, tunnels with negative slopes have a higher critical velocity than horizontal tunnels without slopes. Finally, by defining the parameters in non-dimensional form, a new modified form was derived for critical velocity calculation (R2 = 0.98). A critical velocity of 1.24 m/s–5.21 m/s was calculated based on five parameter values in this study. Furthermore, other straight and curved tunnel models confirmed the formula's predictions. [ABSTRACT FROM AUTHOR]

Stainless steels are used in a wide range of complex environments due to their excellent corrosion resistance. Multiphase stainless steels can offer an excellent combination of strength, toughness and corrosion resistance due to the coexistence of different microstructures. The microstructure and mechanical properties of a novel cast multiphase stainless steel, composed of martensite, ferrite, and austenite, were investigated following appropriate heat treatment processes: solution treatment at 1,050 °C for 0.5 h followed by water quenching to room temperature, and aging treatment at 500 °C for 4 h followed by water quenching to room temperature. Results show reversed austenite is formed by diffusion of Ni element during aging process, and the enrichment of Ni atoms directly determines the mechanical stability of austenite. The austenite with a lower Ni content undergoes a martensitic transformation during plastic deformation. The tensile strength of the specimen exceeds 1,100 MPa and the elongation exceeds 24% after solid solution, and further increases to 1,247 MPa and 25% after aging treatment. This enhancement is due to the TRIP effect of austenite and the precipitation of the nanoscale G-phase pinning dislocations in ferrite and martensite. [ABSTRACT FROM AUTHOR]

Polymeric thermal insulation materials, especially polyurethane foams (PUF), are widely used in buildings to diminish the energy penalty but highly flammable. To reduce the flammability and smoke release of polyurethane foams without sacrificing the inherent properties, we report an efficient strategy involving pulsed chemical vapor deposition (Pulsed-CVD) and spray atomization to generate a phosphorous/SiO2 nanolayer with a thickness below 200 nm on polydopamine modified rigid polyurethane foams. Due to the unique multilayers structure, the resultant composites showed an extra-ordinary thermal conductivity of 31.9 mW m−1 K−1 and enhanced compressive strength of 42%. Notably, the surface-treated PUF was hard to ignite in vertical test and had a very high limited oxygen index (LOI) value of 34.3%. Cone calorimetry (CC) results revealed that the total heat release (THR) and the total smoke release (TSR) were reduced by 32.9% and 64.3%, respectively. And the close-cell char structure was perfectly retained after CC test. The mechanism research suggested that silica and phosphorus promoted char formation, limited heat release and thermal degradation during combustion. These results indicate the strategy with a mild process has potential for industrialization with superior fire safety and structure stability in polymeric insulation materials. The polydopamine (PDA)-coated commercial polyurethane foam was treated through the pulsed-CVD and spray atomization strategy, the surface was decorated with flame retardant layers, and the flame and fumes were efficiently suppressed by instant char-forming and dense surface carbon barrier without sacrificing its inherent properties. [ABSTRACT FROM AUTHOR]

It is imperative to develop efficient flame retardants to solve the issues of high heat and smoke release for epoxy resin (EP) polymeric materials plagued over time. Hence, a phosphorus–nitrogen modified Ti3C2Tx MXene nanohybrids (MXene@MPA) were synthesized by in situ assembly melamine phytate macromolecules (MPA) to boost the fire hazards of EP composites. The introduction of MPA improved the dispersion of MXene in epoxy matrix, contributing to the improved thermal stability and flame-retardant properties for EP composites. With the addition of 2 mass% MXene@MPA, EP composites achieved the decreased maximum mass loss rate (MLRmax) by 41.8%, indicating the enhanced thermal properties. Also, the peak heat release rate (PHRR) and peak smoke production rate (PSPR) of EP-MXene@MPA composites were down by 27.9% and 43.6% compared to pure EP, respectively, accompanied by significantly increased char production. The synergistic effects between MPA and MXene contributed to the elevated fire safety of EP-MXene@MPA composites: the catalytic charring of transition metals and phosphorus-containing acid and the barrier effect of MXene nanosheets, as well as the quenching effects of phosphorus–oxygen free radicals and dilution of nitrogen-containing inert gases due to the decomposition of MPA. The multiple hybridization route provided a reference for the development of efficient MXene-based flame retardants. [ABSTRACT FROM AUTHOR]

In this manuscript, the UiO-66-NH2(Zr) (MOFs) was adopted to modify ammonium polyphosphate (APP), and the novel synergistic integrated flame retardant system (APP@MOFs) was formed. The flame retardants were incorporated to the thermoplastic polyurethanes (TPU) matrix, and the effects of APP@MOFs on reducing flammability of thermoplastic polyurethanes were compared and investigated. The results show that the flame retardant and smoke suppression performances of TPU/APP@MOFs composites are improved significantly. The pHRR, THR, SPR, TSP, YCO, and YCO2 of TPU/APP@MOFs composites decreased by 75.76%, 86.19%, 69.74%, 86.34%, 57.14%, and 76.37% in comparison with pure TPU. Furthermore, the char residues increased from 0.11 (pure TPU) to 32.3% (TPU/APP@MOFs composites). Generally, the APP@MOFs have great effect on improving the flame retardant and smoke suppression performances of TPU due to the catalytic carbonization and dilution effects of APP, the synergistic and catalysis effects of MOFs. Through the char structure analysis, the mechanism of the TPU/APP@MOFs composites during the combustion processes was also investigated and proposed. [ABSTRACT FROM AUTHOR]

Organophosphate flame retardants (OPFRs) are high-production volume chemicals widely present in environmental compartments. The presence of water-soluble OPFRs (tri-n-butyl phosphate (TnBP), tris(2-butoxyethyl) phosphate (TBEP), tris(2-chloroethyl) phosphate (TCEP), tris(2-chloroisopropyl) phosphate (TCPP), and triethyl phosphate (TEP)) in water compartments evidences the struggle of conventional wastewater treatment plants (WWTPs) to effectively eliminate these toxic compounds. This study reports for the first time the use of white-rot fungi as a promising alternative for the removal of these OPFRs. To accomplish this, a simple and cost-efficient quantification method for rapid monitoring of these contaminants' concentrations by GC–MS while accounting for matrix effects was developed. The method proved to be valid and reliable for all the tested parameters. Sample stability was examined under various storage conditions, showing the original samples to be stable after 60 days of freezing, while post-extraction storage techniques were also effective. Finally, a screening of fungal degraders while assessing the influence of the glucose regime on OPFR removal was performed. Longer chain organophosphate flame retardants, TBP and TBEP, could be easily and completely removed by the fungus Ganoderma lucidum after only 4 days. This fungus also stood out as the sole organism capable of partially degrading TCEP (35% removal). The other chlorinated compound, TCPP, was more easily degraded and 70% of its main isomer was removed by T. versicolor. However, chlorinated compounds were only partially degraded under nutrient-limiting conditions. TEP was either not degraded or poorly degraded, and it is likely that it is a transformation product from another OPFR's degradation. These results suggest that degradation of chlorinated compounds is dependent on the concentration of the main carbon source and that more polar OPFRs are less susceptible to degradation, given that they are less accessible to radical removal by fungi. Overall, the findings of the present study pave the way for further planned research and a potential application for the degradation of these contaminants in real wastewaters. [ABSTRACT FROM AUTHOR]

The inherent flammability of polymeric materials poses a potential threat to life and the environment. From a perspective of material renewability and environmental concern, some phosphorus-rich biomass compounds have been considered as effective replacements for conventional intumescent-based flame retardants. In this work, with the aim of suppressing the potential fire hazard of highly flammable polypropylene in a sustainable strategy, a green and facile method was proposed to synthesize ZIF-67 and further used to synergistically improve the performance of phytic acid-based intumescent flame retardants. Diverging from conventional solvothermal synthesis strategies, ZIF-67 was directly prepared with polymer matrix via a solvent-free reactive extrusion method with a notable space time yield. The reaction-to-fire properties were comprehensively investigated under forced combustion bench-scale fire conditions using a cone calorimeter with an external heat flux of 50 kW m−2. It was found that flame retardancy behaviors remain competitive when replacing 10 mass% of expandable graphite with phytic acid component. With the addition of ZIF-67, the heat release (53% reduction), smoke production (22% reduction), char structure stability (35% increment), and specific extinction area (19% reduction) behaviors were further improved due to the development of compact phospho-carbonaceous networks during combustion. Considering these excellent synergistic improvements, it provides a new potential direction to efficiently fabricate biomass-based flame retardants. [ABSTRACT FROM AUTHOR]

Thermal induced pyrolysis and the following flaming ignition of solid combustible play crucial roles in determining the occurrence of fire and the subsequent flame spread. This contribution reviews recent advances in global investigation on these two topics. Solid fuels involved in this study covering from natural materials, such as wood and biomass-based products, to artificially synthetized substances, encompassing neat polymers and functional composites, are in dense continuous form rather than piled combustibles. Most frequently utilized experimental methodologies, from microscale (TGA, DSC, STA) to bench-scale (cone calorimeter, FPA, etc.), and the corresponding analytical or numerical methods employed to extract kinetics and thermodynamics from experimental data are introduced. Meanwhile, the controlling mechanisms of piloted and auto ignitions, various types of ignition criteria, influential factors of ignition, and the modelling techniques are elaborated. Smoldering combustion, glowing ignition, and utilization of flame retardant to suppress pyrolysis or delay ignition time are mentioned in some sections, but not discussed in detail as they are beyond the focused scope. Finally, the challenging issues encountered in current stage which deserve further endeavors are indicated. [ABSTRACT FROM AUTHOR]

Unsaturated polyester resins (UPR) are broadly applied in chemical, construction, transportation and electrical fields, etc. However, UPR materials are extremely flammable. Through radiation, conduction and convection, the released heat brings serious thermal hazards to surrounding life and the environment. Meanwhile, the combustion of UPR also releases a vast of toxic pyrolysis gases and smoke, causing extremely serious non-thermal hazards, endangering life and health, reducing fire visibility and hindering escape and rescue efforts. Therefore, the flame retardant modification of UPR materials is an inevitable measure to reduce its flammability and broaden its application breadth. In this review, the flammability of UPR materials is firstly analyzed from the perspective of their compositions and structures. Meanwhile, based on the differences in preparation methods of flame retardant UPR (FR-UPR) in literature research, it is divided into additive flame retardant, intrinsic flame retardant and interfacial flame retardant methods. The relationship between the highly efficient flame retardant structures and the properties, and the gaseous-phase flame retardant and condensed-phase mechanisms in FR-UPR composites are analyzed. Compared with traditional additive flame retardants, polymeric flame retardants, nanosheet flame retardants and intrinsic flame retardant method are important directions for the future development of FR-UPR composites. In addition, the interfacial flame retardant method can effectively improve the interfacial adhesion and flame retardant properties of fiber-reinforced UPR composites, and also has application prospects. This review analyzes the current challenges faced by FR-UPR, and looks forward to its possible future development directions to guide the preparation and application of high-performance FR-UPR. [ABSTRACT FROM AUTHOR]

In this work, a novel silicone composite with low smoke, high flame retardancy, and good overall mechanical properties was prepared, and the flame-retardant mechanism of sepiolite was explored by studying the application of magnesium hydroxide/melamine/starch/sepiolite system in silicone rubber. The impact of the dosage of sepiolite on the mechanical performances of SR composites was studied. The results showed that when the dosage of sepiolite was 20 phr, the comprehensive mechanical performances of the SR composite were the best. The flame-retardant performances of the specimens were characterized by vertical combustion, the limiting oxygen index, and CCT. With the increase of sepiolite dosage, the limiting oxygen index and vertical combustion of the composites gradually enhanced, the highest peak values of HRR and SPR gradually decreased, and the values of THR and TSP gradually reduced. The SEM pictures of the char residue of CCT showed that the char layer formed by the composites with sepiolite had fewer cracks and a more robust structure. The results of the Shore OO hardness test showed that the addition of sepiolite significantly improved the strength of the char residue. TGA analysis indicated that the thermal stability of silicone rubber with sepiolite was enhanced. [ABSTRACT FROM AUTHOR]

A series of pentaerythritol derived flame retardant additives (FRs labeled FR1, FR2, FR3, and FR4) were synthesized and blended with thermoplastic polyurethane (TPU) to enhance its flame retardancy. The chemical structures of the FRs were established by FTIR, 1H, 13C and 31P NMR spectroscopy. The flammability of the TPU blends was analyzed through UL-94 vertical burning and limiting oxygen index (LOI) test. It is found that for FR4-TPU blends with 2% of phosphorus content, the LOI value reached up to 31.2%, and no melt dripping with a V-0 rating was obtained by UL-94, indicating its superior flame retardant properties. Thermogravimetric analysis (TGA) of TPU blends showed that the char yield increases from 3.9% in neat TPU to 20% with the addition of 2% of FR3 in TPU. Based on findings from scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), a possible mechanism for the flame retardant property of blends has been proposed. The improved flame retardant properties of TPU blends can be attributed to the formation of a continuous and highly entangled char. This work provides a suitable approach for synthesizing promising phosphorus-based flame retardants from readily available raw materials that can be used to enhance the flame retardancy of TPU. [ABSTRACT FROM AUTHOR]

Composites are popular in construction engineering due to their low water absorption, good chemical and corrosion resistance, lightweight, high specific strength, high specific modulus, and low thermal conductivity. The flame retardancy (FR) of composite materials has increasingly become the focus of attention in the field of construction engineering. With growing awareness of personal and property safety, a wide range of flame-retardant composites has been developed over the years through research and development. The FR of an unmodified polymer composite is not optimal, and therefore, many innovative methods for making more advanced flame-retardant materials have been developed. The aim of this review is to provide detailed literature on flame-retardant composites. The structure of this paper consists of evolution of flame-retardant materials, their manufacturing techniques, flame-retardant composites, their properties and characterization, applications, and challenges related to of FR composites. The primary focus of this review is to analyze the mechanism of fire retardancy and to summarize the preparation of flame-retardant polymer materials by adding various flame-retardant agents. [ABSTRACT FROM AUTHOR]

In this paper, melt blending process was adopted to add nanocalcined kaolin into flame-retardant grade ethylene vinyl acetate (EVA) copolymer, and thus, flame-retardant ethylene vinyl acetate nano-composite with high insulation property was prepared. The structure, mechanical properties and electrical properties of ethylene vinyl acetate composite were tested and characterized. The results of the tensile test showed that the tensile strength of the composite was reduced and the tensile modulus of the composite was increased after the addition of calcined kaolin; the results of the electrical properties test showed that the breakdown strength first increased and then decreased along with more addition of calcined kaolin, and the dielectric loss first decreased and then increased along with more addition of calcined kaolin, while the volume resistivity showed a continuous rising trend. The results of small-angle X-ray scattering test showed that the addition of calcined kaolin reduced the expansion range of EVA molecular chain, which was the major reason to cause the variation in electrical properties. [ABSTRACT FROM AUTHOR]

Amidst the global concerns in sustainable development and climate change mitigation, the demand for heat-insulating materials has been increasing in which the research objects mostly attracting attention are those from agricultural and industrial wastes due to their abundance. Aerogels have been studied for practical applications in construction because of their lightweight and super-porous properties as well as remarkable thermal insulation. An attempt has been made to create novel silica aerogel composites via in situ synthesis of rice husk ash-derived silica aerogels on the recycled polyethylene terephthalate (rPET) fiber framework and cost-effective ambient drying. Replacing expensive and toxic organosiloxane precursors with low-cost waste materials to synthesize the aerogel composites is a more economical, feasible, and user-friendly approach compared with the previous works. The fabricated aerogel composites exhibit characteristic features of aerogels, the low thermal conductivity of 0.040–0.056 W/(m·K), and a flame propagation speed of approx. 0.27 mm/s due to the adhesion of silica aerogels on the rPET fibers. The durability of the silica aerogel composites is enhanced with a structure of 4 layers of rPET fibers stacked on top of each other and alternating layers of silica aerogels, thus the as-fabricated aerogel composites show a high Young's modulus of 84.099 kPa and can withstand 695 times their weight. The as-fabricated silica aerogel composites having both thermal insulation and flame retardancy exhibit great potential in eco-friendly and energy-efficient design for construction purposes. [ABSTRACT FROM AUTHOR]

The paper describes the preparation of polyamide 6 with reduced flammability by anionic in situ polymerization of ε-caprolactam in the presence of flame retardants, a method not described in the literature. Selected inorganic and brominated organic flame retardants were characterized by thermogravimetric analysis. Polymerization tests were used to test the compatibility of flame retardants with the components of the initiation system of anionic polymerization. Based on their results, polyamide plates for the preparation of test specimens were prepared by the method of polymerization casting in a mold. The content of water-extractable portions did not exceed 3%, i.e., the conversion of monomer into polymer took place to a high degree. The presence of flame retardants both inorganic and brominated organic in the polymer matrix did not affect the thermal stability, the content of the crystalline phase and also the mechanical properties. Samples containing brominated organic flame retarders were classified as V-0 according to the UL94 methodology. [ABSTRACT FROM AUTHOR]

The durability of fire-retardant materials used for wooden structures and wood-based products can be evaluated on small cut-out samples with the so-called Lindner test, which is a standard procedure in Hungary where 1 g of hexamethylene-tetramine is burnt under the wooden specimen and the mass loss is measured. For further spatial information about the burnt part of the samples, the specimens were CT scanned after the Lindner test. The goal was to evaluate if the charred part can be properly segmented in a CT image set and if the two measurements combined are precise enough to provide charring rate data. With the segmentation of the CT image sets, the burnt volumes could be separated properly in each case even when knots were present. Spruce sample provided the most consistent results regarding the mass loss/burnt volume. This is probably due to the uneven ring spacing and other inhomogeneities in the density of oak and ash. [ABSTRACT FROM AUTHOR]

Bamboo powder has a high risk of fire and dust explosion during production, manufacturing, transportation and storage. It is of great significance to study the combustion characteristics of bamboo powder and its influencing factors for finding suitable flame retardants. So far, the relative study is more focused on bamboo rather than bamboo powder. In this paper, the combustion characteristics of bamboo powder were measured by TGA. Ignition temperature, burnout temperature, combustion rate and comprehensive combustion index were used as evaluation criteria. The influence of particle size and heating rate was quantitatively analyzed. The results showed that the ignition and burnout temperature increased with the increase in heating rate. The S value at the heating rate of 40 °C min−1 was 22 times of that at 5 °C min−1. The finer the particle size, the higher the S value, and the S value of 400-mesh bamboo powder can reach 2.0 × 10–5. The flame retardant properties of six inorganic compounds on bamboo powder were studied. According to the S value, the order of flame retardant properties at the best concentration was CaCl2 ˃ NH4H2PO4 ˃ MgCl2 ˃ Na3PO4 ˃ NH4Cl ˃ APP. Among them, 33% CaCl2 had the best flame retardancy. [ABSTRACT FROM AUTHOR]

Electrical cables are one of the main fire hazards in nuclear power plants (NPPs) and in many other industrial sectors. To assess the potential damages of the cable fires, models are required to forecast the fire spread over multiple cable trays and the resulting heat release rate. A new test device, called CISCCO, was developed to conduct flame spread experiments on a preheated horizontal cable layer to support the development and validation of the models. The characteristics of the CISCCO device are first presented before the description of four series of experiments that first investigated the temperature dependence of the flame spread velocity. The series involved a cable layer composed of either a polyvinyl chloride (PVC)-based cable, named PVC cable or a halogen free flame retardant (HFFR) poly(ethylene–vinyl acetate)/polyethylene-based cable, labelled HFFR cable. Temperature measurements performed in the solid phase (cable outer sheath) and in the gas phase (above the cable layer) allowed to assess the preheated cable layer temperature and the flame spread velocity. A first attempt of flame heat flux measurements was also conducted in this work. All series highlighted a temperature dependence of the flame spread velocity according to experimental power laws. The flame spread velocities were measured higher for the PVC cable (0 to 5.5 mm/s) than for the HFFR cable (0 to 1.5 mm/s) while the related preheated cable temperatures suitable for spreading were measured lower for the former (170 to 250°C) than for the latter (280 to 370°C). Finally, one of the four test series that used the PVC cable and implemented heat release rate measurements, revealed that the cable fire growth rate is also temperature dependent according to a power law and is linearly correlated to the flame spread velocity. [ABSTRACT FROM AUTHOR]

Poor dimensional stability, sensitivity to microorganisms, and flammability restrict the application of wood in certain areas where these properties are critical. Although furfurylation can improve the physical and mechanical properties of wood, the heat and smoke release of furfurylated wood during combustion are dramatic and need to be addressed. As a kind of halogen-free phosphorus flame retardant, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and its derivatives exhibit excellent performance in polymer composites. In this study, DOPO was dissolved in furfuryl alcohol (FA) and used to modify wood. The effect of DOPO on the thermal stability, combustion behavior, and physical and mechanical properties of furfurylated wood was investigated. The chemical structure, morphology, and char residue after combustion were also characterized. The studies show that DOPO can react with the FA polymer and is incorporated and homogeneously dispersed in the wood structure. Compared to untreated wood, furfurylated wood has a much higher heat and smoke release during combustion. The addition of DOPO remarkably reduces the heat release of furfurylated wood, and this effect increases as the amount of DOPO increases. When the amount of introduced DOPO of furfurylated wood is 7%, its total heat release is reduced by 37.4% and becomes comparable to the untreated wood. However, DOPO does not suppress smoke production effectively. DOPO improves the thermal stability of furfurylated wood by promoting char formation and inhibiting the diffusion of oxygen and the escape of pyrolysis products. The addition of DOPO has little effect on the physical and mechanical properties of furfurylated wood. The results indicate that the combination of DOPO and furfurylation could be an efficient way to prepare highly stable and fire-resistant wood materials. [ABSTRACT FROM AUTHOR]

Metal oxides were applied to cypress wood typically used as an interior building material. Combustion characteristics were evaluated focusing on the oxidation state of metal ions and char characteristics of the second stage of combustion. The burning properties of the materials were measured using a cone calorimeter (ISO 5660-1). The external heat flux was fixed at 50 kW/m2. FeO, Fe2O3, SnO and SnO2 were used as the metal oxides, and sodium silicate was mixed with increasing the flame-retardant effect. SnO2SS was 1.05 times lower than the 164.76 kW/m2 of the uncoated specimen. The other specimens increased 1.03–1.09 times. The peak smoke production rate of the wood specimens coated with flame retardant was 1.2–1.6 times lower than the uncoated specimens. SnO2SS had the lowest value and showed a synergetic effect with SS. The CO/CO2 ratio of the test specimens coated with the silicate compound was 1.6–2.3 times lower than that of the uncoated specimen. In SnO2SS, HRR2nd_peak and SPR2nd_peak decreased because the generated heat was dispersed by convection because of pores in the char. This formed a relatively hard and heat-stable char structure. [ABSTRACT FROM AUTHOR]

The existing electrolytes suffer from the uncontrolled Li+ deposition, flammability, and limited ionic conductivity problems. The gel-electrolyte is a core technology for the lithium metal batteries as they offer diverse tools for constructing unique solvent structure and suppress the uncontrolled growth of lithium dendrites. Here, a localized-anion gel-electrolyte with poly(ethyl acrylate/acrylic acid lithium) is reported to achieve a dendrite-free lithium deposition with the stable solid-electrolyte interphase. The flame-retardant triethyl phosphate are engaged in gel-electrolyte as a plasticizer with a solution casting method, which improves the safety of Li metal batteries. The TFSI− is localized by anionphilic -COOLi in the vicinity of polymers, which maintains the uniform lithium flux and suppresses the deposition to achieve the smooth lithium growth. The lithiophilic -COOR group homogenized the Li+ flow at the electrode/electrolyte interface and alleviated the local lithium-ion flow. The LFP//Li cells assembled with the gel-electrolyte can still maintain a coulombic efficiency of 99% and capacity retention of 96% after 320 cycles at 1 C. And the NCM811//Li cells assembled with the gel-electrolyte can maintain about 90% coulombic efficiency and 88% capacity retention after 120 cycles at 0.5 C. In summary, this work provides an effective strategy for the application of next-generation high-safety lithium metal batteries. [ABSTRACT FROM AUTHOR]

In this study, a DOPO-based reactive flame retardant (DRFR) was synthesized and used as the second diphenol structure for preparation of flame-retardant rigid polyurethane foam (FR-RPUF). DRFR, as a phosphorus/nitrogen-containing diphenol, was prepared from 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), 4-hydroxy benzaldehyde, and benzidine. FR-RPUF was synthesized from polyether polyol (DaltoFoam TA® 14066) as the first hydroxyl-rich structure, DRFR as the second diphenol, and 4,4′-diphenylmethane diisocyanate through the one-pot method. For comparison, a pure rigid polyurethane foam (pure RPUF) was also synthesized without DRFR. The thermal stability of pure RPUF and FR-RPUFs was investigated by using thermogravimetric analysis (TGA). According to thermogravimetric analysis results, the temperature at 5 mass% loss (T5%) increased from 222 to 238 °C for sample containing 2 mass% of DRFR. Also, the char residue at 700 °C was enhanced by introducing DRFR. Flame retardancy and burning behavior were determined by the limiting oxygen index (LOI) and vertical burning test (UL-94). The LOI value of FR-RPUF sample containing 3 mass% DRFR achieved 21.5%, and the UL-94 test improved from no rating for pure RPUF to V-1 rating for FR-RPUFs. Compared with the pure RPUF, the resultant FR-RPUFs indicated better fire resistance and thermal stability. The dynamical mechanical thermal analysis results revealed that the storage modulus for FR-RPUFs is higher than pure RPUF, which attributed to the good interaction between DRFR and PU matrix. [ABSTRACT FROM AUTHOR]

Hexabromocyclododecane (HBCD) is a widely used brominated flame retardant; however, it is a persistent organic pollutant as well as affects the human thyroid hormones and causes cancer. However, the degradation of HBCD has received little attention from researchers. Due to its bioaccumulative and hazardous properties, an appropriate strategy for its remediation is required. In this study, we investigated the biodegradation of HBCD using Shewanella oneidensis MR-1 under optimized conditions. The Box-Behnken design (BBD) was implemented for the optimization of the physical degradation parameters of HBCD. S. oneidensis MR-1 showed the best degradation performance at a temperature of 30 °C, pH 7, and agitation speed of 115 rpm, with an HBCD concentration of 1125 μg/L in mineral salt medium (MSM). The strain tolerated up to 2000 μg/L HBCD. Gas chromatography-mass spectrometry analysis identified three intermediates, including 2-bromo dodecane, 2,7,10-trimethyldodecane, and 4-methyl-1-decene. The results provide an insightful understanding of the biodegradation of HBCD by S. oneidensis MR-1 under optimized conditions and could pave the way for further eco-friendly applications. Key points: • HBCD biodegradation by Shewanella oneidensis • Optimization of HBCD biodegradation by the Box-Behnken analysis • Identification of useful metabolites from HBCD degradation [ABSTRACT FROM AUTHOR]

Combining bio-based functional reagents and biopolymers has become a solution to address the needs of sustainability, health, and safety as society has grown. This study developed a waterproof and intumescent flame retardant system for epoxy resin (EP) by combining hexachlorocyclotriphosphazene and melamine with vanillin, synthesizing a ternary polymer flame retardant (HCPVM), combining carbon and gas sources, and using piperazine pyrophosphate (PAPP) as an acid source. The test results showed that HCPVM could participate in the curing reaction of EP and improve the mechanical properties of EP material. At the same time, the flame retardancy and water resistance of the material have been significantly improved. The peak heat release rate (PHRR) of EP/3.5 PAPP/0.5 HCPVM was 65.43% lower than that of pure EP. Additionally, the system's LOI and UL-94 did not significantly change after five days of boiling. In summary, this study's waterproof bio-based intumescent flame retardant solution broadens the application possibilities for EP. [ABSTRACT FROM AUTHOR]

Rational design morphology of flame retardant is crucial to achieving a balance between satisfactory flame retardancy and superior mechanical properties. However, there are few studies focused on the morphology of flame retardants, and how to achieve the aim of satisfactory flame retardancy yet low mechanical properties loss is still a challenge. Herein, aluminum diethylphosphinate (ADP) with different morphologies were obtained through hydrothermal synthesis method via adjusting the releasing rate of Al3+, molar ratio (OH−: Al3+), and changing the type of acid. The morphology of ADP was successfully regulated from random (ADP-1), rod-like (ADP-2) to flower-like (ADP-3). The formation mechanism of different morphology was discussed in detail. The TG results indicated that all ADP have high thermal stability. Therefore, ADP as flame retardant was used for modification of TPU. Compared to neat TPU, TPU/ADP composites present lower initial decomposition temperature and higher char residual. With addition of 30% ADP-2 the LOI value increased from 22.5 to 28.0%, achieved the UL-94 V-2 rating, respectively. THR was 25.6% lower than that of virgin TPU, exhibiting higher fire safety performance. Meanwhile the tensile strength of TPU composite with ADP-2 (10.8 ± 0.4) is higher than that of the composites with ADP-1 (8.7 ± 0.9), and ADP-3 (7.9 ± 0.5) at content up to 30%. This work provides a promising strategy to tune the morphology of flame retardant and compromise the contradiction of poor mechanical properties with high fire safety of polymer composite. [ABSTRACT FROM AUTHOR]

LDHs, 2D (two-dimensional) clay material with memory effect clutches noteworthy properties like high surface area, ion-exchange capacity, tunable properties and possibility for wide elemental as well as anion combinations. A variety of LDHs are being explored for profuse applications including catalysis, absorbent material, flame retardants, drug delivery, polymer additives and bone regeneration. Recent research updates reveal the promising potential of LDHs in bone tissue engineering and are expected to grab a major hold in futuristic medicare. There have been tremendous efforts concentrated on fine-tuning the LDHs properties by controlling the growth parameters to improve its multi-functionality. In this study, an effort has been made to synthesize and characterize Zn–Al LDHs via the co-precipitation method with control over the nucleation and hydrothermal growth steps. The interactions of the fabricated Zn–Al LDHs with human osteoblast (HOS) cells were explored in the context of bone regeneration applications. The effect of Zn–Al LDHs on the mitochondrial function of HOS cells was examined. The study also evaluated the potential of LDHs to trigger apoptosis by using DNA fragmentation as the marker. The potential impact of positively charged LDHs on negatively charged DNA was also probed using the DNA laddering assay, as an audit on genotoxic potential. [ABSTRACT FROM AUTHOR]

To reduce the fire risk of epoxy (EP) resin, a renewable lignin-based flame retardant functionalized with a metal–organic framework (MOF) HKUST-1 (Cu3(BTC)2, BTC = benzene-1,3,5-tricarboxylate) was prepared by a facile and green method. The chemical structure of flame retardant was characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that HKUST-1 was in-situ grown on the surface of phosphorus/nitrogen modified lignin, which was treated as an efficient flame retardant (termed PN-lignin@HKUST-1) for subsequent EP resin. The flame-retardant properties of EP composites were evaluated by the limiting oxygen index (LOI), vertical burning (UL-94), and cone calorimetry tests. As compared with neat EP thermoset, the presence of 15 mass% PN-lignin@HKUST-1 increased the LOI value from 28.5 to 33.2% and upgraded the UL-94 rating from V-2 to V-0. Besides, the peak heat release rate (PHRR) and total heat release (THR) were reduced by 41.2 and 33.8%, respectively. Observations of char residues could indicate that addition of PN-lignin@HKUST-1 contributes to a compact and dense char layer, which blocks the release and transfer of heat and harmful gases during combustion. [ABSTRACT FROM AUTHOR]

In this paper, a single-component intumescent flame retardant di-(3-aminopropyltriethoxysilane) spirocyclic pentaerythritol diphosphate (PDAP) was synthesized, imparting flame retardancy to polylactic acid (PLA), which using melt blending process. The chemical structure and thermal stability of PDAP were characterized by test methods such as Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA). The fire retardancy of PLA/PDAP was evaluated by test methods such as limiting oxygen index (LOI) and vertical burning test (UL-94). The thermal stability of PLA/PDAP was studied by TGA and thermogravimetry-Fourier transform infrared spectrometry (TG-FTIR). According to the results of laser Raman spectroscopy (LRS) and FTIR, the possible flame retardant mechanism of PLA/PDAP was discussed. With only 20 wt% addition of PDAP, PLA/PDAP could achieve 11.98% char residues at 800 °C. The LOI value of PLA/PDAP achieved 37%, UL-94 test reached V-0 rating. And higher fireproof performance with 62.1% reduced peak heat release rate (PHRR), 36.8% reduced total heat release rate (THR) and 19.5% reduced average effective combustion heat (av-EHC) value than PLA. The results show that PDAP has remarkable flame retardant effect on PLA, which provides an excellent research case for flame retardant modification of PLA plastic products. [ABSTRACT FROM AUTHOR]

This research studies the effect of aluminum hydroxide (ATH) on the thermal stability and flame retardant properties of nitrile rubber (NBR) composites containing IFR (Intumescent flame retardant). Differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and gas chromatography-mass spectrometry (GC/MS) were used to determine that adding 2 wt % flame retardant synergist ATH to NBR/IFR composites enhances the thermal stability of the composite and improves the charring effect of the IFR-containing composite. The flame retardancy of the composite is enhanced when 2 wt % ATH flame retardant synergist is added. The study suggests that the improved thermal stability and flame retardancy of the composite containing ATH may be due to the reaction of ATH with ammonium polyphosphate, which generates phosphate and increases the particle size of ATH. Additionally, this reaction produces high-temperature resistant inorganic compounds such as Al(H2PO4)3, which can easily connect ATH particles together to form aggregates, resulting in a layered char structure after combustion. [ABSTRACT FROM AUTHOR]

The paper presents a fully three-dimensional coupled simulation of flame propagation through epoxy resins reinforced with glass fiber (glass–epoxy) under the action of a heat flux from two sides, using the Fire Dynamic Simulator package. The model includes three-dimensional heat and mass transfer, diffusion of basic substances in the gas phase, and diffusion transport of pyrolysis products in the solid phase. The pyrolysis and oxidation processes are represented by macroreactions and take into account the effect of the phosphorus-containing flame retardant DDM-DOPO. The model satisfactorily predicts the experimentally observed dynamics of flame propagation. [ABSTRACT FROM AUTHOR]

The integration of high mechanical toughness, impact strength as well as excellent flame-retardant properties toward epoxy resins (EPs) have always been a dilemma. The inadequate overall performance of EPs severely restricts their sustainable utilization in engineering aspects over long-term. Herein, a new bio-based agent (diglycidyl ether of magnolol phosphine oxide, referred as DGEMP) derived from magnolol (classified as lignan), extracted from natural plants Magnolia officinalis, was successfully synthesized and further employed as a flame-retardant reactive additive to diglycidyl ether of bisphenol A (DGEBA). As demonstration, the composite resin, DGEBA/15DGEMP (15 wt% DGEMP), achieved an Underwriters Laboratories-94 V-0 rating with a high limiting oxygen index (LOI) value (41.5%). In cone calorimeter tests, it showed that heat release and smoke production were effectively inhibited during combustion, wherein the peak heat release rate (PHRR) value of DGEBA/15DGEMP was reduced by 50% compared to neat DGEBA. Additionally, it exhibited a superior tensile strength (82.8 MPa), toughness (5.11 MJ/m3) and impact strength (36.5 kJ/m2), much higher than that of neat DGEBA (49.7 MPa, 2.05 MJ/m3 and 20.9 kJ/m2). Thus, it is highly anticipated that DGEMP imparts significantly improved mechanical and fire-retarded properties to conventional EPs, which holds a great potential to address the pressing challenges in EP thermosets industry. [ABSTRACT FROM AUTHOR]

In living spaces where wood is commonly used for both construction and decoration, it is crucial to minimize electromagnetic pollution and the risk of fire. In this study, we applied aniline treatment to wood in situ and examined its impact on electromagnetic shielding and fire resistance. By enabling in situ polymerization and the deposition of polyaniline particles within the wood, we enhanced the wood's conductivity while maintaining its porous structure, thereby improving its ability to absorb microwaves. The results indicated that wood species with low density exhibited higher electromagnetic shielding efficiency after treatment due to their greater polyaniline loading. Specifically, an specific electromagnetic shielding efficiency up to 65.8 dB cm−3 g−1 was achieved on the cross sections of treated wood. Furthermore, the total heat release and smoke production decreased by 43.9% and 66.7%, respectively, while the wood char mass increased by 66.3%. The results demonstrated that polyaniline-treated wood with bifunctional features could serve as a promising candidate in this field. [ABSTRACT FROM AUTHOR]

Polyurethane foams (PUFs) are widely used in several applications including fire-alarm sensors, electromagnetic interference shielding, insulation material, and anti-corrosion coating. On the other hand, PUFs are highly flammable and their further development is dependent on their fire retardancy property. Therefore, development of PUFs with fire-retardant properties has been at the core of attention in recent years. Graphene-based nanomaterials (GNs) such as graphene and graphene oxide improve the thermal stability of PUFs and delay their ignition. In addition, GNS can suppress fire from spreading during PUFs burning. Despite the outstanding properties of GNs, their sheets may stack, shrink, and lose their large surface area. This directly affects their dispersion and compatibility with the parent polymer. To address these challenges, GNs can be modified with namely intumescent including an acid source, a gas source, and a carbon source and non-intumescent with zero, one, and 2D assembly materials. Incorporating modified GNs FRs into PUFs is performed using both surface coating, reactive, or additive methods. In the present review, the state-of-the-art reports on the use of modified GNs into PUFs have been highlighted. Moreover, the challenges of GNs flame-retardant PUFs as well as various strategies to tackle these challenges and improve the flame retardancy of PUFs are stated. [ABSTRACT FROM AUTHOR]

To enhance the flame retardancy and mechanical performance of epoxy resin, a P/N-containing oligomer, polyphosphate amide (PPA) was synthesized by 1,4-phenylenediamine with dimethyl methyl phosphonate without using any organic solvent. With only 2% PPA addition in EP, the sample passed the UL-94 V-0 grade, and its limited oxygen index reached 34.0%. In the cone calorimeter test, the peak heat release rate, total heat release, and total smoke release of the EP containing 2% PPA were reduced by 23.6%, 16.0%, and 22.7% compared with that of control EP, respectively. The toughness of the pure EP was 5.0 MJ m−3, and its impact strength and shear strength were 4.1 kJ m−2 and 8.4 MPa, respectively. With 2% PPA, the toughness, impact strength, and shear strength of EP/PPA2 were increased to 10.3 MJ m−3, 8.8 kJ m−2, and 14.8 MPa, respectively. This work provided a green and feasible strategy to fabricate a flame-retardant oligomer that was capable of enhancing the mechanical performance and fire resistance of the EP simultaneously. [ABSTRACT FROM AUTHOR]

The current global warming challenges have drawn refrigerants with low Global Warming Potential (GWP). R32 (difluoromethane) is the most promising low-GWP refrigerant and is slightly flammable. The addition of a flame retardant to HFC-32 can improve its flammability. Trifluoroiodomethane (R13I1) is a flame retardant with an extremely low GWP that can be employed as a refrigerant component. This experimental study investigates the effect of dispersing aluminium oxide (Al2O3) nanoparticles in the compressor oil with varying concentrations of 0.045, 0.09, 0.135, and 0.18 vol% in the Polyol Ester (POE) oil on its thermal, tribological, and rheological properties as well as on the overall performance of a vapour compression air conditioning system using ultra-low GWP mixture refrigerants consisting of R32, R161, and R13I1 as the working fluid. The thermophysical properties of the mixture refrigerant have been calculated using REFPROP (NIST properties of fluid reference). The mixture refrigerant (R32/R161/R13I1) performed better in alumina nanolubricant and the comparison has been made with reference to the base lubricant (POE) in terms of power consumption, COP, coefficient of friction, and cooling capacity. The results showed that the coefficient of performance (COP) and cooling capacity increased by 32.6% and 11.7%, respectively. The maximum power saving is up to 16.1%, and the coefficient of friction is reduced by 32.4%. The highest recorded thermal conductivity reached 22.5% at 343.15 K and a volume concentration of 0.18%, compared to base oil at 303.15 K. The air conditioning system's performance showed improvement at an optimal concentration of 0.135 vol%. This study provides valuable insights into identifying energy-efficient and low-GWP refrigerant alternatives suitable for air conditioning systems. [ABSTRACT FROM AUTHOR]

This paper conducted an experiment to study the burn-through behavior of vertical wood boards of different thicknesses with one surface heated by fire. The board thicknesses were 1, 1.5, and 2 cm, and the burner powers were 5, 10, and 15 kW to simulate the early stage of fire. The results show that burn-through is caused by the continuous charring and cracking of the board. After burn-through, the temperature and HRR begin to rise rapidly at about 100 s. According to the typical burning phenomena and HRR, the whole process presents three stages, including no charring on the back surface stage, burn-through stage and continuous flame spread stage. For boards made of logs, the burn-through time and positions are random due to non-uniform density distribution and different grains, and the uncertainty of the parameters can reach 27%. The charring process of the board is analyzed by the expansion of the charred area on the back surface and the advancement of the char front along the thickness direction. A quantitative method for the advancement of the char front along the thickness direction has been established, and the error between the calculated and experimental values is within 11.3%. [ABSTRACT FROM AUTHOR]

In the current study, aluminum phytate (AlPt) is used with huntite–hydromagnesite (HH) in plasticized poly(lactic acid) (PLA) in order to improve the fire-retardant performance of the composite. The flame retardant, thermal, and mechanical properties of the composites are investigated using the limiting oxygen index (LOI), horizontal and vertical burning test (UL-94), mass loss calorimeter, thermogravimetric analysis, tensile, and impact tests. According to the test results, the fire-retardant performance of the composite was improved when HH and AlPt were used together. The highest LOI value (33.8) and UL-94 rating of V0 were achieved with the addition of 5 mass% AlPt in the presence of 55 mass% HH. Further, the addition of AlPt did not change the flammability properties. AlPt showed its adjuvant effect predominantly in the condensed phase via improved char formation with enhanced barrier properties. Tensile and impact strength reduced as the added amount of AlPt increased due to the hydrolytic degradation of PLA during the extrusion process. [ABSTRACT FROM AUTHOR]

Polymers are widely employed in many areas, e.g. transport, packaging, electronic devices, etcetera. Among them, acrylonitrile–butadiene–styrene (ABS) is one of the most employed polymers due to its mechanical properties, its ease to mechanize and recyclability. Nevertheless, according to the fire properties, ABS behaviour is usually worse than other polymers, therefore, they have to be upgraded with flame retardant additives. To characterize the fire behaviour of a certain material is necessary to address several typology of tests, providing relevant properties such as thermal conductivity, flammability and heat released. However, researchers may not always be able to run all tests due to the lack of apparatus or samples. Therefore, it is necessary to seek bibliographic sources. As one might expect, for a given material, the property values should be similar, regardless of who performs the test. However, sometimes slightly different results are obtained, which may be due to different causes, such as differences in test set-up and in material composition/manufacture. These differences in properties may lead researcher to doubt which data to use. This paper presents the results of different types of tests using neat ABS polymer. Additionally, these results are compared with the data from literature, discussing the similarities/differences and offering a more comprehensive characterization of ABS. The laboratory techniques included in this work are: thermogravimetric analysis, differential scanning calorimetry, laser flash analysis, smoke density, cone calorimeter, fire propagation and flammability. [ABSTRACT FROM AUTHOR]

To enhance its properties, ammonium polyphosphate (APP) was subjected to modification using a synthesized phosphorus-containing silica gel, resulting in MAPP. Ammonium polyphosphate (APP) was modified by synthesized phosphorus-containing silica gel, resulting in MAPP, which was then used to form thermoplastic polyurethane composites. MAPP exhibited better thermal stability with a smaller dispersion size, lower initial decomposition temperature and better resistance to heat at high temperatures than APP. At the same time, MAPP showed more obvious advantages in improving the char yield, flame retardant performance and mechanical properties of TPU. TPU/5%MAPP showed a limiting oxygen index of 29.1% during burning tests, significantly better than TPU/5%APP (27.3%). The cone calorimeter test results also indicated that the incorporation of MAPP resulted in a significant reduction in key parameters such as peak heat release rate, total heat release, and total smoke release and an increase of the char yield of TPU composite. The TG result showed that the Tmax of the TPU/5%MAPP composite increased and the mass loss rate decreased compared with that of TPU/5%APP. Moreover, the tensile strength of the TPU/5%MAPP composite increased by 18.5% compared with the TPU/5%APP composite due to the improved dispersibility of MAPP than APP. An analysis of the fire resistance mechanism showed that the improved flame retardance in the TPU/5%MAPP composite resulted from the structural changes in the char residue. This study provides an efficient and extensible approach for the synthesis of high-performance flame retardant TPU materials. [ABSTRACT FROM AUTHOR]