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This review examines the fire retardant potential of natural fiber-reinforced polymer composites derived from plant fibers such as sisal, jute, hemp and coir etc. While these materials offer eco-friendly and cost-effective advantages, their inherent flammability remains a concern. The study consolidates various methodologies employed in evaluating the fire performance of these composites, encompassing cone calorimetry, Limiting Oxygen Index (LOI) test, UL-94 vertical burning test, Thermal Gravimetric Analysis (TGA), and smoke density test, which have been extensively discussed in prior literature. However, despite this coverage, there exists a gap in the lack of standardized evaluation methods and comprehensive studies addressing real-world conditions. To address these gaps, this review critically analyzes the existing research landscape and proposes strategies for improvement. It emphasizes the necessity for standardized testing protocols and comparative studies using uniform methodologies to enable direct comparisons among studies. Furthermore, the review suggests investigating the effects of environmental factors (humidity, temperature, UV exposure, and aging) on fire resistance and emphasizes longitudinal studies to assess the stability and durability of fire retardant treatments over extended periods. Additionally, it explores emerging eco-friendly fire retardant materials and nanotechnologies, highlighting their potential to enhance flame retardancy in natural fiber-reinforced polymer composites, while calling for further evaluation of their efficacy, compatibility, and environmental impact in future research endeavors. Through this, the review aims to bridge the gap between existing knowledge and practical application in improving the fire retardant properties of these composites for sustainable and safer material development. Fire retardant potential of natural fiber-reinforced polymer composites reviewed. Plant fibers like sisal, jute, hemp and coir used as reinforcement in polymer composites. Flammability concerns limit use in critical fire safety applications. Enhancement methods: fire retardant chemicals, coatings, and inorganic fillers. Challenges and future directions in improving fire retardancy discussed. Importance of developing eco-friendly and safe materials for various industries. [ABSTRACT FROM AUTHOR]

Highlights This research focuses on comparing the properties of molybdenum disulfide (MoS2) diffused coir fiber polyester composites (MCF‐PCs) with neat coir fiber polyester composites (NCF‐PCs) and exploring its applications in various industrial sectors such as automotive, construction and manufacturing, where mechanical strength and fire resistance are critical factors. The study aims to investigate the physical, mechanical, thermal degradation, fire performance, and vibration properties of these composites. Compression molding was used to develop composites with different coir fiber loadings (10%, 20%, and 30% by weight). MoS2 nanoparticles diffused on the fiber surface significantly improved mechanical characteristics, thermal stability, and fiber‐matrix compatibility. The findings indicate better crystallinity and physical properties in MCF‐PCs compared to NCF‐PCs. Morphological observations confirmed improved fiber‐matrix compatibility in MoS2‐diffused fiber composites with polyester. The MCF‐PC with 20% loading exhibited the highest tensile (28 ± 1.24 MPa), flexural (50 ± 0.50 MPa), and impact (15 ± 1.01 kJ/m2) strength. The flame retardancy of the composites was evaluated using a horizontal combustion test apparatus. In addition, MCF‐PCs exhibited better flame retardancy as evidenced by lower flame propagation velocity (9 ± 0.20 mm/min) and increased ignition time (13 ± 0.29 Sec). The MCF‐PC with 20% loading shows maximum natural frequencies of 77 ± 4.1 Hz. This study investigated MoS2‐diffused coir fiber‐reinforced polyester composites. Fiber‐matrix adhesion can be improved with modified fiber‐reinforced composites. The MoS2 diffusion on fibers improved the physical and mechanical properties of polyester composites. The MoS2 diffusion on fibers enhanced the thermal and vibrational characteristics of polyester composites. MoS2‐diffused natural fiber composites offer considerable research potential. [ABSTRACT FROM AUTHOR]

Natural fiber composites are not suitable for use in industries due to their flammability and low thermal resistance. Inorganic metal‐based fillers are known to enhance the flammability and thermal resistance of composites, while the thermal and fire‐retardant properties of organic fillers are not commonly known. This study evaluated the mechanical, thermal, and flammability properties of Ceiba petandra fiber (CPF)‐reinforced composites, which were added with snail powder (SP). To study the thermal resistance of the composite, a dynamic mechanical analyzer (DMA) and thermogravimetric analysis (TGA) were applied. SP Filler concentration increased the composite's tensile strength and thermal resistance. DMA test results showed the same trend as the composite's density value. The flame rate parameters of the composite, including the percentage of char yield and the limitation index oxygen (LOI), rose as the SP filler increased. However, the flame rate of the composite dropped because SP filler inhibited the movement of oxygen, combustible gas, and polyester degradation products. The addition of organic fillers in natural fiber composites promises better flammability and thermal resistance. [ABSTRACT FROM AUTHOR]

Hydrogen's wide flammability range causes its high-pressure jet flames to exhibit large-scale, high-temperature characteristics, posing risks of casualties and property damage. This study investigates the impact of different nozzle shapes and release pressures on flame behavior and temperature distribution through high-pressure hydrogen jet flame experiments. Circular outlets (0.5–4 mm diameter) and rectangular outlets (aspect ratios 1 to 8) are used, covering release pressures from 20 to 220 bar. High-pressure hydrogen is released through a nozzle into ambient air, igniting to form a flame. Flame length, width, and axial temperature are measured. Findings indicate that visible flame size increases with release pressure. The models for dimensionless visible flame length and width, considering the dimensionless heat release rate, are proposed for different nozzle shapes. Additionally, the dimensionless temperature rise along the flame axis is observed to be a function of the dimensionless distance and dimensionless heat release rate. • The hydrogen jet flame length and width varied regularly with the outlet shape. • The model of the flame length and width at rectangular outlets was proposed. • The flame temperature varied regularly with the outlet pressure, area and shape. • The model of the flame temperature distribution at circular outlets was proposed. • The model of the flame temperature distribution at rectangular outlets was proposed. [ABSTRACT FROM AUTHOR]

Contemporary applications require protection against overheating and electromagnetic radiation interference, preferably with reduced mass and enhanced basic performance, such as flammability or chemical or UV resistance and often also low or non‐electrically conductive. Materials exhibiting all these functions can be designed, but there is usually not just one but several different materials with advanced processing requirements; therefore, a simple manufacturing method providing percolation path formation involving powder mixing and hot pressing of providing excellent flexibility terpolymer comprising tetrafluoroethylene, hexafluoropropylene, and vinylidene fluoride monomeric units (THV)‐based nanocomposites is presented here. The addition of the graphene nanoplatelets (GNPs) and multiwalled carbon nanotubes (MWCNTs) significantly improves the EMI shielding effectiveness, up to SETOT = 23 dB for the GNP filler, SETOT = 17 dB for the MWCNT/GNP filler per 1 mm samples thickness and enhances almost 900% the thermal conductivity to almost 2 W/mK per GNP filler. Besides this improvement, the electrical conductivity remains at a low level, not surpassing 1.5 S/cm, which is, as mentioned above, beneficial in many applications, especially thermal management. Moreover, the proposed material is an excellent alternative to flexible foam or sponges. Highlights: Structural, electrical, EMI shielding, and thermal properties of flexible THV/GNP, THV/MWCNT, and THV/MWCNT/GNP nanocomposites are shown here.The oriented, long as over 1 mm filler paths are observed.The GNP filler provides the best thermal conductivity enhancement of over 800% compared to bare polymer.The EMI shielding effectiveness is dominated by absorption for all THV‐based nanocomposites.The electrical conductivity follows the power law, reaching σ = 1.49 S/cm for GNP‐filled nanocomposites. [ABSTRACT FROM AUTHOR]

The present work proposes to investigate the effect of an ultrahigh molecular weight silicone rubber (UHMW-SR) and two ethylene methyl acrylate copolymers (EMA) with different methyl acrylate (MA) content on the mechanical and fire performance of a fireproof acrylonitrile butadiene styrene copolymer (ABS) composite, with an optimum amount of ammonium polyphosphate (APP) and aluminum diethyl phosphinate (AlPi). ABS formulations with a global flame retardant weight content of 20 wt.% (ABS P) were melt-compounded, with and without EMA and UHMW-SR, in a Brabender mixer. During this batch process, ABS P formulations with UHMW-SR and/or EMA registered lower torque values than those of ABS P. By means of scanning electron microscopy (SEM), it was possible to observe that all ABS composites exhibited a homogenous structure without phase separation or particle agglomeration. Slightly improved interfacial interaction between the well-dispersed flame-retardant particles in the presence of EMA and/or UHMW-SR was also noticed. Furthermore, synergies in mechanical properties by adding both EMA and UHMW-SR into ABS P were ascertained. An enhancement of molecular mobility that contributed to the softening of ABS P was observed under dynamic mechanical thermal analysis (DMTA). An improvement of its flexibility, ductility and toughness were also registered under three-point-bending trials, and even more remarkable synergies were noticed in Charpy notched impact strength. Particularly, a 212% increase was achieved when 5 wt.% of EMA with 29 wt.% of MA and 2 wt.% of UHMW-SR in ABS P (ABS E29 S P) were added. Thermogravimetric analysis (TGA) showed that the presence of EMA copolymers in ABS P formulations did not interfere with its thermal decomposition, whereas UHMW-SR presence decreased its thermal stability at the beginning of the decomposition. Although the addition of EMA or UHMW-SR, as well as the combination of both in ABS P increased the pHRR in cone calorimetry, UL 94 V-0 classification was maintained for all flame-retarded ABS composites. In addition, through SEM analysis of cone calorimetry sample residue, a more cohesive surface char layer, with Si-O-C network formation confirmed by Fourier transform infrared (FTIR), was shown in ABS P formulations with UHMW-SR. [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]

This paper tackles the influence of the functionalization of polystyrene and graphene oxide (GO) composites on the flammability characteristics. A microscale combustion calorimeter (MCC) was used to experimentally determine the heat release capacity (HRC), the specific heat release rate (HRR) and the total heat released (THR). Neural models were designed that correlate the THR with a number of parameters related to the composition and type of flame retardant used, the heating rate, the amount of residue, the HRC, the peak heat release rate (PHRR), the temperature at the peak pyrolysis rate (TPHRR) and the time elapsed until the occurrence of the peak heat release rate (Time). The best results in the training, validation and testing stages were achieved with the neural model with 9 neurons in the input layer, 40 neurons in the hidden layer and one neuron in the output layer. This model was incorporated into an optimization procedure, based on a genetic algorithm, to establish the values of the input parameters used in the training of the neural networks, in order to generate a minimum THR value, which is the output parameter. Since the synthesis of polystyrene particles with different GO concentrations is costly, this research helps to reduce the number of experimental tests and allows to determine the best GO concentration by means of neural models and genetic algorithms. [ABSTRACT FROM AUTHOR]

Determining the structure and fuel load is key to know the flammability of vegetation in the Mediterranean Basin where forest fires are frequent. Determine which plant structural variable is best related to living and dead fuel to develop allometric equations in nine species in the Western Mediterranean Basin. In the east of the Iberian Peninsula (Valencia Province), we measured four structural variables (basal stem diameter, height, maximum diameter and perpendicular diameter) that were related, by means of allometric equations, to the living and dead fuel separated into different size classes. We also analyze fuel changes across developmental states of the studied species, and the vertical distribution of dead fuel. General equations that consider all development states can be used to determine living fuel. However to obtain dead fuel, we recommend using specific equations for each development state and fuel fraction for better accuracy. The basal stem diameter was the best structural variable in almost all cases for estimating fuel in the studied species. Dead fuel load throughout species' ontological development is a key factor to manage Mediterranean plant communities. [ABSTRACT FROM AUTHOR]

• The flammability limits of R13I1 + R152a/R600a/R1270 binary mixtures were measured. • The critical flammable volumetric ratios of R13I1 + R152a/R600a/R1270 were obtained. • A generalized equation for the LFL of R13I1 mixtures was provided. • F -number and HOC were calculated and the inhibitory effects of R13I1 were analyzed. Trifluoroiodomethane (R13I1) is a flame retardant with an extremely low global warming potential (GWP) and can be used as a component to improve the flammable characteristics of most promising low-GWP refrigerants. In this paper, the flammability limits of R13I1 + 1,1-Difluoroethane (R152a), R13I1 + isobutane (R600a) and R13I1 + propylene (R1270) binary mixtures were measured at 60 °C and atmospheric pressure with a 12 L flask according to ASHRAE standards. The critical suppression ratios of R13I1 + R152a, R13I1 + R600a and R13I1 + R1270 are 0.45, 2.24 and 0.99, respectively. A generalized equation for the lower flammability limit (LFL) of R13I1 mixtures was provided. With the LFL of the fuel gas in air and the ratio of R13I1 to the fuel gas, the developed generalized equation can calculated the LFL of R13I1 mixtures with a reasonable accuracy. The influence of R13I1 on the flammability of R152a, R600a and R1270 were studied. The LFL increases and heat of combustion (HOC) decreases significantly with the increase of the R13I1 concentration. The flammability inhibition effects of R13I1 decrease in the order: R152a > R1270 > R600a. [ABSTRACT FROM AUTHOR]

In this work, flame retarded thermoplastic polyurethane (TPU) composites were fabricated by introducing a novel flame retardant piperazine pyrophosphate. The flame retardany, thermal stability and combustion performance were systematically investigated. Flame retardant tests confirmed that thermoplastic polyurethane/piperazine pyrophosphate (TPU/PAPP) composites showed LOI of 27.5 vol% without any melt dripping when only 5 wt% PAPP was added. micro-combustion calorimetry (MCC) test implied that PAPP significantly suppressed heat release of TPU/PAPP composites. 10 wt% of PAPP endow PHRR1 and THR values TPU/PAPP10 decreased by 67.0% and 35.1% compared with TPU. Thermogravimetric-Fourier transform infrared spectroscopy (TG-FTIR) showed that PAPP significantly inhibited the release of toxic and combustible gases. The char residue investigation showed that TPU/PAPP composites formed compact char residue, which was able to effectively inhibit the heat and mass transmission in combustion. Based on the investigation, the work mechanism of PAPP in TPU/PAPP composites was proposed. [ABSTRACT FROM AUTHOR]

In this study, thiol-functionalized ladder-like polysesquioxanes end-capped with methyl and phenyl groups were synthesized via a simple sol-gel method and characterized through gel permeation chromatography (GPC), Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and thermogravimetric analysis (TGA). Additionally, epoxy blends of different formulations were prepared. Their structural, flame-retardant, thermal, and mechanical properties, as well as volatile organic compound (VOC) emissions, were determined using differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), TGA, scanning electron microscopy (SEM), limiting oxygen index (LOI), cone calorimetry, and a VOC analyzer. Compared to epoxy blends with flame retardants containing elemental phosphorus alone, those with flame retardants containing elemental phosphorus combined with silicon and sulfur exhibited superior thermal, flame-retardant, and mechanical properties with low VOC emissions. SEM of the residual char revealed a dense and continuous morphology without holes or cracks. In particular, LOI values for the combustion of methyl and phenyl end-capped polysilsesquioxane mixtures were 32.3 and 33.7, respectively, compared to 28.4% of the LOI value for the blends containing only phosphorus compounds. The silicon–sulfur–phosphorus-containing blends displayed reduced flammability concerning the blends using a flame retardant containing only phosphorus. This reflects the cooperative effects of various flame-retardant moieties. [ABSTRACT FROM AUTHOR]

Ozone, widely recognized as an environmentally friendly gas, is extensively used in various textile industry applications. These include pre-treatment processes like bleaching and desizing, as well as creating pattern and vintage effects, wastewater clarification, and surface modification. This study focuses on ozone as a novel solution to a specific challenge: addressing the reduction in flame retardancy properties experienced by flame-retardant (FR) polyester fabrics during post-treatment processes in the production line. Experimentation involved subjecting the fabrics to ozonation and exploring different combinations of ozone flow rates and treatment durations. Mechanical and functional properties of the fabrics were examined, with flammability tested according to International Maritime Organization (IMO) standards. Notably, treatment with a 5 L/min ozone flow rate, a 7.01 g/h ozone concentration ratio, and a duration of 10 min showed significant improvements in IMO values, ensuring compliance with required standards. Furthermore, treated samples underwent comprehensive tests for fastness and strength, yielding results within acceptable ranges. Fourier-transform infrared (FT-IR) and thermogravimetric analysis (TGA) measurements were conducted to evaluate the impact of ozonation. FT-IR results indicated that the presence of C-H groups associated with dyestuff contributed to decreased flame retardancy in the original fabric post-dyeing. However, these groups were effectively eliminated through ozonation, thereby enhancing the fabric's flame retardancy. [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]

Cellulose fabric testing for flame-retardant studies is frequently necessary in various textile applications. Natural cellulose material from ramie (Boehmeria nivea) is being promoted as an alternative raw material for the development of fire-resistant fabrics. This research aims to optimize the coating process of ramie fabric using a phosphorus-based flame retardant (FR) to enhance its flame-retardant characteristics. The FR treatment involves bleaching the fabric with H2O2; followed by fabric finishing using a formula comprising 3% (v/v) hydroxymethyl resin; phosphoric acid (2%); and two formulations of the flammable agent Flamatic DM-3072N: 40% (v/v) and 50% (v/v), applied using the pad-dry-cure method. The flame-retardant properties of the treated fabric are evaluated through flammability testing based on the ASTM D6413-08 standard, limiting oxygen index (LOI) analysis, and micrograph surface structure analysis with SEM. The results indicate that ramie fabric treated with the FR-50% material exhibits superior fire resistance, preventing fire spread on the fabric with a char length of 15–30 mm and a LOI value of 29. These findings highlight the potential of FR-treated ramie fabrics for various industries, including the automotive and protective clothing industries. [ABSTRACT FROM AUTHOR]

This study focuses on examining the influence of bast fibers on the flammability and thermal properties of the polylactide matrix (PLA). For this purpose, Urtica dioica and Vitis vinifera fibers were subjected to two types of modifications: mercerization in NaOH solution (M1 route) and encapsulation in an organic PLA solution (M2 route). In a further step, PLA composites containing 5, 10, and 15 wt% of unmodified and chemically treated fibers were obtained. The results of the tests show that only biocomposites containing mercerized fibers had a nearly 20% reduced flammability compared to that of PLA. Moreover, the biofiller obtained in this way belongs to the group of flame retardants that generate char residue during combustion, which was also confirmed by TGA tests. The M2 modification route allowed to achieve higher mass viscosity than the addition of unmodified and M1-modified fibers. The reason is that fibers additionally encapsulated in a polymer layer impede the mobility of the chain segments. The inferior homogenization of the M2-modified fibers in the PLA matrix translated into a longer combustion time and only a 15% reduction in flammability. [ABSTRACT FROM AUTHOR]

Rigid polyurethane foams (RPUF) filled with lignocellulosic fillers have gained considerable interest due to their mechanical performance and eco-friendly characteristics. However, their flammability and photodegradation resistance properties still need further improvement, which may be achieved by incorporating various particles. This study investigated the effect of adding 2.5% of wood flour and 5%–15% of an organophilic nanoclay (relative to the wood flour weight) on the RPUF morphology, density, compressive strength, thermal stability, flammability, and photodegradation resistance. The addition of wood flour and nanoclay made the RPUF cells more rounded and disrupted but did not affect density. The compressive properties were adversely impacted. Nevertheless, the nanoclay significantly improved both flammability and photodegradation resistance compared to the neat RPUF. [ABSTRACT FROM AUTHOR]

Inadequate fire resistance of polymers raises questions about their advanced applications. Flexible polyurethane (PU) foams have myriad applications but inherently suffer from very high flammability. Because of the dependency of the ultimate properties (mechanical and damping performance) of PU foams on their cellular structure, reinforcement of PU with additives brings about further concerns. Though they are highly flammable and known for their environmental consequences, rubber wastes are desired from a circularity standpoint, which can also improve the mechanical properties of PU foams. In this work, melamine cyanurate (MC), melamine polyphosphate (MPP), and ammonium polyphosphate (APP) are used as well-known flame retardants (FRs) to develop highly fire-retardant ground tire rubber (GTR) particles for flexible PU foams. Analysis of the burning behavior of the resulting PU/GTR composites revealed that the armed GTR particles endowed PU with reduced flammability expressed by over 30% increase in limiting oxygen index, 50% drop in peak heat release rate, as well as reduced smoke generation. The Flame Retardancy Index (FRI) was used to classify and label PU/GTR composites such that the amount of GTR was found to be more important than that of FR type. The wide range of FRI (0.94–7.56), taking Poor to Good performance labels, was indicative of the sensitivity of flame retardancy to the hybridization of FR with GTR components, a feature of practicality. The results are promising for fire protection requirements in buildings; however, the flammability reduction was achieved at the expense of mechanical and thermal insulation performance. [ABSTRACT FROM AUTHOR]

• Flammability limits of azeotropic mixtures consist of R1243zf are tested for the first time. • A brief mechanism for flame-retardant effect of R13I1, R227ea and R134a is analyzed. • CSCs of R1243zf mixtures are tested and compared with calculation results by 3 methods. 3,3,3-trifluoropropene (R1243zf) is a low climate change effect refrigerant that has great development potential. However, R1243zf is flammable and its safety classification is A2 as per ISO standard 817. To reduce its risk of flammability, the method of using mixed refrigerants in practical applications is an effective approach. In this paper, an experimental system was established according to the ASHRAE standard 34 to measure the flammability limits of four azeotropic mixtures containing R1243zf. First, the critical suppression ratio (CSR) of R13I1/R1243zf was tested out that is 0.353. Further measurements were made to determine the lower flammability limits (LFLs) and critical suppression concentrations (CSCs) of three ternary mixtures consisted of R1243zf, thermodynamic performance enhancer (RE170) and flame retardants (R13I1, R134a or R227ea), at various compositions. The experimental non-flammable proportions of R1243zf/RE170/R13I1, R1243zf/RE170/R134a, and R1243zf/RE170/R227ea were 31.81 %, 5.49 %, and 22.42 %, respectively. Besides, a comparison was made between the experimental data and the predicted results by means of three different theoretical methods (the equal effect method, thermal balance method, and group contribution method). The fresh experimental results will provide practical guidance for the applications that utilize the R1243zf blends in low flammability risk. [ABSTRACT FROM AUTHOR]

In order to improve the inherent flammability of polylactic acid (PLA) and make this new biodegradable material more widely used, B-modified ZSM-5 (B/Z5) was designed as synergistic agent of intumescent flame retardant (IFR), composed of ammonium polyphosphate (APP) and pentaerythritol (PER), and introduced into PLA/IFR (PLAs) to fabricate PLAs/B/Z5 composites by melt extrusion. The flame retardancy, surface morphology, and thermal stability of the composites were investigated by TG, LOI, UL-94, CCT, and SEM. The addition of B/Z5 makes the decomposition temperature of T5% as well as T10% of PLAs reduction in nitrogen atmosphere and carbon layer form in advance. UL-94 test shows the composites reach V-0 rating. LOI value also steadily increases, and the maximum value is 36.0% with B actual loading of 5.26% (recoded as 14B/Z5) in B/Z5. The PHRR decreases by 75% from 417.77 kW/m² for pure PLA to 103.19 kW/m2 for PLAs/14B/Z5, and THR reduces from 92.78 to 19.26 MJ/m2, which decreases by about 80% and the char yield reaches 50%. This study provides a simple and green method for the preparation of high flame-retardant PLA, which has a broad practical application prospect. [ABSTRACT FROM AUTHOR]

This article provides information about additives that are used to reduce the flammability of polymer compositions, in particular, flame retardants. At a certain degree of concentration of flame retardants in the material, the fire stops burning, due to various physical and chemical processes that occur, which do not allow the flame to ignite. The characteristics of the flame retardants used by the authors in their scientific research are given. These flame retardants are the following: aluminum hydroxide, magnesium hydroxide, melamine, zinc borate, ammonium polyphosphate. It has been studied that phosphorus-containing compounds have a plasticizing ability, and are also able to increase the fire resistance of plastics. Under the influence of high temperatures, metal hydroxides decompose. The formation of water dilutes the flammable gases that are released during decomposition, reducing the rate of combustion. The effectiveness of hydroxides depends on their content in the polymer. Magnesium hydroxide is more expensive than aluminum hydroxide, but has a higher heat resistance. Flame retardants are key components in reducing the destructive effects of fire. The addition of flame retardants to plastics increases the fire protection parameters of materials, as well as general safety and stability parameters. The use of flame retardants is important because modern homes, with an increasing number of electronic products, pose a higher risk of fire. Therefore, flame retardants provide protection against the destructive effects of fire of various materials. In turn, flame retardants are capable of providing a high degree of fire protection.

In boreal forests fires often ignite and spread within the dominant moss and lichen cover of the ground layer vegetation, which thus greatly influences fire hazard. We used an experimental set-up in greenhouse conditions to study the differences in how (1) fuel moisture and (2) wind velocity influence the ignition probability and fuel consumption among four common circumboreal ground vegetation fuels, Pleurozium schreberi (Willd. ex Brid.) Mitt., Hylocomium splendens Schimp., Dicranum spp. and Cladonia rangiferina (L.) F. H. Wigg. Our results show that the reindeer lichen C. rangiferina was clearly the most flammable species, with high ignition probability even at high moisture contents and low wind velocities. Of the mosses, Dicranum was the least flammable, with low ignition probability and mass loss at low wind velocities regardless of moisture content. P. schreberi and H. splendens behaved somewhat similarly with wind velocities quickly increasing the initially low ignition probability and mass loss observed in the absence of wind. However, especially for mass loss, among-species differences tended to disappear with stronger winds. The observed differences can be explained by the different structures and growth forms of the studied species and open a potential avenue for improving forest fire risk predictions.

The flammability of rigid polyurethane foam (RPUF) limits its application. A new type of chitosan phase-change microcapsule (CS/PCM) was successfully prepared by the condensation method with chitosan and gum acacia as the wall material and paraffin as the core material. CS/PCM was introduced into RPUF composite material as filler to improve the thermal and flame-retardant properties of polyurethane. The morphology, structure, thermal properties and flame retardancy of the materials were characterized by scanning electron microscopy (SEM), X-ray diffractometer (XRD), thermogravimetric (TG) analysis, differential scanning calorimetry (DSC) and cone calorimetry. It is found that when the CS/PCM content is 30 wt%, the latent heat of phase transition of RPUF-30 is 12.308 J/g, the limiting oxygen index (LOI) is 26.1% and the fire risk is reduced. The flame-retardant mechanism shows that the barrier effect provided by chitosan plays an important role in effectively blocking the transfer of heat and combustible gas, and improving the flame-retardant property of the composite. This paper provides a new idea for the application of CS/PCM in RPUF. [ABSTRACT FROM AUTHOR]

For many years, efforts have been made to reduce the flammability of unsaturated polyester resins (UPRs), which are often used in the rail, shipbuilding, and construction industries. Without modification, they often fail to meet fire safety standards. Despite a rich history of flame retardants (FRs) applied to UPRs, researchers seek new solutions that will provide lower flammability and smoke density, as well as attaining a lower environmental impact from the composites. The objective of the study is to highlight the most important recent research on promising nano FRs in order to promote their further development. Mechanisms of action of several groups of nano FRs, such as clay-based, carbon-based, transition metal compounds, layered double hydroxides, polyhedral oligomeric silsesquioxanes, and others, including bio-based, have been studied. Particular emphasis has been laid on nano FRs applied to UPRs, and their influences on thermal stability, flammability, and mechanical properties. Moreover, the environmental impact and toxicity of nano FRs have been discussed. Results have proved that nano FRs applied at low loadings may significantly improve thermal stability, with a simultaneous increase or only a slight decrease in mechanical properties. However, attention on related environmental issues has highlighted the necessity of carefully selecting novel nano FRs. [ABSTRACT FROM AUTHOR]

Limited by flammability, wood and wood-based materials face challenges in distinguishing themselves as structural materials or finishing materials. Once burning, they can produce toxic gases detrimental to humans and the environment. Therefore, it is critical to make clear whether fire-retardant wood construction materials are insusceptible to fire and not the sources of toxic gases. This study aimed to evaluate flame-retardant plywood from the aspects of flammability and the toxic gas and smoke generation during combustion. The flame-retardant plywood was manufactured by impregnating a flame-retardant resin in line with International Maritime Organization (IMO) standards. The research results indicate that seven out of the eight kinds of toxic gases listed by the IMO, other than CO, were not detected during the combustion of the flame-retardant plywood. While CO was detected, its quantities under three test conditions are below the corresponding thresholds. Therefore, unlike synthetic resin products, flame-retardant plywood is a promising finishing material that can reduce the damage from toxic gases in the event of a fire. In the smoke generation tests, the mass reduction rate of flame-retardant plywood increased from 13% to 18% and then to 20% as the test condition became more severe. Under the same circumstances, the average maximum specific optical density also followed an upward trend, whose values (75.70, 81.00, and 191.20), however, still met the IMO standard of below 200. This reflects that the flame-retardant plywood is competent as a finishing material. Further, flammability was evaluated, and the critical flux at extinguishment (CFE), total heat release (Qt), and peak heat release rate (Qp) were determined to be 49.5 kW/m2, 0.21 MJ, and 0.66 kW, respectively, which all did not reach the corresponding thresholds given by the IMO. To sum up, flame-retardant plywood has satisfactory flame-retardant performance and meets fire safety standards, showing the potential to be an attractive finishing material for building and construction. [ABSTRACT FROM AUTHOR]

Regarding environmental preservation, the upcycling of plastics from petroleum source is a consistent alternative. This work intended to investigate melting extruded composites of post-consumer HDPE (rHDPE) filled with pristine zirconium phosphate (ZrP), aluminum hydroxide [Al(OH)3] and aluminum hydroxide modifying-zirconium phosphate [ZrPOct/Al(OH)3]. Physico-mechanical and flame retardancy were assessed. FTIR revealed that rHDPE brought some degree of oxidative degradation probably from its cleaning process and/or processing. By nuclear magnetic resonance at time domain, rHDPE showed three relaxation domains. Fillers induced the lowering of rHDPE relaxation time owing to polymer/filler by hydrogen bonds. Diffraction pattern of rHDPE/Al(OH)3 and rHDPE/ZrPOct/Al(OH)3 indicated better fillers' dispersion. Fillers changed rHDPE crystallinity degree and thermal stability but rheologic properties were invariable. For all composites, elastic modulus increased (up to 17%) indicating stiffening. Yield strength did not change but stress and strain at break decreased. For the composites, SEM/EDS showed better dispersion and distribution of ZrP and ZrPOct/Al(OH)3 particles. It was assumed that ZrP and ZrPOct/Al(OH)3 greatly increased the flame retardancy. The work corroborates the importance of polymers' upcycling, and it is in consonance with the objectives of 2030 Agenda released by United Nations. [ABSTRACT FROM AUTHOR]

Reestablishing appropriate tree species is an important step in converting off‐site monocultures into woodlands. Species conversion is often necessary, as off‐site exotic species rarely function like woodland species. However, when off‐site tree species are native, and functionally redundant to woodland species, conversion may be unnecessary. To explore this possibility in the southeastern United States, we reviewed the literature on trait differences among the primary southern pines and qualitatively assessed the effect of their identity at the species and stand‐levels. In this region, woodland restoration focuses on removing loblolly (Pinus taeda) and slash pine (P. elliottii) to reestablish longleaf (P. palustris) or shortleaf pine (P. echinata). Our review found minimal variation among species in understory flammability, fire resistance at maturity, and Red‐cockaded Woodpecker (Leuconotopicus borealis) habitat at the stand‐level. Longleaf and shortleaf pine were generally more resistant to abiotic and pest disturbance at the tree‐level; however, stand‐level differences in wind, drought, and boring insect resistance among southern pines growing in open forests were considered minimal. Retaining loblolly and slash pine will improve stand‐level productivity in the short term, but creates regeneration problems due to low juvenile fire resistance and resilience. Ice resistance and long‐term carbon sequestration will also likely be reduced by retaining loblolly and slash pine. Collectively, these results suggest that southern pine species are generally interchangeable at the stand‐level in woodlands; although woodlands featuring loblolly and slash pine may be less stable in the face of disturbance than those dominated by shortleaf and longleaf pine. [ABSTRACT FROM AUTHOR]

In this research, a series of silicone foam/polytitanosiloxane composites (SF-pTS) were fabricated with hydroxy-, vinyl-, hydrogen-containing polydimethylsiloxanes, and polytitanosiloxane filler in the presence of a platinum catalyst under ambient conditions. The effect of the amount of polytitasiloxane on the micromorphology and flame retardancy of silicone foam was studied, and a relative flame retardancy mechanism was proposed. It could be found that the polytitanosiloxane exhibited a good dispersion level in the silicone foam, thus improving the flame retardancy of the composite. When the content of polytitanosiloxane is 9 wt%, the limiting oxygen index and UL-94 grade of the SF-pTS9 composite are increased to 29.2% and FV-0, respectively. Cone experiment results suggested that the SF-pTS9 possessed relative balanced PHRR (148.9 kW/m2), THR (58.5 MJ/m2), TSP (0.6 m2), and mass residue (83.9%) among the prepared silicone foam materials. This work provides a new avenue to fabricate a silicone foam composite with enhanced flame retardancy. [ABSTRACT FROM AUTHOR]

Purpose: It is an indispensable part of airworthiness certification to evaluate the fuel tank flammability exposure time for transport aircraft. There are many factors and complex coupling relationships affecting the fuel tank flammability exposure time. The current work not only lacks a comprehensive analysis of these factors but also lacks the significance of each factor, the interaction relationship and the prediction method of flammability exposure time. The lack of research in these aspects seriously restricts the smooth development of the airworthiness forensics work of domestic large aircraft. This paper aims to clarify the internal relationship between user input parameters and predict the flammability exposure time of fuel tanks for transport aircraft. Design/methodology/approach: Based on the requirements of airworthiness certification for large aircraft, an in-depth analysis of the Monte Carlo flammability evaluation source procedures specified in China Civil Aviation Regulation/FAR25 airworthiness regulations was made, the internal relationship between factors affecting the fuel tank flammability exposure time was clarified and the significant effects and interactions of input parameters in the Monte Carlo evaluation model were studied using the response surface method. And the BP artificial neural network training samples with high significance factors were used to establish the prediction model of flammability exposure time. Findings: The input parameters in the Monte Carlo program directly or indirectly affect the fuel tank flammability exposure time by means of the influence on the flammability limit or fuel temperature. Among the factors affecting flammability exposure time, the cruising Mach number, balance temperature difference and maximum range are the most significant, and they are all positively correlated with flammability exposure time. Although there are interactions among all factors, the degree of influence on flammability exposure time is not the same. The interaction between maximum range and equilibrium temperature difference is more significant than other factors. The prediction model of flammability exposure time based on multifactor interaction and BP neural network has good accuracy and can be applied to the prediction of fuel tank flammability exposure time. Originality/value: The flammability exposure time prediction model was established based on multifactor interaction and BP neural network. The limited test results were combined with intelligent algorithm to achieve rapid prediction, which saved the test cost and time. [ABSTRACT FROM AUTHOR]

In this work, we employed a two-step modification process to improve the properties of 2D bimetallic nanoplates M(OH)(OCH3) (M = Co, Ni), which were recently proven as a promising "nano-flame retardant". The nanoplates were in situ modified with metal-organic framework ZIF-67 first and then silanized with a coupling agent APTES. Epoxy resin (EP) nanocomposites were fabricated using the functionalized M(OH)(OCH3). We investigated the performance of the nanocomposites in flame retardance and thermal stability. The results showed that 3% of APTES@ZIF-67@M(OH)(OCH3) gave the EP nanocomposite the V-1 rating in UL-94 test and the highest limited oxygen index of 27.6%. Moreover, the pHRR value of EP/APTES@ZIF-67@M 3% was reduced by 20.0% and 9.6%, respectively, compared to neat EP and EP/ZIF-67@M 3%. Regarding the mechanical properties, the Tensile properties and energy storage modulus of EP nanocomposite were both improved with 3% of APTES@ZIF-67@M(OH)(OCH3). The GC-MS test results revealed that the functionalized M(OH)(OCH3) significantly increased the cross-linking propensity of the EP matrix upon combustion, leading to the formation of a dense char layer. This study demonstrates the great potential of M(OH)(OCH3) as a highly efficient "nano-flame retardant" with tunable functionality. [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]

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]

Water-blown biopolyurethane (bioPUR) foams are flammable and emit toxic gases during combustion. Herein, a novel approach suggested by the current study is to use different amounts of lignin waste (LigW), which increases the thermal stability and delays the flame spread and sodium silicate (LG), which has foaming ability at high temperatures and acts as a protective layer during a fire. However, there have been no studies carried out to investigate the synergy between these two materials. Therefore, two different ratios, namely 1/1 and 1/2 of LigW/LG, were used to prepare bioPUR foam composites. The obtained bioPUR foam composites with a 1/2 ratio of LigW/LG exhibited inhibition of flame propagation during the ignitability test by 7 s, increased thermal stability at higher temperatures by 40 °C, reduced total smoke production by 17%, reduced carbon monoxide release by 22%, and increased compressive strength by a maximum of 123% and 36% and tensile strength by a maximum of 49% and 30% at 100 °C and 200 °C, respectively, compared to bioPUR foam composites with unmodified LigW. Additionally, thanks to the sufficient compatibility between the polymeric matrix and LigW/LG particles, bioPUR foam composites were characterised by unchanged or even improved physical and mechanical properties, as well as increased glass transition temperature by 16% compared to bioPUR foam composites with unmodified LigW particles, making them suitable for application as a thermal insulating layer in building envelopes. [ABSTRACT FROM AUTHOR]

Incorporating nano-sized fillers into bio-based polyurethane (PU) foams typically enhances their properties. In present investigation, palm oil-based PU foams are fabricated with varied loadings (0 to 5 wt%) of fumed nanosilica. The foams are then characterized for their fire-retardancy, thermal stability, foam morphology, and also mechanical properties. Marginal improvement in Limiting Oxygen Index (LOI) values, as well as failure to be rated under UL-94 Vertical Combustion Test indicate limited potential of fumed silica in improving flammability of organic polymeric foams; suggesting exorbitant amount is required for any distinguishable effect to manifest. Interestingly; results from Thermogravimetry Analysis (TGA) shows marked improvements in terms of char residue with more than seven-fold increase at 5 wt% filler loading, possibly owed to the inert filler nature of fumed nanosilica forming a char barrier and acting as fuel diluent. Filled PU foams displayed an increased open-cell content, likely because the filler functioned as a cell opener. Removing the influence of density, the normalized compressive properties showed notable improvement up until a certain loading, which could be credited to the increased stiffness imparted by the filler itself. The results portray the potential of fumed nanosilica as filler for bio-based PU foams, offering enhanced thermal stability and limited fire retardancy. [ABSTRACT FROM AUTHOR]

The effect of expanded vermiculite (e-VMT) was evaluated relative to the physical, mechanical, and flame retardancy performance of flat-pressed wood plastic composites (WPCs). Various contents of e-VMT (2.5, 5, 7.5, 10, 15%) were added instead of wood flour (WF) to the matrix. Due to the hydrophilic nature of the WF, water absorption (WA) and thickness swelling (TS) of WPCs increased as compared to neat polymer-based panels. Meanwhile, e-VMT incorporation limited the WA and TS values. As expected, the lowest WA and TS values were obtained from the highest e-VMT-reinforced WPCs. The addition of e-VMT was also found to enhance the mechanical properties of WPCs. As the e-VMT content increased and the WF content decreased, there was an improvement in flexural strength, modulus of elasticity (MOE), and tensile strength. Compared to the neat polymer panels, the MOE of WPCs increased by up to 77%. Additionally, the flame retardancy performance of WPCs improved with e-VMT reinforcement, with limiting oxygen index (LOI) values increasing up to 24%. Scanning electron microscopy (SEM) images also demonstrated the favorable integration of e-VMT with matrix, thereby improving the mechanical properties. The inconsistency between WF and polymer was also well-observed, highlighting the tendency of WF to interact easily with water. [ABSTRACT FROM AUTHOR]

Flax fabric textile is of great interest as bio‐fiber reinforcement in composites, which has gained popularity due to the high demand for sustainable materials. Despite its sustainability, flax is inherently flammable. This study demonstrates a two‐step polyelectrolyte complex (PEC) coating that renders flax fabric self‐extinguishing. The PEC coating consists of polyethylenimine (PEI) and sodium hexametaphosphate (PSP), cured with a citric acid buffer. Sonication employed during the curing process improves the infiltration of the coating into the flax fibers and maintains the fabric's hand. When comparing non‐sonicated and sonicated flax samples, the latter achieves self‐extinguishing behavior and passes the vertical flame test. Pyrolysis‐combustion flow calorimetry reveals that this PEI/PSP coating (with sonication) reduces the peak heat release rate and total heat release by 40% and 67%, respectively. The intumescent mechanism is predominantly observed in the condensed phase, as suggested by differential scanning calorimetry and X‐ray photoelectron spectroscopy. The results demonstrate that the two‐step PEC treatment with sonication effectively reduces the flammability of flax fabric, making it a promising option for the development of functional fibers, particularly for bio‐composite reinforcement. [ABSTRACT FROM AUTHOR]

The presence of massive amounts of toxic volatiles and smoke during combustion is a very serious problem facing epoxy resin (EP) composites. Therefore, flame retardants (FRs) can simultaneously enhance flame retardancy and reduce the release of smoke and fatal gases. Herein, a novel sulfur–phosphorous reactive flame retardant (SPMS) was synthesized for epoxy resin. The high efficiency of smoke suppression and flame retardancy of the EP/SPMS-APP hybrid was investigated using a cone calorimeter, a vertical burning test, and limited oxygen index measurements. Compared with those of pure EP, the composite with 20 wt% SPMS-APP reduced the peak heat release rate (pHRR), the peak smoke production rate (SPR), and total smoke production rate (TSR) by 82%, 94%, and 84%, respectively. The results showed a remarkable suppressed effect of alleviating the fire hazard of EP using a sulfur–phosphorus flame retardant. [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]

Due to the increasing demand for low carbon fuels, ammonia is considered a viable option. Considering the problems associated with the combustion of ammonia, such as its narrow flammability range, it has been suggested to use it together with other fuels, such as methane. Following previous studies, which mainly focus on the emission of this fuel mixture in burners and simplified chambers, this research attempts to conduct an experimental and numerical study with a greater emphasis on performance parameters and pollution in an actual microturbine combustion chamber. The study investigates the effect of a mixture of ammonia with methane and its fraction on the combustion performance of the combustor and its emissions (NOx, CO) in two different thermal powers. The results showed that flame temperature decreased as the fraction of ammonia in the fuel increased, and the flame moves away from the injector. It also appeared that adding ammonia to the fuel increased the amount of NOx produced in the combustor without reducing CO significantly. Also, the combustor outlet temperature remained almost unchanged, but the combustion efficiency of the combustor decreased as the ammonia fraction increased. • Investigated performance and emissions of microturbine combustor with ammonia/methane fuel mixture. • Stable combustion achieved up to 50% mixing ratio, without altering combustor configuration. • Lowering reaction rate delays ignition and hampers chamber performance. • Ammonia in methane reaction reduces complete combustion, causing elevated CO and NOx emissions. • Higher ammonia ratio reduces combustor efficiency, raises pattern factor, with constant output temperature. [ABSTRACT FROM AUTHOR]

In this study, numerical methods were used to assess the effects of adding hydrogen and varying the equivalence ratios on the combustion and emission properties of a non-premixed combustor. The results revealed that the additions of H 2 and varying Φs significantly affected the flame configuration and emission characteristics. An elevation in the H 2 vol. Promotes fuel combustion, yielding a higher flame temperature and a wider flammability region. Lower Φs and increased H 2 vol. Significantly decrease CO and CO 2 emissions by 87.48% and 96.63% respectively. Conversely, NOx emissions increase with higher H 2 vol. and Φs due to the catalytic effect of elevated flame temperature. At Φ = 0.2 and 50 vol% of H 2 , outlet temperature and pattern factor were enhanced by 61.66% and 30.16% respectively. Under these conditions, NOx emission was calculated by a factor of 74.14. Investigation emphasizes hydrogen-enriched fuels' potential for enhancing combustion and emissions control through vol. and equivalence ratios. • Hydrogen-enriched fuel mixture combustion is realized in a can-type combustor. • Effects of H 2 enrichment and equivalence ratios on combustion are investigated. • The addition of H 2 in the fuel mixture enhances combustion performance. • CO, CO 2 , and NO x pollutant emissions are numerically computed. [ABSTRACT FROM AUTHOR]

[Objective]To study the burning characteristics of litters from different common forest types in west Sichuan can help assess the risk and intensity of surface fires in different forest types.[Method]Six common forest types in the western Sichuan region were selected and their litter moisture content, ash content, ignition point, dry weight calorific value（GCV）,and ash free calorific value（AFCV） were measured.By using principal component analysis, the variation in burning characteristics across different forests were comprehensively evaluated.[Result]The results showed that the differences in moisture content, ignition point, gross calorific value（GCV）,and ash-free calorific value（AFCV） were significant among different forest types.Through comprehensive analysis, the flammability of litters from six common forest types in western Sichuan was ranked as follows: Pinus radiata ＞ Pinus densata ＞ Pinus armandii ＞ Quercus semicarpifolia ＞ Pinus yunnanensis＞Picea asperata-Abies fabri. [Conclusion]In this study, we measured and analyzed the burning characteristics of litters from six common forest types in western Sichuan.Our study can help predict the risk and intensity of surface fires in different forest types, and provide references for fire prevention. [ABSTRACT FROM AUTHOR]

Transparency is an important property for polymer flame retardants, especially epoxy resin (EP) flame retardants, and flame-retardant epoxy resins that maintain a high transparency and low chromatic aberration play important roles in the optical, lighting, and energy industries. Herein, a DOPO-based flame retardant 6,6′-((sulfonylbis(4,1-phenylene))bis(oxy))bis(dibenzo[c,e][1,2]oxaphosphinine 6-oxide) with a high transparency and low chromatic aberration was prepared via the classical Atherton–Todd reaction and named SBPDOPO. Its chemical structure was characterized with Fourier IR spectroscopy and NMR spectroscopy. An EP loaded with 7 wt% SBPDOPO passed the UL-94 V-0 rating with an LOI value of 32.1%, and the peak heat release rate, total heat release, and total smoke production were reduced by 34.1%, 31.6%, and 27.7%, respectively, compared with those of pure EP. In addition, the addition of SBPDOPO improved the thermal stability, residual mass, and glass transition temperature of the EP. On this basis, the EP containing 7 wt% SBPDOPO maintained a high transparency and low color aberration, with a transmittance of 94% relative to that of pure EP and a color aberration ΔE of 1.63. Finally, the flame-retardant mechanism of SBPDOPO was analyzed, which demonstrated that it exerted both gas-phase and condensed-phase flame-retardant effects, and that SBPDOPO/EP had high potential for application scenarios in which both flame retardancy and transparency are needed. SBPDOPO/EP has great potential for applications requiring both flame retardancy and transparency. [ABSTRACT FROM AUTHOR]

This work aims to improve the thermal stability and flame retardancy of cotton fabrics treated just by a single SiO2, a single B2O3 and their binary composite sol–gel systems. Tetraethyl orthosilicate (TEOS) and tributyl borate were used as precursors. The sols were coated onto cotton fabrics via dipping-baking processes. Techniques including Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Scanning electron microscope (SEM), energy-dispersive X-ray spectroscopy (EDS), thermogravimetric analysis (TGA), limiting oxygen index (LOI) and vertical burning test (VBT) were used to investigate the surface functional groups, elemental compositions, crystal structures, surface morphologies, elemental contents, thermal stability and flame retardancy levels of original and sols-treated cotton fabrics, respectively. The results show that the sols converted gel coatings are successfully deposited on the cotton fabric surfaces. SiO2-B2O3 sol finishing cotton fabric shows the best flame retardancy. It shows the highest char residue rate (43.82%), the highest LOI (25.7%) and ΔLOI/Δm (7.0%/g), the lowest after-flame time (10.0 s) and after-glow time (0.0 s without a smoldering process), a relatively complete and continuous char residue after a VBT. The SiO2 and B2O3 sol–gel systems play more synergistic effects than competitive effects in flame retarding a cotton fabric. A SiO2 gel shows effects of a high melting point, a structural support and dimensional stability, while a B2O3 gel shows a fusing capability and a longer pyrolysis process. [ABSTRACT FROM AUTHOR]

• The flammability limits of R134a/R1270, R134a/R170 and R170/R1270 were measured. • R134a demonstrates a significant flame-retardant effect at volume ratios above 0.75. • The flame color and propagation speed of refrigerants were compared and analyzed. Hydrocarbons (HCs) are considered promising alternative refrigerants due to their excellent thermodynamics, transport properties, and environmental friendliness. However, hydrocarbons are flammable. Conversely, R134a is a widely used non-flammable refrigerant but was listed in the Montreal Protocol-Kigali Amendment due to its relatively high global warming potential (GWP). Therefore, in order to reduce the GWP of R134a and inhibit the flammability of hydrocarbon refrigerants, this study investigated the flammability characteristics of mixed refrigerants R134a/R1270, R134a/R170, and R170/R1270. The flammability limits of different concentrations of R170/R1270, R134a/R1270, and R134a/R170 were measured under standard conditions, and the inhibition mechanism of R134a was briefly analyzed. Additionally, the flammability limits of R170/R1270, R134a/R1270, and R134a/R170 were predicted using the polynomial fitting method. Subsequently, the flame propagation speed and the flame color of R1270 and R170, with and without R134a, were compared and analyzed. Furthermore, the cycle performance of R134a/HCs was calculated. The research results are expected to provide guidance for the safe and effective utilization of R1270, R170, and their mixtures in refrigeration systems. [ABSTRACT FROM AUTHOR]

To enhance the safety grade and broaden the application scope of polypropylene in coal mines, the calcium alginate@ammonium polyphosphate@graphite microsheet (CA@APP@GM) had been synthesized and introduced into the polypropylene (PP) material to endow excellent flame retardancy, antistatic characteristics, thermostability, combustion behavior, and mechanical performance. Physical characterizations on the chemical composition and microstructure of both the gaseous and condensed phase products indicated that the phosphorus‐containing compounds were found in the char residue which were beneficial to accelerate the charring reaction to terminate the mass and heat transfer process. Hence, the CA@APP@GM executed the condensed‐phase flame‐retardant mechanism to enhance the fire resistance of PP matrix. Consequently, it is believed that the CA@APP@GM, with its remarkable flame retardancy and antistatic properties, has the potential to significantly expand the range of applications for PP materials in coal mines. [ABSTRACT FROM AUTHOR]