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In this study, fly ash (FA) which mainly consists of SiO2, Al2O3, Fe2O3, MgO, and CaO, was used as a synergistic additive (1–5 wt %) to improve the effectiveness of an intumescent flame retardant (IFR) system (25 wt %) in high density polyethylene (HDPE). IFR system composed of ammonium polyphosphate and pentaerythritol (3/1 ratio), and different amounts of FA were incorporated homogeneously into HDPE. Thermogravimetric analyses and thermal conductivity measurements were performed to determine the thermal properties. Meanwhile, limiting oxygen index, UL 94 vertical burning, and cone calorimetry tests were performed to investigate the fire resistance. Furthermore, the effects of IFR/FA additions on the mechanical properties were determined. The experimental results showed that IFR and IFR/FA additions resulted in early degradation with lower rates, and the residual mass values increased due to the char layers and the FA content. Also, IFR addition increased the thermal conductivity coefficient from 0.451 W/mK to 0.462 W/mK and IFR/FA additions further increased the coefficient up to 0.506 W/mK. Although the sample included only 25 wt % IFR could meet the requirements of UL 94 V-2 with a LOI value of 25.0%, 2, 3 and 4 wt % FA additions satisfied the criteria of UL 94 V-0 with a LOI value of 26.6%. In addition, the cone calorimeter results revealed that the peak heat release rates and total heat released values decreased with IFR (25 wt %) and FA (2, 3, and 4 wt %) additions. Furthermore, CO, CO2, and soot emissions of the composites significantly reduced with respect to HDPE. The NO increased with IFR additions due to the nitrogen content of APP. 25% IFR addition caused decreases in the tensile strength, tensile modulus, and Izod impact strength. However, FA additions slightly enhanced the mechanical properties of HDPE/IFR composite. [ABSTRACT FROM AUTHOR]

The flammability properties of polymers and polymeric composites play an important role in ensuring the safety of humans and the environment; moreover, flame-retardant materials ensure a greater number of applications. In the present study, we report the obtaining of polypropylene (PP) composites contain a mixture of two green flame retardants, lignin and clinoptilolite, by melt extrusion. These additives are abundantly found in nature. Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), mechanical properties, scanning electron microscopy–energy dispersive X-ray spectroscopy (SEM-EDS), cone calorimetry, UL-94, and carbonized residues analysis were carried out. TGA analysis shows that PPGFR-10 and PPGFR-20 compounds presented better thermal stability with respect to PP without flame retardants. The conical calorimetric evaluation of the composites showed that PPGFR-10 and PPGFR-20 presented decreases in peak heat release rates (HRRs) of 9.75% and 11.88%, respectively. The flammability of the composites was evaluated with the UL-94 standard, and only the PPGFR-20 composite presented the V-0 and 5VB classification, which indicates good flame-retardant properties. Additives in the polymer matrix showed good dispersion with few agglomerates. The PPGFR-20 composite showed an FRI value of 1.15, higher percentage of carbonized residues, and UL-94 V-0 and 5VB rating, suggesting some kind of synergy between lignin and clinoptilolite, but only at high flame-retardant concentrations. [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]

The flammability of epoxy resins and knowing how to achieve curing are particularly important factors during use. A novel approach for enhancing the fire resistance and reducing the smoke emission of epoxy resin during the curing process is suggested, which involves the utilization of a three-source integrated polymerization intumescent flame-retardant. In this study, the synthesis of poly 4,4-diaminodiphenylsulfone spirocyclic pentaerythritol bisphosphonate (PCS) is achieved through using solution polymerization, utilizing 4,4′-diaminodiphenylsulfone (DDS) and spirocyclic pentaerythritol bisphosphorate disphosphoryl chloride (SPDPC) as initial components. Following that, the EP underwent the inclusion of PCS to examine its resistance to heat, its ability to prevent flames, its effectiveness in reducing smoke and its curing effect. Compared to the unmodified epoxy resin, the addition of PCS can not only cure the epoxy resin, but also decompose before the epoxy resin and has a good carbonization effect. With the addition of 7 wt.% PCS, the LOI value can achieve 31.2% and successfully pass the UL-94 test with a V-0 rating. Moreover, the cone calorimeter experiment demonstrated a noteworthy decline of 59.7% in the maximum heat release rate (pHRR), 63.7% in overall heat release (THR), and 42.3% in total smoke generation (TSP). Based on the examination of TG-FTIR and SEM findings, there is ample evidence to suggest that PCS, functioning as a phosphorus-nitrogen intumescent flame-retardant that combines three origins, has the potential to exhibit a favorable flame-retardant impact in both its gas and condensed phases. [ABSTRACT FROM AUTHOR]

[Display omitted] Despite the advantages of easy moulding and excellent mechanical properties, there are still some shortcomings with polypropylene (PP) such as high flammability and poor ultra-violet (UV) resistance. In this work, modified zinc oxide (mZnO) was prepared by reacting zinc oxide nanoparticles (ZnO) with polysiloxanes, and the effect of mZnO on the effectiveness of intumescent flame-retardant and on the UV aging resistance of polypropylene were investigated. By introducing 16 wt% (intumescent flame-retardant /mZnO) and 0.3 wt% maleic anhydride-grafted PP (MAH-g-PP), the limiting oxygen index increased to 32.7 %, and passed UL-94V-0 rating. In comparison to the controls, the peak heat release rate and the peak smoke release rate were 88.5 % and 80 % lower, respectively. In addition, PP samples showed improved mechanical properties, with a 5 % increase in tensile properties compared to the pure PP sample. After 100 h of UV irradiation, the surface of the samples was relatively flat and smooth, and the carbonyl index decreased from 81.1 of neat PP to 26.7. PP composites with 100 h aging treatment still had excellent flame retardancy and mechanical properties. The results showed that mZnO was effective in improving the flame retardancy, mechanical properties and light aging tolerance of PP. This study provides a novel approach to fabricate long-life flame-retardant PP composites with low additive content. [ABSTRACT FROM AUTHOR]

In this paper, flame retardant composites were prepared by incorporating three flame retardants (FRs), including triphenyl phosphate (TPP), polysiloxane (PSQ) and phosphite functionalized polysiloxane (PPSQ), respectively into a polylactic acid (s/PLLA) matrix. The results indicated that the ultimate oxygen index increased from 20.6% (s/PLLA) to 22.5% (s/PLLA/TPP), 21.1% (s/PLLA/PSQ), and 23.3% (s/PLLA/PPSQ). The composites exhibited a decrease in peak heat release rate (pHRR) and prolonged peak time according to the cone calorimetry analysis. s/PLLA/PPSQ possessed the highest residual carbon content and the densest char residue with finest and smallest pores, indicating excellent flame-retardant performance. The crystallization behavior analysis revealed that the three FRs resulted in an increased crystallization rate and crystallinity. Notably, the crystallinity of s/PLLA/PPSQ increased from 25.8% in s/PLLA to 37.3%. Additionally, PSQ and PPSQ effectively enhanced the mechanical properties of composite materials. Compared to s/PLLA, the tensile strength of s/PLLA/PSQ and s/PLLA/PPSQ increased by 11.5% and 31.3% respectively, and storage modulus increased by 50.0% and 14.6%. This research demonstrated that among the three additives, PPSQ can effectively provide both flame retardancy and mechanical properties to the s/PLLA matrix, resulting in the composite with the best comprehensive performance. [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]

To meet the environmental protection and flame retardancy requirements for epoxy resins (EPs) in certain fields, in this study, a novel triazine-ring-containing DOPO-derived compound (VDPD), derived from vanillin, 2,4-Diamino-6-phenyl-1,3,5-triazine, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO), was synthesized using a one-pot method. Flame-retardant epoxy resin (FREP) was prepared by adding various ratios of VDPD to EP and curing with 4,4-diaminodiphenylmethane (DDM). The curing behavior, thermal stability, mechanical properties, and flame-retardant properties of the FREP were examined in various tests. According to the results, when the amount of VDPD added to the EP increased, the glass transition temperature of the FREP decreased linearly, and the flame-retardant properties gradually improved. With a 0.4 wt.% P content, the vertical burning rating of EP/DDM/VDPD-0.4 (according to the theoretical content of VDPD) reached the V-0 level, and the LOI value reached 33.1%. In addition, the results of a CCT showed that the peak heat release rate (PHRR) of EP/DDM/VDPD-0.4 decreased by 32% in comparison with that of the EP. Furthermore, compared with those of the EP, the tensile strength of EP/DDM/VDPD-0.4 decreased from 80.2 MPa to 74.3 MPa, only decreasing by 6 MPa, and the tensile modulus increased. Overall, VDPD can maintain the mechanical properties of EP and effectively improve its flame-retardant properties. [ABSTRACT FROM AUTHOR]

Due to the difficulty of absorbing viscous crude oil, there is an urgent need for carbon sponges with excellent photothermal properties and oil‐water separation capabilities to reduce viscosity and facilitate oil absorption. However, the preparation of high‐temperature carbonization leads to poor mechanical properties, low absorption capacity, and stringent preparation conditions. To solve these challenges, a highly hydrophobic flame‐retardant melamine sponge (CPBA@CMS) is designed by assembling sponge at the interface of cobalt–iron Prussian blue (CoFe‐PBA) derived from metal–organic frameworks (MOFs) and conducting low‐temperature catalytic carbonization under nitrogen. The results demonstrate that CPBA@CMS exhibits excellent superhydrophobic properties (water contact angle = 169.7°) and oil absorption capacity (80.7–219.5 g g−1). Furthermore, CPBA@CMS displays remarkable photothermal effects and thermal conductivity, making it adaptable to various environmental conditions. It can rapidly rise to 141 °C under 1 kW m−2 solar irradiation, with the maximum oil absorption rate reaching 98% and the highest oil absorption capacity at 105.5 g g−1. Additionally, CPBA@CMS shows significant fire safety performance, reducing heat release rate by 84.2%, smoke factor by 97.5%, and CO release rate by 81.4%, respectively. It provides an efficient, safe, and sustainable practical solution for effectively addressing spills of crude oil. [ABSTRACT FROM AUTHOR]

The first step in current methodologies for the (probabilistic) performance-based fire safety design and assessment of structures is characterizing fire hazard scenario(s). Next, structural response analysis is performed to estimate hazard consequences in terms of damage or loss metrics of interest. These metrics are eventually appraised to verify whether various performance objectives are achieved and design iterations are needed. Nevertheless, such approaches rely on preliminary assumptions on the structural configuration and features characterizing scenarios used as thermal inputs. Consequently, they do not fully exploit the fire–structure coupling effect, where fire affects a structure, and the characteristics of the structure also affect the combustion process and fire dynamics. Indeed, the structural design choices define the fire scenarios that could potentially affect the structural and nonstructural performance. This paper introduces a consequence-oriented fire intensity optimization (CFO) approach to the fire safety design of structures to address such limitations. The proposed approach considers fire scenarios as additional design variables and delivers them as procedure outputs, optimizing the balance between increasing structural capacity and decreasing fire intensity. Furthermore, it evaluates the effect of input uncertainties through Monte Carlo sampling. A single-span bridge subject to a car fire is used to showcase the proposed approach. For this case study, it is shown that fire scenario characteristics (fuel bed and traffic load positions, heat release rate history) maximizing consequences are strongly correlated to the structural features and cannot be set a priori. Finally, design decisions exploiting the described coupling effect to achieve various performance objectives are discussed. Overall, the proposed approach highlights the benefits of enhancing the fire and heat transfer model's capability to capture the fire–structure coupling effect for achieving more optimized design solutions. [ABSTRACT FROM AUTHOR]

[Display omitted] • P N flame retardant HEPFR can be simply synthesized by supramolecular assembly. • HEPFR has the modification effect of "one stone, three birds" on PVA. • Flame-retardant, transparent and robust PVA film can be easily fabricated. Supramolecular flame retardants have attracted increasing attention recently due to their simple and eco-friendly preparation process. In this study, a novel flame retardant HEPFR was prepared using supramolecular self-assembly technology between piperazine and 1-hydroxy ethylidene-1,1-diphosphonic acid (HEDP). It was introduced into polyvinyl alcohol (PVA) matrix to form PVA/HEPFR composite film. Subsequently, the transparency, mechanical properties, thermal stability, and flame retardancy of PVA/HEPFR films were studied. Due to the hydrogen bonded cross-linked network structure between PVA and HEPFR, the mechanical properties of PVA/HEPFR films have been improved, while maintaining good transparency. With 10 wt% addition of HEPFR, PVA films can reach the VTM-0 level in UL-94 testing. And the limiting oxygen index can be increased from 18.5% of pure PVA to 26.5%. The peak heat release rate was reduced by 61.5%. The flame retardancy and thermal stability of PVA/HEPFR films have been greatly improved. This study provides a "one stone, three birds" strategy for preparing flame-retardant, transparent, and robust PVA film. [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]

In this study, in order to expand the engineering application range of thermoplastic corrugated sheets, flame-retardant thermoplastic corrugated sheets were prepared by the thermoplastic molding method. Based on our previous research results, we prepared flame-retardant prepreg tapes with the flame retardant addition accounting for 15%, 20%, and 25% of the resin matrix. Then, we prepared flame-retardant thermoplastic corrugated sandwich panels with corresponding flame retardant addition amounts. The limiting oxygen index test, vertical combustion test, cone calorimetry test, and mechanical property test were carried out on each group of samples and control group samples. The results showed that when the flame retardant was added at 25%, the flame retardant level could reach the V0 level. Compared with the control group, the flexural strength and flexural modulus decreased by 2.6%, 14.1%, and 19.9% and 7.3%, 16.1%, and 21.9%, respectively. When the amount of flame retardant was 15%, 20%, and 25%, respectively, the total heat release decreased by 16.3%, 23.5%, and 34.1%, and the maximum heat release rate decreased by 12.5%, 32.4%, and 37.4%, respectively. [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]

Polyurethane (PUR), as an engineering polymer, is widely used in many sectors of industries. However, the high fire risks associated with PUR, including the smoke density, a high heat release rate, and the toxicity of combustion products limit its applications in many fields. This paper presents the influence of silsesquioxane fillers, alone and in a synergistic system with halogen-free flame-retardant compounds, on reducing the fire hazard of polyurethane foams. The flammability of PUR composites was determined with the use of a pyrolysis combustion flow calorimeter (PCFC) and a cone calorimeter. The flammability results were supplemented with smoke emission values obtained with the use of a smoke density chamber (SDC) and toxicometric indexes. Toxicometric indexes were determined with the use of an innovative method consisting of a thermo-balance connected to a gas analyzer with the use of a heated transfer line. The obtained test results clearly indicate that the used silsesquioxane compounds, especially in combination with organic phosphorus compounds, reduced the fire risk, as expressed by parameters such as the maximum heat release rate (HRRmax), the total heat release rate (THR), and the maximum smoke density (SDmax). The flame-retardant non-halogen system also reduced the amounts of toxic gases emitted during the decomposition of PUR, especially NOx, HCN, NH3, CO and CO2. According to the literature review, complex studies on the fire hazard of a system of POSS–phosphorus compounds in the PUR matrix have not been published yet. This article presents the complex results of studies, indicating that the POSS–phosphorous compound system can be treated as an alternative to toxic halogen flame-retardant compounds in order to decrease the fire hazard of PUR foam. [ABSTRACT FROM AUTHOR]

Intumescent flame retardants (IFRs) are mainly composed of ammonium polyphosphate (APP), melamine (ME), and some macromolecular char-forming agents. The traditional IFR still has some defects in practical application, such as poor compatibility with the matrix and low flame-retardant efficiency. In order to explore the best balance between flame retardancy and mechanical properties of flame-retardant polyformaldehyde (POM) composite, a biobased calcium magnesium bi-ionic melamine phytate (DPM) synergist was prepared based on renewable biomass polyphosphate phytic acid (PA), and its synergistic system with IFRs was applied to an intumescent flame-retardant POM system. POM/IFR systems can only pass the V-1 grade of the vertical combustion test (UL-94) if they have a limited oxygen index (LOI) of only 48.5%. When part of an IFR was replaced by DPM, the flame retardancy of the composite was significantly improved, and the POM/IFR/4 wt%DPM system reached the V-0 grade of UL-94, and the LOI reached 59.1%. Compared with pure POM, the PkHRR and THR of the POM/IFR/4 wt%DPM system decreased by 61.5% and 51.2%, respectively. Compared with the POM/IFR system, the PkHRR and THR of the POM/IFR/4 wt%DPM system were decreased by 20.8% and 27.5%, respectively, and carbon residue was increased by 37.2%. The mechanical properties of the composite also showed a continuous upward trend with the increase in DPM introduction. It is shown that the introduction of DPM not only greatly reduces the heat release rate and heat release amount of the intumescent flame-retardant POM system, reducing the fire hazard, but it also effectively improves the compatibility between the filler and the matrix and improves the mechanical properties of the composite. It provides a new approach for developing a new single-component multifunctional flame retardant or synergist for intumescent flame-retardant POM systems. [ABSTRACT FROM AUTHOR]

To ensure fire safety, polymers are filled with flame retardants and smoke suppressants. To meet the highest requirements, it is essential to understand the decomposition of those polymeric materials. This study reveals interactions between polymer, smoke suppressants, and flame retardants, and discusses their impact on the materials' flame retardancy, smoke emission, smoke toxicity, and particle emission in conventional loadings to provide deeper general understanding. Low melting oxide glass, melem, spherical silica, sepiolite, melamine polyphosphate, and boehmite in an aluminum diethylphosphinate flame-retarded polyamide 6.6 were investigated. All smoke suppressants improve the protective layer and act as an adjuvant. Silica and melem performed best under forced flaming conditions. Spherical silica reduces the peak of heat release rate by 39% and the total heat evolved by 14%, whereas 10 wt% melem lowers the total smoke production by 41%. Melem alters the mode of action of aluminum diethylphosphinate from gas to more condensed phase activity. This change reduces flame inhibition and hence smoke toxicity, but further improves the protective layer due to charring reactions in the decomposition mechanism. In addition, the sizes of the smoke particles decrease because of the prolonged time in the pyrolytic zone. This study highlights that interactions between polymer, flame retardants, and smoke suppressants can significantly determine the smoking and burning behavior. [ABSTRACT FROM AUTHOR]

Aluminum butylmethylphosphinate AiBMP as a flame retardant and phenolphthalein as a synergistic agent were applied in a thermoplastic polyester elastomer (TPEE)) in the current study. The thermal properties, flame retardancy, crystallization and mechanical properties of TPEE/AiMBP with or without phenolphthalein were investigated using various characterizations, including the limiting oxygen index (LOI), vertical burning test (UL 94), thermogravimetric analysis TG, differential scanning calorimetry, microcombustion calorimeter (MCC), scanning electron microscopy (SEM), and mechanical tests. The results revealed that AiBMP alone is an efficient flame retardant of TPEE. Adding 15 wt.% AiBMP increases the LOI value of TPEE from 20% to 36%. The formula TPEE-15 AiBMP passed the UL 94 V-0 rating with no dripping occurring. The MCC test shows that AiBMP depresses the heat release of TPEE. In comparison with pure TPEE, the heat release rate at peak temperature and the heat release capacity of TPEE-15AiBMP are reduced by 46.1% and 55.5%, respectively. With the phenolphthalein added, the formula TPEE/13AiBMP/2Ph shows a higher char yield at high temperatures (>600 °C), and the char layer is stronger and more condensed than TPEE-15AiBMP.The tensile strength and elongation at break values of TPEE-13AiBMP-2Ph are increased by 29.63% and 4.8% in comparison with TPEE-15AiBMP. The SEM morphology of the fracture surface of the sample shows that phenolphthalein acts as a plasticizer to improve the dispersion of AiBMP within the matrix. The good char charming ability of phenolphthalein itself and improved dispersion of AiBMP make the TPEE composites achieve both satisfying flame retardancy and high mechanical properties. [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]

Consideration of appropriate fire scenarios in the simulations of the Fire Dynamics Simulator (FDS) for the fire-risk assessment of buildings is a critical factor in the development of prevention and response measures. The user dependence of the FDS input parameters can threaten the reliability of the fire-risk assessment. An experimental study was conducted to establish correlations for considering appropriate fire scenarios using polymethyl methacrylate. To examine the changes in the maximum-heat-release rates (HRRs) according to the combustion environment, nine burners varying in size at 25 mm intervals were burned in open and compartment environments. The results indicated that compared with the fire phenomenon in the open environment, the maximum HRR and fire growth rate of the compartment fire were increased by factors of 3–50. Additionally, the compartment fire phenomena could be classified into three stages according to the changes in the aforementioned two physical quantities. An analysis of the experimental results revealed a correlation for predicting the maximum HRR of a compartment fire with various ventilation conditions using only the experimental results for the open environment. The maximum HRR predicted through this correlation exhibited an error of <15% relative to the values measured in the experiment. [ABSTRACT FROM AUTHOR]

This document is an editorial from the journal Molecules titled "Advances in Novel Flame-Retardant Technologies for Fire-Safe Polymeric Materials." It discusses recent developments in the design and preparation of flame retardants for use in fire-safe polymeric materials. The article highlights the four stages of development in flame-retardant polymeric materials and emphasizes the importance of eco-friendly and sustainable technologies. The document includes seven original research contributions and four review articles covering various aspects of fire-safe polymeric materials, such as epoxy resins, rigid polyurethane foams, vinyl ester resins, and textiles. The authors conclude that further progress is needed to transfer these technologies from research to industry. [Extracted from the article]

Unsaturated polyester resin (UPR) with excellent flame retardant is mainly obtained by adding large amounts of flame retardants, usually at the expense of mechanical properties. In this work, a reactive flame retardant containing phosphorus and nitrogen (DOPO-N) was successfully synthesized and incorporated in UPR as a crosslinker. The mechanical and flame-retardant properties of UPR composites were enhanced. UPR/30DOPO-N passed a UL-94 V-1 rating with a limiting oxygen index (LOI) of 30.8%. The tensile strength of UPR/30DOPO-N increased by 24.4%. On this basis, a small amount of modified HNTs (VHNTs) was added to further improve the flame-retardant properties of the composite. With the introduction of 3 wt% VHNTs, the composite passed the UL-94 V-0 rating. The peak of heat release rate (PHRR) and total heat release (THR) of it decreased by 60.7% and 48.3%, respectively. Moreover, the detailed flame-retarding mechanism of DOPO-N and VHNTs was investigated by thermogravimetric infrared spectroscopy (TG-IR), Raman spectra, and X-ray photoelectron spectroscopy (XPS). It was found that DOPO-N played a role in quenching the flame in the gas phase and cooperated with VHNTs to enhance the barrier effect in the condensed phase. [ABSTRACT FROM AUTHOR]

In this work, a thermal behaviour comparison of a new bamboo-based and banana-based Green Bio-Composites (GBC) is conducted using thermogravimetric analysis (TGA) and cone-calorimeter experiments. An Intumescent Fire-Retardant (IFR) coating (a mixture of Exolit IFR36 and boric acid) has been applied on the investigated GBC materials in order to explore the flammability resistance of such GBCs. Vacuum Bag Resin Transfer Moulding (VBRTM) technique has been used to manufacture the samples. TGA test have been conducted under oxidative atmosphere with three different heating rates while cone calorimeter tests have been performed with a horizontally exposure on the top surface of the sample. The outcomes of TGA revealed that Bamboo-based (BM-GBC) and Banana-based (Bn-GBC) materials exhibited similar thermal degradation patterns. However, BM-GBC outperformed Bn-based in the cone calorimetry analysis, this is proven by the fire reaction parameters as well as the higher char residue. In addition, IFR coating improved the flame retardancy of both GBCs, reduced the Peak Heat Release Rate (PHRR) by approximately 40–50% and smoke production (SEA) by 26%. SEM and EDS analysis of char residue were performed to deeply investigate the effectiveness of the IFR as a protecting layer. [ABSTRACT FROM AUTHOR]

The epoxy resin-based (ESB) intumescent flame-retardant coatings were modified with 1,4-butanediol diglycidyl ether (14BDDE) and butyl glycidyl ether (BGE) as diluents and T403 and 4,4′-diaminodiphenylmethane (DDM) as curing agents, respectively. The effects of different diluents and curing agents on the flame-retardant and mechanical properties, as well as the composition evolution of the coatings, were investigated by using large-plate combustion, the limiting oxygen index (LOI), vertical combustion, a cone calorimeter, X-ray diffraction, FTIR analysis, a N2 adsorption and desorption test, a scanning electron microscope (SEM), a tensile strength test, and a viscosity test. The results showed that the addition of 14BBDE and T403 promoted the oxidation of B4C and the formation of boron-containing glass or ceramics, increased the residual mass of char, densified the surface char layer, and increased the specific surface area of porous residual char. When their dosage was 30%, ESB-1T-3 coating exhibited the most excellent flame-retardant properties. During the 2 h large-plate combustion test, the backside temperature was only 138.72 °C, without any melting pits. In addition, the peak heat release rate (PHRR), total heat release rate (THR), total smoke production (TSP), and peak smoke production (PSPR) were reduced by 13.15%, 13.9%, 5.48%, and 17.45%, respectively, compared to the blank ESB coating. The LOI value reached 33.4%, and the vertical combustion grade was V-0. In addition, the tensile strength of the ESB-1T-3 sample was increased by 10.94% compared to ESB. In contrast, the addition of BGE and DDM promoted the combustion of the coating, affected the ceramic process of the coating, seriously affected the formation of borosilicate glass, and exhibited poor flame retardancy. The backside temperature reached 190.93 °C after 2 h combustion. A unified rule is that as the amount of diluent and curing agent increases, the flame retardancy improves while the mechanical properties decrease. This work provides data support for the preparation and process optimization of resin-based coatings. [ABSTRACT FROM AUTHOR]

[Display omitted] The creation of high-performance thermal insulation and flame-retardant materials is of great importance for minimizing energy consumption and reducing fire risk for modern buildings. Herein, we report the creation of a new composite aerogel, which was prepared by incorporation of 9,10-Dihydro-9-oxa-10-phosphaphenanthrene 10-Oxide-3-Aminopropyl triethoxysilane (DOPO-KH550) modified hollow glass microspheres (HGM) into polyvinyl alcohol (PVA) using citric acid as a cross-linker, as a kind of thermal insulation and flame retardant materials (abbreviated as PVA-DKHGM). The as-synthesized PVA-DKHGM composite exhibits superior thermal conductivity of 0.0187 W m−1 K−1, owing to the hollow structure of the hollow glass microspheres and rich porosity. Besides, it reaches V-0 level at the UL-94 test and the peak heat release rate (pHRR) was measured to be 114.93 (kW/m2) which is lower than most composites now. These results are attributed to the synergy effect of the hollow glass microsphere and DOPO-KH550 which offers the composites aerogel excellent flame retardancy. Owing to its advantages such as lightweight, highly porous, thermally stable, simple to prepare, high mechanical strength, and can be further scaled up, our PVA-DKHGM aerogel may hold great potential for practical applications in construction of energy-saving modern buildings. [ABSTRACT FROM AUTHOR]

[Display omitted] • A core-shell structured piperazine pyrophosphate microcapsules (MT@PAPP) is constructed. • The MT@PAPP enhances the compatibility and mechanical property of TPE/MT@PAPP composites. • Compared with pure TPE, the PHRR and PSPR of TPE/MT@PAPP were reduced by 78.5% and 60.0%, respectively. In this study, core-shell structured piperazine pyrophosphate (PAPP) is designed to enhance the fire safety and mechanical property of styrenic thermoplastic elastomer (TPE) composites. The PAPP is microencapsulated with carbon nanotube modified melamine-formaldehyde resin to prepare core-shell structured flame retardants (MT@PAPP). Due to the excellent compatibility between the MT@PAPP and TPE matrix, the mechanical property of TPE/MT@PAPP is improved. Compared with TPE, the peak heat release rate and peak smoke production rate of TPE/MT@PAPP are decreased by 78.5% and 60.0%, respectively. Thus, the core-shell structured piperazine pyrophosphate microcapsule strategy provides an excellent approach to obtain high-performance TPE composites. [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]

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]

Silica-coated limestone (SCL) microcapsule was synthesized and successfully introduced into acrylic resin to produce fire-retardant coatings. SCL microcapsules were prepared by encapsulating limestone granules with silica nanoparticles using epoxy resin as a binder. The morphology and the chemical composition of the SCL microcapsules were confirmed by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FTIR), respectively. The performance of SCL microcapsules on mechanical, flame retardant and thermal stability of the coatings was thoroughly investigated using FTIR, SEM, thermogravimetric analysis (TG), smoke density test, adhesion pull-off test, pendulum damping test and cone calorimeter test. The results shows that while the adhesion strength, pendulum hardness and limiting oxygen index (LOI) increased remarkably, the values of flame spread ratings (FSR), specific optical density (ODs), heat release rate (HRR), total heat release rate(THRR), smoke production rate (SPR) and total smoke production rate (SPR) decreased significantly with the introduction of SCL microcapsules. The TGA results confirm that incorporation of SCL microcapsules increases the thermal stability and boosts formation of large char layers. [ABSTRACT FROM AUTHOR]

Purpose: This paper aims to study a new halogen-free fame-retardant curing agent 1-aminoethylidenediphosphonate (AAEDP). Design/methodology/approach: The AAEDP was synthesized by phosphoric acid, acetonitrile and ammonia. The chemical structures of AAEDP were characterized by proton nuclear magnetic resonance, mass spectrometry and Fourier transform infrared spectrometer. Thermal gravimetric analysis (TGA) and scanning electron microscope (SEM) would study the thermal properties and the char residues of AAEDP/EP. The thermal stability, mechanical and flame properties and morphology for the char layer of composite materials were separately investigated using TGA, tensile and charpy impact tests, limiting oxygen index (LOI), UL-94 HB flammability standard (UL-94) and SEM. Findings: The results showed that the AAEDP had been prepared successfully. When the intumescent flame retardant was added into the EP, the LOI of composite material was improved. Research limitations/implications: The AAEDP can be prepared successfully and can improve the flame resistance of composite material. Practical implications: The AAEDP has excellent flame-retardant properties and produce no toxic fumes when burnt in case of fire. Originality/value: The results showed that the phosphorus content of AAEDP was 2.958 Wt.%; the impact and tensile strength of the composite material were 6.417 kJ m−2 and 38.0 MPa, respectively; and the LOI and UL-94 were 29.7% and V-0 ranking, respectively. The TGA results indicated that the carbon residue ratio can be increased by 1000°C in air. The denser and more uniform structure of residual carbon prevents heat transfer and diffusion, restricts the production of combustible gas and reduces the rate of heat release. [ABSTRACT FROM AUTHOR]

This study focuses on the increased risk of high heat release and asphyxiation (toxic gas poisoning) in the event of a fire involving polyurethane (PU)- and MDF-based building materials, which are commonly used in buildings. Among them, polyurethane (PU) building materials are very commonly used in buildings, except in Europe and some other countries, due to their excellent thermal insulation performance. Still, problems of short-term heat release and the spread of toxic gases in the event of a fire continue to occur. To overcome these problems, researchers are actively working on introducing various flame retardants into building materials. Therefore, in this study, we produced a laboratory-sized (500 mm × 500 mm) plate-like flame-retardant board that can be utilized as a building material with a lower heat release rate and a lower toxicity index. The material was made by mixing expanded graphite and ceramic binder as flame retardants in a material that is formulated based on the cellulose of waste paper, replacing the existing building materials with a hot-press method. According to the ISO-5660-1 test on the heat release rate of the plate-like flame-retardant board, the Total Heat Release (THR) value was 2.9 (MJ/m2) for 10 min, showing an effect of reducing the THR value by 36.3 (MJ/m2) compared to the THR value of 39.2 (MJ/m2) of the specimen made using only paper. In addition, the toxicity index of the flame-retardant board was checked through the NES (Naval Engineering Standards)-713 test. As a result, the test specimen showed a toxicity index of 0.7, which is 2.4 lower than the toxicity index of 3.1 of MDF, which is utilized as a conventional building material. Based on the results of this study, the cellulose fire-retardant board showed the effect of reducing the heat release rate and toxicity index of building materials in a building fire, which reduces the risk of rapid heat spread and smoke toxicity. This has the potential to improve the evacuation time (A-SET) of evacuees in fires. It is also important to show that recycling waste paper and utilizing it as the main material for building materials can be an alternative in terms of sustainable development. [ABSTRACT FROM AUTHOR]

Lignin was utilized as an environmentally friendly synergistic agent to augment the fire resistance and mechanical characteristics of rigid polyurethane foam (PUF)/melamine–formaldehyde resin ammonium polyphosphate (MFAPP). The incorporation of lignin significantly enhanced the charring capability and flame retardancy of PUF/MFAPP. Specifically, PUF/MFAPP12/A-lignin3 exhibited a charring residue of 23.1% at 800 °C, accompanied by an increase in the limiting oxygen index (LOI) to 23.1%, resulting in a UL-94 V-0 rating. The cone calorimeter test (CCT) revealed that the peak heat release rate (PHRR), total heat release (THR), smoke production rate (SPR), and total smoke production (TSP) values of PUF/MFAPP12/A-lignin3 were all lower than for pure PUF. MFAPP and alkali lignin exerted a noticeable influence on the physical and mechanical properties, leading to increases in density (35.4 kg/m3), thermal conductivity (32.68 mW/(m·K)), and compressive strength (160.5 kPa). Observations of the morphology and elemental composition of char residues after combustion indicated the formation of an intact, thick, and continuous char layer enriched with nitrogen and phosphorus elements, which acted as a protective shield for the underlying foam. [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]

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]

[Display omitted] • MXene-coated cotton composites were prepared via dip coating method. • Cotton/TPU hierarchical composites were prepared by air assisted hot pressing. • Superior fire safety, EMI shielding and mechanical properties were obtained. • Multiple interface interactions are responsible for properties improvements. Cotton fabric composites were designed to be protected by fire safe thermoplastic polyurethane (TPU) composites for developing electromagnetic interference (EMI) shielding polymer composites with superior mechanical properties. Herein, the as-prepared MXene was coated onto the fiber surface of cotton and then thermally compressed with TPU composites, which were filled with the sodium dodecyl sulfate modified layered double hydroxides functionalized the short carbon fiber hybrids through melt blending method. Then, a series of highly fire safe cotton/TPU hierarchical composites were constructed by a designed thermal compression technique. For instance, the obtained cotton/TPU hierarchical sample showed greatly reduced peak of heat release rate, peak of carbon monoxide production rate and peak of carbon dioxide production rate of TPU by 50.1%, 52.1% and 55.4%, respectively. Furthermore, the cotton/TPU hierarchical composites possessed the EMI shielding effectiveness of 40.0 dB in the X band and 54.6 dB in the K band. The mechanical property of the cotton/TPU hierarchical composites was also reinforced, where the elongation at break and toughness values of the TPU/SCF/mLDH1/ C 2 hierarchical composite were 21.47 and 18.30 times higher than those of pure TPU, respectively. These mechanically strong hierarchical composites have brought a promising attempt to broaden their practical application, removing the fire hazards and electromagnetic waves radiation from the environment. [ABSTRACT FROM AUTHOR]

In this study, rigid polyurethane foams modified with non-halogenated flame retardant were obtained. The foams were synthesized using two systems containing different blowing agents. In the first one, cyclopentane and water were used as a mixture of blowing agents, and in the second one, only water was used as a chemical blowing agent. The systems were modified with the additive phosphorus flame retardant Roflam F5. The obtained modified foams were tested for their flammability and basic properties, such as apparent density, closed-cell contents and analyses of the cell structures, thermal conductivity, mechanical properties, and water absorption. Increasing the content of Roflam F5 caused a decrease in temperature during the combustion of the material and extended the burning time. The addition of 1.0 wt.% phosphorus derived from Roflam F5 caused the modified rigid polyurethane foam to become a self-extinguishing material. The increase in the content of Roflam F5 caused a decrease in the total heat release and the maximum heat release rate during the pyrolysis combustion flow calorimetry. The foams with the highest content of flame retardant and foamed with a chemical-physical and chemical blowing agent had a lower total heat release by 19% and 11%, respectively, compared to reference foams. [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]

It is well known that rare earth elements have the potential for enhancing the flame retardancy of polymer materials. Herein, a novel 0D/2D structure of cerium stannate (Ce2Sn2O7) hybridized with molybdenum disulfide (CSO@MoS2) was synthesized by an in situ co-precipitation method. The structure and morphology of the CSO@MoS2 hybrid were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), and transmission electron microscopy (TEM). The effects of the CSO@MoS2 hybrid on the fire safety properties of epoxy resin (EP) were investigated. The scanning electron microscopy (SEM) results showed the CSO@MoS2 hybrid achieved a desired dispersion in EP composites and endowed outstanding thermal stability and flame retardancy to the EP. The EP/CSO@MoS2 composites exhibited 27%, 31%, 28%, 35%, 40%, and 29% reductions in the peak heat release rate (PHRR), total heat release (THR), peak smoke release rate (PSPR), total smoke release (TSP), peak CO production rate (PCO), and peak CO2 production rate (PCO2), respectively, compared with those of neat EP. The improved fire safety performance of the EP composites was attributed to the catalytic carbon formation ability of the rare earth elements and the physical barrier effect of the MoS2 nanosheets. This provides a simple and efficient strategy for the utilization of rare earth resources in ensuring the fire safety of EP composites. [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 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]

The phosphorous‐based flame retardant additives poly(m‐phenylene methylphosphonate) (PMP) and resorcinol bis(diphenyl phosphate) (RDP) are reacted with bisphenol F and aniline–based benzoxazine (BF‐a). DSC, rheological analysis, FT‐IR, and soxhlet extraction reveal the covalent incorporation of both FR additives—initiating phenols in PMP structure as well as free phenols generated via transesterification reaction in the case of RDP. In contrast to PMP, RDP elongates the processing window but decreases the thermo–mechanical properties. Both additives increase the resistance in reactions against small flames with solely a phosphorous loading of 0.3 wt%, resulting in a V‐0 rating and an improvement in the OI value by up to 2% for RDP and 4% for PMP. Both FRs reduce the heat release rate but increase the smoke production and the smoke toxicity in the case of RDP. [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]

In this work, an effective flame retardant consisting of nanoscale zinc oxide doped on the surface of hexagonal lamellar magnesium hydrate (ZO@MH) has been successfully synthesized via a hydrothermal process. Approximately 3-methacryloxypropyltrimethoxysilane (KH-570) is chosen as a modifier of ZO@MH for the purpose of enhancing the interfacial interaction between ZO@MH and the polypropylene (PP) matrix and reducing the agglomeration of ZO@MH. Afterwards, ZO@MH and KH-570 modified ZO@MH (KZO@MH) filled PP (PP/ZO@MH and PP/KZO@MH) composites are respectively prepared via the melt blending method. The flame retardant and smoke suppression properties of PP/ZO@MH and PP/KZO@MH composites are estimated by a cone calorimetry test (CCT). The peak value of the heat release rate of the PP/40KZO@MH composite is 327.0 kW/m2, which is 6.1% and 31.2% lower than that of the PP/40ZO@MH and PP/40MH composites, respectively. The lowest peak values of CO and CO2 production, 0.008 and 0.62 g/s, also appeared in the PP/40KZO@MH composite, which are 11.1% and 10.1% lower than those of the PP/40ZO@MH composite. Analysis of char residues indicates that nanoscale ZO and modification of KH-570 improve the amount and quality of char residues, which should be the main reason for the good flame retardant and smoke suppression properties of KZO@MH. Impact strength and nominal strain at break results show that the PP matrix is toughened by ZO@MH rather than KZO@MH. Tensile properties and the quantitative interfacial interaction calculated by the Turcsányi equation both prove the reinforcement of KZO@MH on the PP matrix. [ABSTRACT FROM AUTHOR]

In this study, flame-retardant poly (butylene succinate) (PBS) composites were developed utilizing a bio-based intumescent flame retardant (IFR) system. Water hyacinth fiber (WHF) was used as a bio-based carbon source, while ammonium polyphosphate (APP) served as both an acid source and a blowing agent. Effects of WHF:APP weight ratio and total IFR content on the thermal stability and flammability of WHF/APP/PBS composites were investigated. The results demonstrated that the 15WHF/30APP/PBS composite with a WHF to APP ratio of 1:2 and a total IFR content of 45 wt% had a maximum limiting oxygen index (LOI) value of 28.8% and acquired good flame retardancy, with a UL-94 V-0 rating without polymer-melt dripping. Additionally, its peak heat release rate (pHRR) and total heat release (THR) were, respectively, 53% and 42% lower than those of the neat PBS. Char residue analysis revealed that the optimal WHF:APP ratio and total IFR content promoted the formation of a high graphitized intumescent char with a continuous and dense structure. In comparison to the neat PBS, the tensile modulus of the 15WHF/30APP/PBS composite increased by 163%. Findings suggested the possibility of employing WHF, a natural fiber, as an alternative carbon source for intumescent flame-retardant PBS composites. [ABSTRACT FROM AUTHOR]

To gain insight into more about how flame retardants containing phosphorus, sulfur, and nitrogen affect epoxy resin (EPs), a multicomponent flame retardant (Sp-ACDH) containing P/N/S was synthesized from sodium p-aminobenzene sulfonate (Sp-A), cinnamaldehyde and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and applied to epoxy resin. Sp-ACDH enables the epoxy resin to achieve the desired flame retardancy. For example, with the addition of 10 wt% Sp-ACDH, the epoxy composite passed the UL-94 V-0 rating and achieved an LOI of 32.7%. Additionally, Sp-ACDH effectively slowed down EP's ability to release heat, with EP-15 Sp-ACDH exhibiting a peak heat release rate (PHRR) that was 680 kW/m2 rather than pure EP's 1204.4 kW/m2. Eventually, the samples were characterized using Scanning electron microscopy (SEM), Raman spectroscopy, and Thermogravimetric analysis-fourier transform infrared spectroscopy (TG-FTIR) spectra, and the samples were analyzed, it revealed that Sp-ACDH's flame-retardant properties were active in both the gas and condensed phases. [ABSTRACT FROM AUTHOR]

Flame retardant treatment of epoxy resins (EP) to reduce their flammability for extending their range of applications attracts considerable attention. However, the synthesis process of conventional flame retardants is complicated and involves organic hazardous solvents. Meanwhile, how to ensure both the flame‐retardant and mechanical properties is a long‐standing and actual difficult problem. In this work, a supramolecular flame retardant (named ATPFR) is facilely created by one‐pot reaction, using cheap and accessible raw materials in an ecologically benign aqueous solvent. ATPFR is applied to improve the fire safety of EP. With only 5 wt% ATPFR addition, EP can reach the limiting oxygen index of 28.5% and the UL‐94 V‐0 rating with a significant "blow‐out effect." The cone calorimetry test reveals that the EP thermoset with 5 wt% ATPFR has a 75.8% reduction in the peak heat release rate (p‐HRR) and a 67.3% reduction in the peak smoke production rate (p‐SPR), respectively, compared with the pure EP. Additionally, EP composites with the small amount of ATPFR exhibit a slight decrease and maintain good mechanical properties. Therefore, the facile synthesis and application of this supramolecular flame retardant provide a reliable way for the construction of polymer materials with environment‐friendly and effective flame‐retardant system. [ABSTRACT FROM AUTHOR]

A triazine long chain charring agent (TCA) was synthesised using cyanuric chloride, morpholine and anhydrous piperazine. The synthesised TCA was compounded with ammonium polyphosphate (APP) to obtain an intumescent flame retardant (IFR). When the TCA content in the IFR was 35 wt% to 45 wt%, the IFR had good expansion properties. Then, different proportions of IFR were incorporated into polypropylene (PP) to prepare flame retardant PP composites, and the flame retardancy, thermal degradation behaviour and flammability behaviour for PP composites were investigated by limiting oxygen index (LOI), vertical burning test (UL-94) and cone calorimeter test. When 20 wt% of IFR (With TCA 35 wt%) were added into the PP matrix, the composite achieved a V-0 rating for the UL-94 test and its LOI value was increased to 28.8%. Compared with neat PP, peak heat release rate (PHRR) and total heat release (THR) decreased from 827.30(KW·m−2) and 120.48(MJ·m−2) to 210.50(KW·m−2) and 75.08(MJ·m−2). [ABSTRACT FROM AUTHOR]

Polyurethane elastomers (PUEs) serve a vital role in our daily life and various industrial applications, but their flammability has been proven to be a significant drawback. In this work, we have successfully fabricated two modified gallic acids (GAP and GAN) by simple esterification, both of which are effective flame retardants and cross‐linkers for PUEs. According to thermogravimetric analysis (TGA) and limiting oxygen index (LOI) tests, the introduction of GAP and GAN conspicuously improves the char yield (4.9~5.8 wt.%) and LOI value of PUEs (33~35 %). The cone calorimetry tests suggest that the peak heat release rate (PHRR) and total heat release (THR) of PUE decrease significantly, while the fire performance index (FPI) value increase after GAP or GAN modification. Both GAP and GAN enhance the density and strength of carbon residues, and inhibit the generation of combustible volatile gas during the combustion process, thereby improving the fire safety of PUEs. In addition, both GAP and GAN contain multiple benzene rings and hydrogen bonding, which can improve the cross‐linking density of PUEs to enhance their mechanical properties (the elongation at break: 844~951 %; tensile strength: 6.37~8.13 MPa). [ABSTRACT FROM AUTHOR]