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Fireproof sealant is a common sealing material and has a wide range of applications, which has the dual performance of sealing and fireproof. To figure out its thermal degradation behavior, the thermogravimetric experiments combined with Fourier transform infrared technology were conducted at multiple heating rates. The results showed that the pyrolysis process could be separated into three stages and the explicit reaction equations were revealed corresponding to each stage: First, ammonium polyphosphate decomposed to produce a large amount of inorganic acid, along with a small amount of ammonia and water. Then, a large amount of ammonia gas was produced from melamine decomposition, and the substrate including acrylic resin began to react. Furthermore, the remaining base materials and intermediate carbonized materials continued to be decomposed to produce large amounts of carbon dioxide, water and residue. The experimental results indicated that the various components of fireproof sealant could cooperate closely and played a synergistic role in flame retardant, which could be an important reference value for guiding the improvement of fire sealing materials. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel and simple scheme for loading aluminum hypophosphite on MOF derivatives. • The dual function of carboxymethyl cellulose: buffer and support layer. • The double-layer hollow nano hybrid is integrated with multiple flame retardant elements. • The flame retardancy of epoxy resin composites is significantly improved after the introduction of AHP/ACP@CMC due to its unique components and nanostructure. Aluminum hypophosphite (AHP) has been used as a flame retardant for a long time. Previous studies about AHP employed in flame retardant materials mostly focus on coating, modification, and complex system. It is valuable to explore simple experimental steps to prepare nano hybrids with AHP and metal–organic frameworks (MOFs). We found acidic substances could etch zeolitic imidazolate framework-67 (ZIF-67) to obtain MOF derivatives. Unfortunately, AHP and ZIF-67 could not directly form a hybrid. Therefore, carboxymethylcellulose (CMC) is introduced as a dual function layer (buffer and support). The CMC resists the complete conversion of ZIF-67 etched by phosphoric acid to amorphous cobalt phosphate hydrate (ACP). Meanwhile, CMC containing hydroxyl groups combines with AHP through electrostatic interaction and coordination bonds. A double-layer hollow MOF derivative is synthesized through this one-stone-two-birds strategy. Due to multiple flame retardant elements and unique nanostructure, this MOF derivative endows epoxy (EP) resin with excellent flame retardancy. With 2.0 wt% addition, the peak heat release rate (pHRR) and total heat release (THR) of EP/AHP/ACP@CMC are decreased by 47.8 and 21.0 %, respectively. This study proposes a novel scheme that converts AHP into MOF derivatives as high-performance FRs. [ABSTRACT FROM AUTHOR]

To improve the deteriorated performance caused by CO2 release during the curing process of traditional moisture‐crosslinked polyurethane or polyurea and poor flame retardancy, this work realized an effective in situ crosslinking technique triggered by moisture for poly(urethane‐urea) with intrinsic flame retardancy, through the incorporation of trimethoxysilane and phosphorus groups via a continuous two‐stage process. Moisture‐triggered crosslinking reaction of trimethoxysilane groups resulted in the establishment of a robust Si─O─Si network, as confirmed by Fourier transform infrared spectroscopy (FTIR) test. The structure transformation considerably enhanced the material's strength, with the stress at break increasing from 1.0 to 3.2 MPa and modulus from 32.9 to 46.9 MPa. The flame retardant properties of PUUS1 (poly(urethane‐urea) sample) were investigated through limiting oxygen index (LOI) and cone calorimeter (CCT) analysis, demonstrating satisfactory flame resistance, as evidenced by high LOI value of 29%, high char yield of 46.2%, and controlled smoke production. Combining thermogravimetric analysis‐infrared spectrometry (TG‐IR), X‐ray photoelectron spectroscopy (XPS), and flame retardant performance, it is speculated that the generation of phosphorus‐free radical scavengers in gas phase from diethyl bis(2‐hydroxyethyl) aminomethyl phosphonate (DBHAP), coupled with the barrier effects of charred layer and distinctive Si─O─Si framework in condensed phase inhibited combustion and toxic gas emission. The results highlight the successful synthesis of a moisture‐crosslinkable poly(urethane‐urea) with intrinsic flame retardancy, promising for applications necessitating moisture‐crosslinkable materials with superior flame resistance. [ABSTRACT FROM AUTHOR]

With a growing focus on sustainable building thermal regulation for buildings, cellulose foams have emerged as promising materials due to their low thermal conductivity and biodegradable properties. However, their flammability and hygroscopic nature limit practical applications. This is attributed to the abundant hydroxy groups of cellulose. In this study, a sustainable, simple, and cost-effective method was proposed for the synthesis of multifunctional thermal insulation materials based on cellulose nanofiber composite foam with hydrophobic, flame retardant, and thermally insulating performance. As a result, the cellulose nanofiber composite foam showed a high mechanical modulus (6.3 ± 0.3 MPa), high compression strength (0.78 ± 0.10 MPa), and specific modulus (246.2 ± 34.4 MPa·cm3·g⁻1). The homogeneous three-dimensional (3D) porous network structure of cellulose nanofiber composite foam resulted in outstanding thermal insulation capabilities (LOI values of 60.7 ± 3.2, UL-94 V-0 rating) and low thermal conductivity (36.3 ± 0.8 mW·m⁻1 K⁻1). Furthermore, the incorporation of phytic acid (PA) imparted high flame retardancy, while cellulose nanofiber composite foam modified with 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane (POTS) maintained outstanding hydrophobicity (static water contact angle of 145.5° ± 0.2°) even under harsh environmental conditions. In this way, it is believed that cellulose nanofiber composite foam with light weight, high mechanical strength, thermal insulation, high flame retardancy, and hydrophobicity has great potential in thermal insulation materials. [ABSTRACT FROM AUTHOR]

A new strategy for multifunctional coatings with flame retardancy, superhydrophobicity and UV shielding ability on cotton fabrics (SFR cotton) was realized by step-by-step spraying ammonium phytate, lignin and hybrid nanoparticles of polydimethylsiloxane (PDMS) modified mesoporous silica nanoparticles (MSNs) with entrapped Fe2O3 (PDMS@Fe2O3-MSNs). The surface adhesion PDMS@Fe2O3-MSNs constructed micro/nano-scale surface structure on SFR cotton fabric, which endowed superhydrophobic (WCA = 152 ± 1.3°), anti-fouling and self-cleaning properties. Benefiting from the synergistic effects of the physical barrier provided by the PDMS@Fe2O3-MSNs and the intumescent flame-retardant properties of ammonium phytate and lignin, the SFR cotton fabric demonstrated excellent self-extinguishing performance under an open fire and left a char layer with 8.4 cm. In addition, due to the excellent UV-absorption ability of lignin and Fe2O3 nanoparticles, the SFR cotton fabric was able to shield the UV irradiation damages to rat skin. Furthermore, the SFR cotton fabric demonstrated remarkable durability against rigorous conditions, including ultrasonic washing, sandpaper abrasion, UV irradiation and exposure to strong acid/alkali environments. After 150 min of ultrasonic washing and 50 cycles of abrasion, the SFR cotton fabric could preserve its hydrophobicity, flame retardancy and UV shielding ability. In addition, the SFR cotton fabric delivered exceptional chemical stability and UV durability when exposed to strong acid/alkali for 24 h and UV irradiation (200 W) for 12 h, respectively. Significantly, the SFR cotton fabric could retain the original flexibility and breathability of pristine cotton fabric. Therefore, the simple and feasible strategy of multifunctional coatings has broad application prospects in advanced multifunctional textiles, military facilities and other fields. [ABSTRACT FROM AUTHOR]

Green chemicals and their applications to textiles became popular for imparting specific functional properties. Because of their complicated applications, the production of multifunctional textiles consumes high energy and produces high amount of wastewater. Therefore, in this study, an innovative one-step approach was used in order to obtain multifunctional cotton fabrics. Montmorillonite/Ionic Liquid (MMT-IL) nanocomposites were formed by using 3 different ionic liquids [IL1 (1-Methyl-3-butylimidazolium chloride, IL2 (1-Methyl-3- octylimidazolium tetrafluoroborate), and IL3 (1-Methyl-3-octylimidazolium bromide)], at 3 different concentrations determined which were based on the cation exchange capacity (CEC) of the montmorillonite clay mineral and MMT-IL nanocomposites. The synthesized MMT-IL nanocomposites were applied to the cotton fabrics by pad-dry-cure method. The pad-dry-cure process was carried out on fabrics also by using 2 different crosslinkers. Modified ethylene urea (MDEU) and (3-Chloropropyl)trimethoxylane (CPTES) were used as crosslinkers. Structural, thermal and surface properties of the MMT-IL nanocomposites and the treated fabrics were determined by FTIR, XRD, TGA, and SEM–EDS analyses. The performance properties of untreated and MMT-IL nanocomposite-modified fabrics were investigated. In order to determine multifunctional properties, antimicrobial, flame retardancy and conductivity values were examined according to the standards. In addition, whiteness index values were also measured to determine whether the MMT-IL nanocomposite modification affected the appearance properties of the fabrics. The performance properties of the fabrics were detailed by using the Box-Behnken experimental design. This paper describes the synthesis and application of Ionic Liquid-Clay Nanocomposites to cotton fabrics. The IL-MMT treated fabrics gained antimicrobial, flame retardant, and conductive properties. [ABSTRACT FROM AUTHOR]

The flammability of unsaturated polyester resins (UPRs) limits their applications. Herein, a reactive P‐ and N‐containing flame retardant (DPET) having triazole and piperazine rings is reported. The 9,10‐Dihydro‐9‐oxa‐10‐phosphaphenanthrene 10‐oxide (DOPO) was used to introduce P atoms, and eugenol was used to import reactive double bonds to DPET. Different ratios of DPET were mixed with a commercial UPR and the thermal, mechanical, optical, and flame retardancy properties were measured. The addition of 15% of DPET into neat UPR led to a decrease in the water contact angle from 70° ± 2 to 61° ± 2. The gel content values of the UPRs were found to change between 97.5% and 89%. The optical properties of the UPR were adversely affected by the incorporation of DPET. The modulus of the DPET‐containing UPRs increased with increasing amount of DPET and 15% of DPET‐containing UPR displayed a modulus value of 1784 ± 86 MPa. When 15% DPET was added to neat UPR, char yields were increased (from 5.6% to 16.6%). Limiting oxygen index (LOI) values increased with increasing amounts of DPET and reached up to 23.4%. Micro cone calorimeter (MCC) test results showed up to a 20.5% reduction in the peak heat release rate (PHRR) of the UPR when 15% DPET was added. [ABSTRACT FROM AUTHOR]

Although many researchers continue to pursue improved battery capacity, battery safety remains a major concern. The main cause of battery fires is the flammability of the currently available commercial organic liquid electrolytes, which are mainly composed of 1 M lithium hexafluorophosphate (LiPF6) and EC-containing carbonate solvents. Herein, a flame-retardant co-solvent tris(2,2,2-trifluoroethyl) phosphite (TTFP) was applied to improve the flame retardancy of a battery. It could improve the battery's discharging capacities at both 4.2 V and high cut-off voltage (4.5 V). Specifically, at a common voltage of 4.2 V, the cells' 100th discharge capacity without TTFP was 130 mA h g−1 by 0.2C with a capacity retention (CR) of 69%. In comparison, under the same conditions, the capacity of the 10% TTFP-containing cell was 162.3 mA h g−1 with a CR of 73.9%. This increase in the electrochemical properties of the cell is clearly due to the addition of TTFP. When charging and discharging at 2.75–4.5 V, the capacity of the battery with STD after 100 cycles at 0.2C was 118.7 mA h g−1, and the corresponding CR was 60.93%. Meanwhile, the discharged capacity of the battery containing 10% TTFP was 150.0 mA h g−1 with a corresponding CR of 65.39%. Through combustion test with and without the TTFP electrolyte, it can be concluded that the TTFP-containing electrolyte is difficult to ignite. This result indicates that TTFP can efficiently enhance the safety performance of the battery. Thus, the incorporation of TTFP can be beneficial to improve the flame retardancy of the electrolyte. Moreover, TTFP does not affect the electrochemical stability of batteries. Thus, the present work may provide a good direction for the next generation of high-performance and high-safety lithium-ion batteries. [ABSTRACT FROM AUTHOR]

Organic flame retardant 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO) was used to decorate the pores of mesoporous silica (m‐SiO2) nanospheres to prepare a new composite flame retardant (DK‐SiO2). The content of DOPO in DK‐SiO2 is about 17 wt%. Due to the chemical bonding, DK‐SiO2 not only enhances the flame retardant performance, but also effectively avoids adverse effects of DOPO on the glass transition temperature and mechanical properties of epoxy resin (EP). At 9 wt% loading, the limiting oxygen index of the EP increased from 25.7 to 31.2, and successfully passed the UL‐94 V‐0 rating. Besides, DK‐SiO2 can significantly reduce the peak heat release rate, total heat release, and total smoke production of EP, with reductions of 26%, 32%, and 20.8%, respectively. Compared with the simple blended sample, DK‐SiO2 not only has better flame retardant performance but also shows significant advantages in thermodynamic properties. The glass transition temperature, impact, and tensile strength, as well as storage and flexural modulus have been improved. This excellent flame retardant performance is mainly attributed to the gas‐condensed synergistic flame retardant mechanism between DOPO and m‐SiO2. The good thermodynamic performance is due to the excellent dispersion of DK‐SiO2 nanospheres in the EP. [ABSTRACT FROM AUTHOR]

Balancing the enhancement of flame retardancy of epoxy resin while maintaining its mechanical capacities intact poses a significant challenge in the realm of flame‐retardant epoxy resins. To reach the above objectives, a COF‐based synergistic flame retardant with phosphorus, nitrogen, and silicon (PA‐COF@MT) was synthesized using phytic acid (PA), montmorillonite (MT), and covalent organic framework (COF). When PA‐COF@MT was added at 4 wt%, EP/PA‐COF@MT exhibited a reduction of 42.1% in peak heat release rate (PHRR), 45.84% in total heat release (THR), and 59.8% in total smoke production (TSP) compared with the pure EP. LOI increased by 30.5% and UL‐94 tested to V‐0 grade. flame‐retardant index (FRI) value of 3.03, achieving a "good" rating. Fire growth indices and mean effective combustion heat were increased while mechanical properties also improved. These findings suggest that the flame retarding mechanism of PA‐COF@MT is mainly through vapor phase and condensed phase actions. The combined effects of phosphorus, nitrogen, and silicon make the surface of carbon residue solid and dense, resulting in excellent heat insulation and smoke suppression effects. In simple terms, this study provides new insights into COF‐based flame retardants. Combining low‐cost and simple preparation methods, PA‐COF@MT has broad application prospects in flame‐retardant epoxy resin systems. [ABSTRACT FROM AUTHOR]

In order to improve the flame retardancy and smoke suppression of silicone rubber foam (SRF), the CoFe‐LDH was fabricated by coprecipitation method and used as flame‐retardant ingredient in SRF. The influence of CoFe‐LDH on the flame retardancy, combustion behavior, and thermal stability of SRF was investigated. The results demonstrate that SRF containing only 1.0 phr CoFe‐LDH can pass V‐0 rating in the vertical combustion test, with a limiting oxygen index of 28.6%. The total heat release and total smoke production are 22.2% and 61.1% lower than that of SRF, respectively. Moreover, CoFe‐LDH can improve the thermal stability of SRF in the high temperature range, and the char residue at 900°C of SRF/LDH composite is obviously higher than that of pure SRF. In addition, to further understand the flame‐retardant mechanism of CoFe‐LDH, the micromorphology of the char residue and the gaseous products during heating for SRF and SRF/LDH composite were analyzed. The results indicate that CoFe‐LDH exhibits excellent flame‐retardant effects in both condensed and gaseous phases for its functions of catalysis, carbonization, and nonflammable gas release. This study provides a more efficient and convenient strategy for the flame retardant and smoke suppression research of SRF. [ABSTRACT FROM AUTHOR]

As the application of polycarbonate (PC) in various fields continues to expand, the requirements for its flame retardancy are becoming increasingly stringent. To enhance the flame retardancy of PC, employing multi‐element synergistic effects and developing novel flame retardants are considered as vital strategies. This work introduces a blend of 1,3‐Benzenedisulfonic acid dipotassium salt (KSP) and three types of phenyl polysiloxanes, namely Octaphenylcyclotetrasiloxane (P4), Octaphenylsilsesquioxane (OPS), and ladder‐like Polyphenylsesquioxane (L‐PPSQ), into PC to create composites. The thermal stability and combustion properties of these composites were characterized using thermogravimetric analysis (TGA), limiting oxygen index (LOI), UL‐94 vertical burning, and cone calorimetry tests. Composites with phenyl polysiloxanes achieved a UL‐94 V‐0 flame retardant rating for 1.6 mm thickness sample and reduced the peak heat release rate by 30%–45%. PC composites with 3% OPS and 0.03% KSP achieved optimal performance, howing a LOI of 34.5%, a 45.4% reduction in peak heat release, and a 40.5% reduction in total smoke release. The flame‐retardant mechanism was analyzed using scanning electron microscopy (SEM), energy‐dispersive X‐ray spectroscopy (EDX), Fourier transform infrared spectroscopy (FTIR), and pyrolysis‐gas chromatography‐mass spectrometry (Py‐GC‐MS). [ABSTRACT FROM AUTHOR]

Halogen‐free flame‐retardant ethylene‐vinyl acetate/polyethylene/magnesium hydroxide systems are widely used in cable insulations and in sheath materials. The surface modification of magnesium hydroxide is one of the key methods to improve its dispersion and mechanical properties. The effects of different types of interfaces, formed by four surface modifications, namely KH550, KH570, stearic acid, and titanate, on the flame retardancy of composite systems have been investigated in the present study. The results showed that the four surface modifiers formed chemical bonds with the surface of magnesium hydroxide, which promoted the dispersion of particles in the matrix. However, due to the different effects of the various surface modifiers and polymer molecular chains, the interfaces exhibited different chemical structures and physical strengths, which affected the combustion of the composite materials into carbon. Thus, the composites demonstrated different flame‐retardant properties. The surface modifiers KH550, KH570 and titanate can form chemical bonds with the ethylene‐vinyl acetate (EVA) copolymer and have, thereby, a strong effect on the interfaces, which resulted in a slow ignition of the materials and the formation of a graphite carbon structure that is advantageous for heat transfer and oxygen insulation. This is conducive to the flame‐retardant performance of the composite systems. [ABSTRACT FROM AUTHOR]

To enhance the flame‐retardant characteristics of ceramifiable polyethylene (PE) composites, a composite flame retardant comprising ammonium polyphosphate (APP) and melamine cyanurate (MCA) was integrated. This addition markedly bolstered their flame‐retardant attributes. A meticulous exploration was conducted to ascertain the impacts of APP and MCA on the ceramifiable PE composites' visible morphology, mechanical robustness, and dimensional constancy, and to study the phase transition and microstructure deformation during sintering. Findings underscored that the amalgamation of APP/MCA markedly enhanced the flame resistance of these ceramifiable composites, registering a limiting oxygen index of 25.6% and achieving the vertical burning test (UL‐94) rating of V‐0. The collaborative flame‐retardant action of APP/MCA significantly enhanced the flame resistance of the PE composites while effectively mitigating the composite's propensity to drip. Upon detailed phase analysis, a eutectic reaction was observed between APP and wollastonite fiber, culminating in the genesis of a novel crystalline phase, calcium pyrophosphate (Ca2P2O7). When subjected to elevated temperatures, glass–ceramics manifest with both crystalline and vitreous phases. The proportion of the vitreous phase plays a pivotal role in influencing the ceramic's overall performance. [ABSTRACT FROM AUTHOR]

Epoxy resins (EPs) are highly flammable, and traditional flame retardant modifications often lead to a significant reduction in their mechanical performance, limiting their applications in aerospace and electrical and electronic fields. In this study, a novel flame retardant, bis(4-(((diphenylphosphoryl)oxy)methyl)phenyl)phenyl phosphate (DMP), was successfully prepared and introduced into the EP matrix. When the addition of DMP was 9 wt%, the EP/9 wt% DMP thermosets passed the UL-94 V-0 rating, and their LOI was increased from 24.5% of EP to 35.0%. With the introduction of DMP, the phosphoric acid compounds from the decomposition of DMP promoted the dehydration and charring of the EP matrix, and the compact, dense char layer effectively exerted the shielding effect in the condensed phase. Meanwhile, the produced phosphorus-containing radicals played a quenching effect in the gas phase. As a result, the peak heat release rate (PHRR) and total heat release (THR) of EP/9 wt% DMP were reduced by 68.9% and 18.1% compared to pure EP. In addition, the polyaromatic structure of DMP had good compatibility with the EP matrix, and the tensile strength, flexural strength and impact strength of EP/9 wt% DMP were enhanced by 116.38%, 17.84% and 59.11% in comparison with that of pure EP. This study is valuable for expanding the application of flame-retardant EP/DMP thermosets in emerging fields. [ABSTRACT FROM AUTHOR]

Wood modification has been explored in various ways to enhance dimensional stability and reduce flammability, with a focus on environmentally friendly treatments to meet market demands. This study aimed to investigate the efficacy of new, potential fire-retardant materials. Specifically, the study examined the combination of tripotassium citrate (TPC), a water-soluble and bio-based fire retardant, with sorbitol and citric acid (SorCA), an eco-friendly thermosetting resin previously studied. While TPC is known to control combustion, its application in wood modification has not been thoroughly researched. To assess the fixation and flammability of these fire retardants, tests were conducted on Scots Pine (Pinus sylvestris L.), including chemical analysis, dimensional stability, mechanical properties, flame retardancy, and leaching tests. The combination of SorCA and TPC showed high weight percent gain (WPG) values; however, leaching and anti-swelling efficiency (ASE) tests revealed challenges in fixation stability. The dynamic mechanical properties were reduced, whereas the static strength values were in the same range compared with untreated wood. While TPC exhibited high flame retardancy prior to leaching, its efficacy diminished post-leaching, underscoring challenges in fixation and the need for improved retention strategies. Bunsen burner tests conducted on leached specimens indicated enhanced performance even under severe leaching conditions as per the EN 84:2020 procedure. However, cone calorimetry measurements showed less favorable outcomes, emphasizing the necessity for further investigation into optimizing TPC retention and enhancing treatment efficacy. [ABSTRACT FROM AUTHOR]

Currently, postulated trends and law regulations tend to direct polymer technology toward sustainability and environmentally friendly solutions. These approaches are expressed by keeping materials in a loop aimed at the circular economy and by reducing the environmental burdens related to the production and use of polymers and polymer-based materials. The application of recycled or waste-based materials often deals efficiently with the first issue but at the expense of the final products' performance, which requires various additives, often synthetic and petroleum-based, with limited sustainability. Therefore, a significant portion of research is often required to address the drawbacks induced by the application of secondary raw materials. Herein, the presented study aimed to investigate the fire performance of polymer composites containing highly flammable matrix polyurethane (PU) foam and filler ground tire rubber (GTR) originating from car tire recycling. Due to the nature of both phases and potential applications in the construction and building or automotive sectors, the flammability of these composites should be reduced. Nevertheless, this issue has hardly been analyzed in literature and dominantly in our previous works. Herein, the presented work provided the next step and investigated the input of nanoclays to the synergistic flammability reduction in flexible, foamed PU/GTR composites. Hybrid compositions of organophosphorus FRs with expandable graphite (EG) in varying proportions and with the addition of surface-modified nanoclays were examined. Changes in the parameters obtained during cone calorimeter tests were determined, discussed, and evaluated with the fire performance index and flame retardancy index, two parameters whose goal is to quantify the overall fire performance of polymer-based materials. [ABSTRACT FROM AUTHOR]

Over traditional flame retardants, the hybrid material technology of flame retardant combines separate constituents into an entirety, demonstrating the benefit of the simultaneous development in polymer flame retardant. Zinc-layered hydroxide, borate, and thermoplastic polyurethane were used to create LZH/B/TU, a new organic-inorganic composite flame retardant. The structure of LZH, LZH/B, and LZH/B/TU was studied after synthesis with analysis spectroscopy. The borate ion was effectively intercalated into the interlayer space of the LZH, according to the XRD and FTIR studies. Using EDS analysis, the chemical makeup of the materials was assessed. The morphology of the synthesized product was identified using FESEM. The dynamic mechanical thermal (DMT) properties of the optimum sample were evaluated with DMTA analysis. The fire risk of epoxy resin was considerably reduced by using a small amount of LZH/B/TU. According to the flammability test and plate temperature experiment, LZH/B/TU with 1% w/w led to the creation of the char layer's capacity to insulate heat with strong thermal resistance, resulting in dramatically reduced fire hazards. [ABSTRACT FROM AUTHOR]

The utilization of natural fibers obtained from leather industrial wastes contributes to a circular economy and aids to the reduction in the usually high loadings of mineral flame-retardant additives employed to impart the flame retardancy in polymer systems. The present work investigates the relationship between viscoelastic properties and flame retardancy of thermoplastic starch multicomponent systems loaded with leather waste, aluminum trihydroxide used as flame-retardant additive, and bentonite clay. Different blending temperatures and rotational speeds during extrusion process are tested for the multicomponent systems. Rheological, morphological, flammability, thermal analysis, and tensile mechanical test are also used to characterize the obtained multicomponent systems. A detailed investigation of the viscoelastic properties through Han, Cole–Cole, and van Gurp–Palmen diagrams indicated that the fibers have to be well dispersed in the polymer matrix forming a network structure and that the material has to exhibit viscoelasticity to a moderate level, i.e., not too viscous and not too elastic as observed in the VGP diagram in order to impart the flame retardancy effect in the multicomponent system. These multicomponent systems with enhanced properties are a promising and sustainable alternative to traditional high-loaded flame-retardant systems taking advantage of the landfill disposal in local areas where leather wastes are a problem the great attention contributing to a circular economy. [ABSTRACT FROM AUTHOR]

This study aims to create fire-resistant performance of polyurethane (PU)-coated textiles by adding wool powder as a flame retardant on both cotton and polyester fabrics. A flame-retardant surface was therefore developed by coating the fabrics with a mixture of PU and wool powder and characterised by using Fourier transform infrared spectroscopy and scanning electron microscopy. The experimental results demonstrated that with a coating thickness of 0.5 mm onwards, an improvement in the fire-resistant properties is observed. Unlike fabrics coated only with PU, the addition of wool powder allows the fabrics to resist the flame at 5 and 10 s. Water and air permeability properties of the coated fabrics were also evaluated and show interesting and complementary results. Integration of wool powder as a flame retardant is a promising approach to develop fire-resistant fabrics that can lead to wide applications in fire protection and safety. [ABSTRACT FROM AUTHOR]

To address the increasing demand for sustainable biomaterials because of the excessive usage of fossil fuel and growing concerns with the environment, a novel biodegradable and environmentally friendly rigid polyurethane foam (RPUF) has been synthesized. These foams are derived from chemically modified soybean oil-based polyol (SBO-polyol) obtained through the formation of oxirane followed by the opening of the oxirane reaction. Polyurethane foam is generally used in construction, furniture, and automobile industries but is highly flammable and releases toxic fumes in combustion. In this study, an efficient synergistic effect of non-halogen flame-retardant (FR) melamine salt, 2-carboxyethyl(phenyl)phosphinic acid melamine salt (CMA) was synthesized from 2-carboxyethyl(phenyl)phosphinic acid (CEPP) and melamine (MA). Fourier transform infrared (FT-IR) spectroscopy characterized the chemical structure of CMA. Three different FRs, MA, melamine cyanurate (MC), and CMA were separately introduced in increasing quantities for the foam preparation to suppress the flame during combustion. The influence of these FRs on the thermal properties, flame retardancy, morphology, physical, and mechanical properties of the prepared RPUFs was studied through closed cell content, apparent density, compression test, horizontal burning test, thermogravimetric analysis (TGA), and gel permeation chromatography (GPC), scanning electron microscopy (SEM). The addition of 28.56 wt% of MA (MA-15), MC (MC-15), and CMA (CMA-15) presented a burning time of 10.1 s with weight loss of 5.34% and 28.4 s with 13.02% and 15.25 s with 8%, respectively. The findings demonstrated that all three FRs gave RPUF good FR properties. [ABSTRACT FROM AUTHOR]

Optimizing composite materials is crucial for engineering advancements because it allows for the creation of materials tailored to specific functional requirements, thereby enhancing efficiency, safety, and sustainability. This study examines both the combined and individual effects of long flax fiber (LFF) bundles, short basalt fibers (BF), and rice husk powder (RHP) on the properties of polypropylene (PP) hybrid composites. LFF primarily provides mechanical strength, BF enhances mechanical, thermal, and flame‐retardant properties by filling gaps, and RHP reinforces and improves the overall composite. Contrary to previous studies that relied on random combinations, this research employs a systematic Box–Behnken design (BBD) for three variables: LFF plies, BF, and RHP by weight percentage. This approach facilitated the development of a new second‐order regression equation via response surface methodology (RSM), clarifying the contribution of each component, with R2 values exceeding 0.85, indicating high predictability. Optimization, conducted using a non‐dominated sorting genetic algorithm (NSGA‐II), demonstrated that the optimal composites significantly outperformed the non‐optimized ones in mechanical strength, thermal stability, and flame retardancy. Compared to the average values before optimization, improvements post‐optimization included increases of 49.86% in tensile strength (TS), 38.82% in TS modulus, 73.93% in char yield (YC), and 29.81% in peak heat release rate (pHRR). Specifically, the fire performance index improved by 237.5% and the fire growth index by 101.33%, compared to pure PP, highlighting significant advancements in fire safety. This study shows that mathematical equations can predict composite properties, helping to select balanced compositions without sacrificing flammability. Highlights: Multi‐filler approach technique used for manufacturing of PP composites.LFF, BF & RHP optimize mechanics & flammability.Box–Behnken design predicts optimal composition for superior properties.NSGA‐II optimization improves tensile, thermal & flame retardant properties. [ABSTRACT FROM AUTHOR]

This study endeavors to enhance the safety of lithium‐ion batteries (LIBs) by synthesizing a polyamide acid (PAA)/Al2O3 composite spinning solution using 4,4′‐diaminodiphenyl ether (ODA) and pyromellitic anhydride (PMDA) as monomers, and nano‐Al2O3 as a thermal conductivity filler. Subsequently, the PAA/Al2O3 fiber membrane is fabricated via electrostatic spinning, followed by gradient heating imidization to produce a polyimide (PI)/Al2O3 composite membrane. This membrane is then dipped into a boron nitride (BM) slurry to ultimately yield an organic–inorganic PI/Al2O3/BM composite separator with superior flame‐retardant and thermal conductivity properties. The thermal stability, flame retardancy, electrolyte wettability, mechanical integrity, and cycle rate performance of the composite membranes are rigorously evaluated. The results demonstrate that the PI/5% Al2O3/BM composite membrane exhibits the most favorable overall performance, with no shrinkage observed at 200°C and no significant changes after sustained ignition for 10 s. The incorporation of the thermal conductivity Al2O3 filler significantly enhances the heat transfer properties of the composite separator. The room temperature ionic conductivity reaches 2.786 mS cm−1 after electrolyte absorption, and the initial discharge capacity of the assembled battery is 156.28 mAhg−1. Following 100 charge/discharge cycles at 0.2C, the capacity retention rate is 97.7%, and at a discharge rate of 5C, the capacity retention rate is 74.9%. [ABSTRACT FROM AUTHOR]

Replacing antimony trioxide (Sb2O3) with an environmentally friendly alternative is of great scientific and commercial value for studying the flame retardant properties of flexible PVC (fPVC) films in automotive interior materials. This study develops flame retardant fPVC films with reduced Sb2O3 content by introducing stannic oxide (SnO2) and zinc borate (ZB). The results indicate that the fPVC film with ZB partially replacing Sb2O3 exhibits superior flame retardancy and smoke suppression compared to the product containing SnO2. The peak heat release rate (PHRR), total heat release (THR), and total smoke release (TSR) of 2ZB/2Sb2O3 fPVC film are reduced by 32.1%, 27.5%, and 22.1%, respectively, compared to that of 4Sb2O3 contained fPVC film. The increase in flame retardancy is attributed to the presence of ZB, which compensates for the deficiency of char formation ability of Sb2O3 in the condensed phase. The PHRR and THR of 2SnO2/2Sb2O3 fPVC film decrease by 27% and 12.5%, respectively, compared to that of 4Sb2O3 fPVC film, while the TSR increases by 16.5%. This study develops a straightforward approach to creating a flame retardant fPVC film that is suitable for the latest industrial application in automotive interior materials. [ABSTRACT FROM AUTHOR]

The development of green and efficient bio‐based flame retardants is very important for the development of flame‐retardant cellulosic paper. In this study, a novel type of starch‐based synergistic flame retardant (SAPU) was prepared using corn starch as carbon sources, amino trimethylphosphonic acid, and urea as phosphorus and nitrogen sources through the one‐pot method. Subsequently, the flame‐retardant cellulosic paper was prepared by impregnation, and the flame retardancy of the cellulosic paper was evaluated by vertical combustion, limiting oxygen index (LOI), and thermogravimetric analysis. The results demonstrated that the SAPU exhibited a favorable flame‐retardant effect on cellulosic paper. At a concentration of 25.0%, the vertical burning residue of flame‐retardant paper accounted for 49.16% of the total length of the paper sample, while the LOI was 39.4%. The tensile strength and burst index of cellulosic paper were found to be decreased by 6.36% and 19.1%, respectively, in comparison to the base paper. Conversely, the ring crush strength was observed to be increased by 156.2%. The carbon residue rate at 700°C under a nitrogen atmosphere rose from 11.56% of the base paper to 28.77% of the flame‐retardant paper. The flame‐retardant SAPU effectively improved the thermal stability of cellulosic paper. [ABSTRACT FROM AUTHOR]

Carbon fiber (CF)‐reinforced epoxy resin (EP) composites are lightweight materials with excellent comprehensive performance. However, the flammability of EP and the poor interfacial bonding between CF and EP are two key disadvantages that limit their further applications. Here, a kind of water‐soluble lignin‐based CF sizing agent (ELBEDK) is prepared through hydrophilic modification of enzymatic lignin, which can significantly enhance the interfacial interaction between CF and EP. Additionally, a highly efficient intumescent flame retardant (LMA) is prepared. The EP, enzymatic lignin, LMA and CF sized ELBEDK are compounded to obtain the fire‐safety CF reinforced composites (SCF/FEP/L). The flame retardancy of SCF/FEP/L with 7% LMA (SCF/FEP7) reached V‐0 rating. Moreover, SCF/FEP/L with 7% LMA and 15% lignin (SCF/FEP7/L15) present an limiting oxygen index (LOI)of 30.2% and V‐0 of UL‐94. Specifically, the total smoke production and the heat release rate are 47.8% and 46.81% lower than that of SCF/EP, respectively, indicating the improved smoke suppression and flame retardancy. The IFSS and flexural strength of SCF/FEP7/L15 are improved to be 59.4 MPa and 511.1 MPa, respectively. This study presents a simple approach to fabricate low‐cost high performance lignin‐based flame retardant CF/EP biocomposites with wide application potential. [ABSTRACT FROM AUTHOR]

In this study, a 4‐(hydroxymethyl)‐2,6,7‐trioxa‐1‐phosphabicyclo[2.2.2]octane 1‐oxide (PEPA)‐functionalized acrylate monomer, PEPAA, is designed and utilized for the synthesis of macromolecular flame retardants poly(PEPAA‐co‐AM) with varying PEPAA/AM ratio through copolymerization with acrylamide (AM). The poly(PEPAA‐co‐AM) is then incorporated into polypropylene (PP) to prepare PP/poly(PEPAA‐co‐AM) composites. The flame retardant effect of poly(PEPAA‐co‐AM) on PP is investigated using cone calorimetric test (CCT), and compared with that of PEPAA homopolymer (P‐PEPAA), AM homopolymer (PAM), and blends of P‐PEPAA/PAM. The results demonstrate that, in comparison with P‐PEPAA, PAM, and blends of P‐PEPAA/PAM, the incorporation of poly(PEPAA‐co‐AM) significantly enhances the flame retardancy of PP. Notably, the best flame retardancy is achieved when the ratio of PEPAA/AM copolymerization in poly(PEPAA‐co‐AM) is 2/8. The morphology and composition of residual chars from combustion are analyzed using SEM‐EDS while the residual graphitization degree is examined through Raman spectroscopy. Additionally, TG‐FTIR‐MS is utilized to investigate the pyrolysis products in gas phase during thermal decomposition of poly(PEPAA‐co‐AM). Based on these experimental results, a flame retardant mechanism for poly(PEPAA‐co‐AM) is proposed. The PP/poly(PEPAA‐co‐AM) composites not only retain the excellent processing properties of pure PP but also exhibit enhanced mechanical properties. [ABSTRACT FROM AUTHOR]

[Display omitted] The construction of supramolecular aerogels still faces great challenges. Herein, we present a novel bio-based supramolecular aerogel derived from G-Quadruplex self-assembly of guanosine (G), boric acid (B) and sodium alginate (SA) and the obtained GBS aerogels exhibit superior flame-retardant and thermal insulating properties. The entire process involves environmentally friendly aqueous solvents and freeze-drying. Benefiting from the supramolecular self-assembly and interpenetrating dual network structures, GBS aerogels exhibit unique structures and sufficient self-supporting capabilities. The resulting GBS aerogels exhibit overall low densities (36.5–52.4 mg/cm3), and high porosities (>95 %). Moreover, GBS aerogels also illustrate excellent flame retardant and thermal insulating properties. With an oxygen index of 47.0–51.1 %, it can easily achieve a V-0 rating and low heat, smoke release during combustion. This work demonstrates the preparation of intrinsic flame-retardant aerogels derived from supramolecular self-assembly and dual cross-linking strategies, and is expected to provide an idea for the realization and application of novel supramolecular aerogel materials. [ABSTRACT FROM AUTHOR]

[Display omitted] Enhancing the flame retardancy of epoxy (EP) resins typically entailed a trade-off with other physical properties. Herein, hyperbranched poly(amidoamine) (HPAA) and phytic acid (PA) were used to functionalize graphene oxide (GO) via electrostatic self-assembly in water to prepare a phosphorus-nitrogen functionalized graphene oxide nanosheet (PN-GOs), which could be utilized as high efficient flame-retardant additive of epoxy resin without sacrificing other properties. The PN-GOs demonstrated improved dispersion and compatibility within the EP matrix, which resulted in significant concurrent enhancements in both the mechanical performance and flame-retardant properties of the PN-GOs/EP nanocomposites over virgin EP. Notably, the incorporation of just 1.0 wt% PN-GOs yielded a 20.4, 6.4 and 42.7 % increases in flexural strength, flexural modulus and impact strength for the PN-GOs/EP nanocomposites, respectively. Furthermore, simultaneous reductions were achieved in the peak heat release rate (pHRR) by 60.0 %, total smoke production (TSP) by 43.0 %, peak CO production rate (pCOP) by 57.9 %, and peak CO 2 production rate (pCO 2 P) by 63.9 %. This study presented a facile method for the design of GO-based nano flame retardants, expanding their application potential in polymer-matrix composites. [ABSTRACT FROM AUTHOR]

To address the flammability concerns of silicone acrylate emulsion (SAE), it is of utmost importance to develop composite coatings that excel in flame retardancy and smoke suppression. In this research, we have utilized carboxymethyl chitosan (CMCS) bonded‐melamine polyphosphate (MPP)/sodium lignosulfonate (LS) to create SAE composite SiPC coatings through the sol–gel method for flame‐retarding plywood. The results obtained that CMCS pretreatment of MPP (CMPP) facilitates the filling of P‐containing components in the SAE composite SiPC coating to further form a continuous and dense cross‐linked structure. Appropriate dosage of LS (2 wt.%) improve the flame retardancy of the coatings, which is manifested the peak heat release rate drops from 237.4 to 142.4 kW m−2, total smoke production (TSP) is also significantly reduces by 55%. Notably, the coating undergoes a transformation into a nonflammable vitreous polyphosphate barrier layer while burning, effectively preventing the transfer of heat or mass. According to the calculation results of adsorption kinetics, the formaldehyde adsorption rate of the SiPC coating increased by 76.6%. Furthermore, the pyrolysis kinetics identify that the 3D Z.‐L.‐T model governs the coatings' pyrolysis, and the appropriate LS makes the pyrolysis Eα rise from 300.98 to 326.50 kJ mol−1 at 358 – 439°C, indicating enhanced thermal stability. In conclusion, our research has introduced a novel design strategy for developing the SiPC coating with exceptional properties, studies the flame‐retardant mechanisms of SAE composite SiPC coating, promotes the advancement of sustainable urban building materials, and explores a green, clean, and low‐cost ecological technology approach. [ABSTRACT FROM AUTHOR]

Although numerous investigations study the improvement of flame retardancy of epoxy resins using additives, maintaining the flame retardant (FRs) modes of action present in the resins upon transfer to composites is challenging. In this study, ammonium polyphosphate (APP) and inorganic silicate (InSi) are loaded at 10%, 30%, and 50% by weight, in a diglycidyl ether of bisphenol A (DGEBA) resin cured with dicyandiamide and transferred to bidirectional (BD) glass fiber (GF) composites. Although a 50% loading of the FRs impacts the curing kinetics of the resin system, the effect on the glass transition temperature of the resin system remains negligible compared to reactive FRs in the state of the art integrated into the resin's chemical structure. Increasing the FR content improved the heat release characteristics in both the resins and composites. However, the charring mode of action is completely suppressed in the formulation with 10% APP + InSi. A 30% concentration of the FRs restored the charring action in the composite and the GFs provide increased protective layer action upon transfer to the composites. This study highlights the importance of accounting for the changing dynamics related to processing and flame retardancy upon transferring FRs from resins to composites. [ABSTRACT FROM AUTHOR]

Phosphorus-containing flame retardants have attracted attention due to their outstanding flame retardancy, enhanced thermal stability, and limited toxic smoke emission. Bio-based phosphorus-containing flame retardants could be excellent options to impart environmental benefits, renewability, and sustainability to these materials. Lignin is an underutilized but abundant and sustainable material that can be used to serve this purpose. In the present work, a lignin-derived flame retardant was produced following the facile solvent-free polycondensation reaction of kraft lignin (KL) and phytic acid (PHA) at a low temperature in an aqueous system. The optimized conditions for this reaction were 1/0.4 mol/mol KL/PHA, pH 11, 20 °C, and 20 min. By utilizing advanced NMR (H, P, and HSQC), XPS, and FTIR techniques, the covalent bonding of the phosphorus of PHA with the oxygen of aliphatic and aromatic hydroxyl groups of KL was confirmed. C–P–O and P–O–P bonds provided high decomposition temperature (Tmax), high glass transition temperature (Tg), and char formation in the product. The presence of phosphorus atoms was observed on the combusted material by EDS mapping and EDX, illustrating the increase in the intensity of this element after combustion at 800 °C. The results of this work provided a new approach for preparing a fully bio-based flame-retardant with limited smoke density (i.e., a decrease from 34% for KL to 17.7% for modified KL) and a higher limiting oxygen index (i.e., an increase from 21.8% for KL to 26% for modified KL) following a green chemistry concept. [ABSTRACT FROM AUTHOR]

Polyimide aerogels are often constrained by the poor mechanical performance when used as thermal insulation. In addition, there is requirement for flame retardant performance in the practical use. In this paper, a fiber‐reinforced polyimide aerogel material was prepared by compounding polyisophthaloyl metaphenylene diamine fibers with the aerogel, which present good thermal insulation and excellent mechanical properties, flame retardancy, thermal stability, and certain hydrophobicity, as well as being very lightweight. The compressive strength of the polyimide aerogel was increased from 0.34 to 0.58 MPa by using the fibers as the reinforcing phase; meanwhile, the flame‐retardant property was improved, and the limit oxygen index was increased from 33.8 to 36.5. The composite aerogel material has good potential for application in the fields of thermal insulation, building insulation, aerospace, etc. [ABSTRACT FROM AUTHOR]

Cyclic olefin copolymer (COC) is recognized as a prospective material for thermal insulation foam in the construction industry. Nonetheless, enhancing its flame retardancy is problematic due to the carbon and hydrogen elements present in its macromolecular chains. In this study, we introduce a boric acid-modified zeolite socony mobil No. 5 (BZ5) as a synergist to develop an intumescent flame retardant (IFR) COC composite. We employed scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), the limiting oxygen index (LOI), cone calorimetry testing (CCT), and fourier-transform infrared spectroscopy (FTIR) to investigate the composite's surface morphology, distribution of flame retardants, and the characteristics of the carbon residue's structure and morphology. The incorporation of BZ5 as a synergist significantly improved the LOI value to a maximum of 28.5%, surpassing the 15.3% observed in the unmodified COC. Additionally, the char residue content increased from 0.97% to 19.7% with BZ5 in the COC composite. SEM and FTIR analyses revealed a denser microscopic carbon residue structure post-boron modification. Our findings indicate that an appropriate content of boric acid modification effectively enhances the flame retardancy of COC. [ABSTRACT FROM AUTHOR]

Polylactic acid (PLA) is a widely used biodegradable material, but its inadequate fire protection properties have the quest for developing environmentally friendly, effective, and multifunctional flame retardants to enhance PLA's flame retardancy. Here, designed and synthesized bio-based double-shell nickel–cobalt-based flame retardant (NiCo-BH@BPA@CS) as a green flame retardant through layer-by-layer assembly using NiCo-based bimetallic hydroxide (NiCo-BH), benzenephosphonic acid (BPA) and chitosan (CS). Subsequently, this multifunctional flame retardant (NiCo-BH@BPA@CS) was melted into the PLA matrix as flame retardant additions to prepare PLA/NiCo-BH@BPA@CS composites. Benefiting from the organic modification, NiCo-BH@BPA@CS presented excellent dispersion in the PLA matrix. The incorporation of NiCo-BH@BPA@CS simultaneously enhanced the fire safety, thermal stability and charring capability of the PLA composites. With the addition of 20 wt% NiCo-BH@BPA@CS, the LOI value of NiCo-BH@BPA@CS composite reached 32.5% and passed the UL-94 V-0 class. After cone calorimetric testing, it was found that the PHRR, THR and FGI values of PLA/NiCo-BH@BPA@CS composites were reduced by 19.9%, 23.9% and 22.4%, respectively, compared to PLA/NiCo-BH. More importantly, the residual char of PLA/NiCo-BH@BPA@CS exhibited a significantly reduced presence of large cracks compared to that of PLA/NiCo-BH and indicated a more densely formed residual char. This was mainly attributed to the synergistic effect of transition metal nickel cobalt, P in benzenephosphonic acid and N in chitosan, which can promote the compactness of char layers with fine microstructure formed in the decomposition process of PLA/NiCo-BH@BPA@CS composites. This work provides an environment-friendly layer-by-layer assembly modification strategy for enhancing the dispersion of and flame retardant efficiency of NiCo-based flame retardant which opens a door for broad applications of PLA. [ABSTRACT FROM AUTHOR]

Hydrophilic mesoporous silica aerogel particles were synthesized via self-assembly of amphiphilic polymer (Ph8-PEG6-PEOS) and its instantaneous hydrolysis and condensation in the alkaline environment. Meanwhile, the capture and encapsulation of flame retardant (IPPP) and oil soluble dyes were successively completed during the two processes above. Observed by thermal field scanning electron microscopy (TFESEM), the average diameter of aerogel particles reached about 10 µm. BET surface area analysis displayed that the existence of oil-phase component (IPPP) can result in the expansion of pore diameter, and promote the evolution of mesopores into macropores. Then, IPPP@SiO2 aerogel particles were utilized to improve the flame retardancy of polyvinyl alcohol (PVA) coatings implemented onto cotton yarns, by employing developed knife coating procedure in an aqueous suspension. The thermal stabilities and flammability behaviors of the samples were evaluated by thermogravimetric analysis (TGA), limiting oxygen index (LOI), and vertical burning test, respectively. Both thermal decomposition temperature and LOI value of coating composites gradually increased with the increment of IPPP@SiO2-n (n = 10, 30, 50, 70), attaching to the synchronous advancement in stretching property. Furthermore, coatings were thickened by degrees from 0.4 to 4 mm, based on knife coating in multi-stage layer-by-layer mode, to build an ordered porous structure with the assisted adhesion of PVA. The following sintering preserved the close packing of silica aerogel particles and facilitated the formation of a coherent porous monolithic material with excellent thermal insulation performance. [ABSTRACT FROM AUTHOR]

[Display omitted] Moist-electric generators (MEGs), which are capable of spontaneously generating energy from ubiquitous moisture, are considered as a potential power supply candidate for wearable electronics. However, the application of the MEGs in the wearable field is still challenging due to the low electric output and the lack of wearable attributes such as breathability and flame retardancy. Herein, we demonstrated a wearable MEG with high power-output, breathability and flame retardancy, which was fabricated by designing an asymmetrical nanofiber assembly using hydrophilic polyvinyl alcohol/phytic acid (PVA/PA) and hydrophobic polyvinylidene difluoride (PVDF) nanofiber membranes. Owing to the synergistic effects of strong water absorption, enhanced ion release and numerous micro-nano transport channels, a single MEG of 1 cm2 could constantly generate high direct-current (DC) power, i.e., a voltage of 1.0 V, a current of 15.5 μA, and a power density of 3.0 μW cm−2, outperforming other reported nanofiber-based MEGs. More importantly, the asymmetric nanofiber structure ensured the moisture circulation inside MEG and thus produced a sustained voltage output for 7 days without any deterioration. The MEG also showed good flexibility, air/moisture permeability and flame retardancy, which give it necessary wearable attributes. Furthermore, large-scale integration of MEG units could be readily realized to fabricate a power source device for driving different portable electronics, while the moisture sensitivity made the MEG well used for sensing applications (e.g., respiration monitoring, fire warning). [ABSTRACT FROM AUTHOR]

Compared with other types of sensors, capacitive flexible pressure sensors (CFPS), with low sensitivity, are more susceptible to environmental changes. It is still a considerable challenge to achieve high sensitivity, excellent mechanical properties and long-time structural stability simultaneously. Targeting the aforementioned issues, herein, Ti3C2 (MXene) with high dielectric constant was firstly chemically modified with a poly(ionic liquid) (PIL) via surface-initiated ATRP, and then combined with a porous polyurethane foam (PUF) 3D network structure via a one-step blending foaming method. Thanks to the organic-inorganic hybrid network based on the PU/MXene porous structures and the uniformly distributed micro-capacitor structure provided by MXene@PIL, the mechanical properties, structural stability, flame retardancy and dielectric properties of the composite foam were all significantly enhanced. When the content of MXene@PIL was 10%, the sensitivity of CFPS based on this dielectric were 17.1, 5.2, and 2.5/KPa in the pressure ranges of 0-1 KPa, 1-12 KPa and 12-100 KPa, respectively. In addition, the sensor showed the response and recovery times of 88 and 82 ms under a low pressure of 355 Pa. The light, flexible sensor prepared in this work is expected to be used in wearable devices to monitor physiological signals, and it should also be a good candidate for the next generation of man-machine interface characterization devices. [ABSTRACT FROM AUTHOR]

The properties and structure of flexible PVC by incorporating zinc borate (ZB)‐modified diantimony trioxide (Sb2O3) were investigated. The results of flame retardancy and smoke suppression testing indicate that there was an obvious maximum Limited oxygen index (LOI) value of PVC/20 wt.% ZB–Sb2O3 composites reached 37.5% and passed the UL 94 V‐0 rating. An obvious synergistic effect between ZB and Sb2O3 was observed by LOI, SDR, and TG. Moreover, remarkable decreases in the smoke density were observed when ZB–Sb2O3 was incorporated into PVC. In addition, the tensile strength and elongation at break of PVC/ZB–Sb2O3 composites was higher than PVC/Sb2O3 composites, and this ameliorative effect was mainly arising from the ZB–Sb2O3 nanoparticles, which reduced the degree of fatal defects on PVC. The addition of ZB and Sb2O3 greatly increased the amount of residual char and apparently improved the mechanical properties of PVC composites. According to scanning electron microscopy photographs of residual char, after thermal decomposition, there were many fragments linked to the condensed phase and the compact char layer. Fourier transform infrared spectroscopy shows the residues char was composed of benzene ring, the flame retardants occurred and the condensed phase with significant interactions. [ABSTRACT FROM AUTHOR]

The envelope structure with high light transmittance accounts for an increasing proportion of building energy consumption, which is one of the shortcomings of energy conservation and emission reduction. Cellulose-based aerogel has become a research topic of interest because of its low thermal conductivity and good mechanical properties. However, most cellulose-based aerogels are opaque and flammable limiting their applications. Herein, cellulose/silica composite aerogels (CAS) with "organic–inorganic" structures were fabricated by two-step sol–gel method, spin-coating technique and supercritical CO2 drying, using the ionic liquid 1-allyl 3-methylimidazolium chloride salt to dissolve the Cotton pulp, followed by the addition of tetraethylorthosilicate (TEOS) and methyltriethoxysilane (MTES) co-precursors into the cellulose gels. The synthesis mechanism, microstructure, mechanical and thermal properties of as-prepared aerogels samples were investigated. The obtained CAS have low density (0.093–0.170 g/cm3), high specific surface area (660.87–1089.70 m2/g), and high mechanical property (compressive strength of 18.74 MPa, tensile strength as high as 1.54 MPa, and bending tests above 500 times). In particular, the CAS4 shows the lowest thermal conductivity (0.0188 W·m−1·K−1), good thermal stability (> 331 °C), high transparency (91.7%) and excellent flame retardancy. In addition, the self-designed aerogels glasses model was placed in a real outdoor environment for 5 h. The results showed that the temperature difference between the inside and outside of the aerogels glasses model was as high as 12 ℃ under the thermal equilibrium state. Thus, the as-prepared high-performance cellulose/silica composite aerogels may increase the role of aerogels glasses in the building envelope and have promising applications in transparent energy-efficient construction and thermal insulation. [ABSTRACT FROM AUTHOR]

Research on functional cotton fabrics has been focused on flame retardancy and antibacterial propertie to address the hazard of fire and harmful microorganisms. However, flame retardant and antibacterial treatments face the problems of cumbersome processes and unsatisfactory performance due to compatibility issues between additives and the nondurability of functional cotton fabrics. Herein, we prepared multifunctional cotton fabrics (DAM-CF-Cl) based on surface graft copolymerization of three vinyl monomers, namely diethyl methacryloyl phosphoramidate, 3-allyl-5, 5-dimethylhydantoin (ADMH, N-halamine precursor monomer) and N, N'-methylenebisacrylamide, which exhibited notably enhanced flame retardant, smoke suppression and antibacterial properties compared to the widely adopted complex methods. Compared to control cotton fabrics, the limiting oxygen index of DAM-CF-Cl containing fabrics improved from 18 to 27.6%, and the heat and smoke production of DAM-CF-Cl equipped samples exhibited a conspicuously decreasing tendency in cone calorimetry tests. In addition, due to the introduction of the N-halamine structure of ADMH, the efficient and rapid antibacterial properties of DAM-CF-Cl were confirmed. This work provides a new insight into a convenient method for comprehensive multifunctional treatment of textiles. [ABSTRACT FROM AUTHOR]

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A phosphorus-nitrogen organic salt flame retardant (EP) was synthesized through a simple one-step reaction using etdronic acid as a phosphorus source (EA) and antiphenylenediamine (PPD) as a nitrogen source. Its structure was characterized by !H-NMR and FTIR spectroscopy. The flame-retardant TPU was prepared by mixing TPU with EP using a melt blending method, and its thermal stability, flame retardant performance, and mechanical properties were investigated. The results indicated that the addition of EP generated little effect on the thermal stability of TPU, and its flame retardancy was significantly improved. The flame-retardant TPU containing 3 wt. % EP (TPU-3% EP) obtained a limiting oxygen index of 28. 40 vol. % and also achieved a UL 94 V"0 classification in the vertical burn experiment. The residual carbon yield (CY) was more than twice that of pure TPU. Compared with pure TPU, the total heat release and peak heat release rate of TPU-3% EP were reduced by 22. 12% and 61. 85%, respectively, and its effective combustion heat was also reduced. EP can enhance the flame-retardant performance of TPU mainly by catalyzing the condensation phase to form charcoal and isolate thermal oxygen exchange. Moreover, the free radical quenching effectiveness in the gas phase also generates a certain flame-retardant effect. [ABSTRACT FROM AUTHOR]

A phosphorus-containing compound, (oxybis(4,1-phenylene))bis(phenylphosphine oxide) (ODDPO), was successfully synthesized and used as a flame retardant for epoxy resin (EP). The results demonstrated that EP/ODDPO, containing 1.2 wt% phosphorus, achieved a vertical burning V-0 rating, with a limited oxygen index value of 29.2%, indicating excellent flame retardancy. Comprehensive evaluations revealed that ODDPO exhibited both gas-phase and condensed-phase flame-retardant effects on EP, with a particularly notable barrier effect. In addition, the incorporation of ODDPO had a minimal negative impact on the glass transition temperature (Tg) and thermal stability of the EP matrix. Compared to unmodified EP (EP-0), the Tg value and initial decomposition temperature of EP/ODDPO-1.2 decreased by only 7.6 °C and 10.0 °C, respectively. Moreover, the introduction of ODDPO significantly improved the hydrophobicity and water absorption resistance of epoxy materials, which is attributed to ODDPO's rigidity and symmetric structure, reducing water molecule permeation. Furthermore, the dielectric properties of ODDPO-modified EP samples were strengthened compared to EP-0, due to the ODDPO's symmetric structure reducing the polarity of the matrix. The above results indicated that ODDPO serves as an excellent flame retardant while enhancing other properties of the EP matrix, thereby contributing to the preparation and application of high-performance epoxy materials. [ABSTRACT FROM AUTHOR]

Recently, the influence of the concept of environmental sustainability has increased, which includes environmentally friendly measures related to reducing the consumption of petrochemical fuels and converting post-production feedstocks into raw materials for the synthesis of polymeric materials, the addition of which would improve the performance of the final product. In this regard, the development of bio-based polyurethane foams can be carried out by, among other things, modifying polyurethane foams with vegetable or waste fillers. This paper investigates the possibility of using walnut shells (WS) and the mineral fillers vermiculite (V) and perlite (P) as a flame retardant to increase fire safety and thermal stability at higher temperatures. The effects of the fillers in amounts of 10 wt.% on selected properties of the polyurethane composites, such as rheological properties (dynamic viscosity and processing times), mechanical properties (compressive strength, flexural strength, and hardness), insulating properties (thermal conductivity), and flame retardant properties (e.g., ignition time, limiting oxygen index, and peak heat release) were investigated. It has been shown that polyurethane foams containing fillers have better performance properties compared to unmodified polyurethane foams. [ABSTRACT FROM AUTHOR]

This study investigates the effects of inorganic flame retardants, zinc borate, and magnesium hydroxide, on the thermal, morphological, flame retardancy, and mechanical properties of polypropylene (PP)/calcium carbonate composites for potential construction industry applications. Polypropylene/calcium carbonate (50 wt.%) composites containing 5 and 10 wt.% flame retardants were prepared using a batch mixer, followed by compression moulding. The results demonstrated enhanced thermal stability, with the highest char residue reaching 47.2% for polypropylene/calcium carbonate/zinc borate (10 wt.%)/magnesium hydroxide (10 wt.%) composite, a notably strong outcome. Additionally, the composite exhibited an elevated limited oxygen index (LOI) of 29.4%, indicating a synergistic effect between zinc borate and magnesium hydroxide. The proposed flame retardancy mechanism suggests that the flammability performance is driven by the interaction between the flame retardants within the polypropylene/calcium carbonate matrix. Magnesium hydroxide contributes to smoke suppression by releasing water, while zinc borate forms a protective glassy foam that covers the burning surface, promoting char formation and acting as a physical barrier to heat transmission and fire spread. Scanning electron microscopy confirmed good dispersion of the additives alongside calcium carbonate within the polymer matrix. Despite the addition of up to 10 wt.% flame retardants, the composites maintained high-notched impact strength. [ABSTRACT FROM AUTHOR]

The flammability levels, flame retardancy ratings, and reaction-to-fire (fire response) properties (under five radiant heat fluxes, i.e., 15, 25, 35, 50, and 75 kW m−2) for same real E-glass fiber-reinforced unsaturated polyester resin (UPR) composite wind turbine blade (WTB) samples were determined by experimental techniques like limiting oxygen index (LOI), vertical flame test (VFT), and cone calorimeter test (CCT). Based on typical CCT results (main test parameters), thermal and non-thermal hazard assessment index systems were selected, calculated, and compared to deduce corresponding hazard characteristics of the blade samples. The WTB shows a LOI value of 25.10% (combustible) and a non-rated (NR) UL (Underwriters Laboratories) 94 classification according to the after-flame time criterion. CCT analyses indicate that higher external heat fluxes correspond to increased peak heat release rate (PkHRR), total heat release (THR), and mass loss rate (MLR) values, and reduced ignition time (tig), flame duration (tfl), and overall flame (combustion) duration (FD) values. Meanwhile, CCT analyses indicate that higher external heat fluxes result in elevated specific extinction area (SEA), rate of smoke released (RSR), total smoke released (TSR), CO yield (COY), and CO production rate (COP) values, and relatively lower CO2 yield (CO2Y) and CO2 production rate (CO2P) values. These results reflect real WTB fires will pose severe situations with noticeable thermal and non-thermal hazards. Multiple physical and chemical evolution processes undergo in burning processes of such fires with higher PkHRR values through heat releases, transfers, exchanges, and feedback. Composite blade materials may be largely deformed and disintegrated in faster rates. Burning blade blocks may form spotting fires and cause secondary ground fires. Local air quality, visibility levels, working, and health conditions of related persons may be worsened. It is really urgent to develop mature, effective, novel, and even revolutionary fire protection and suppression technologies for such fires. [ABSTRACT FROM AUTHOR]

Creating eco-friendly flame retardants (FRs) that are highly effective for textiles while requiring minimal quantities is crucial for both human well-being and environmental conservation. Traditionally, halogen FRs have been the mainstay in this field. Yet, due to their harmful impacts on both human health and the environment, there is a growing demand to discontinue their use. Herein, in this work, a novel eco-friendly intumescent-based flame retardant for cotton fabrics, consisting of ammonium polyphosphate (APP), single-walled carbon nanohorns (SWCNHs), and melamine (MEL) was explored. The addition of SWCNHs demonstrated a clear synergistic effect with APP and MEL in enhancing the flame retardancy of cotton fabrics. After four spraying cycles, the treated cotton fabric ASM4 demonstrated outstanding flame retardancy and self-extinguishing properties. Additionally, its LOI value could reach 24.1 ± 0.1% and the damage length dropped to 4.6 ± 0.2% cm from 30.0 ± 0.1% cm for the pristine cotton fabric, while preserving its original morphology with partial carbonization. The pHRR and THR of ASM4 were dramatically decreased by 90% and 51%, respectively in the cone calorimeter test. Moreover, investigating the thermal degradation kinetics of treated cotton fabric and the physicochemical properties of the char residues revealed the crucial influence of SWCNHs on improving the flame resistance of cotton fabrics. The incorporation of SWCNHs improved both the thermal stability and the degree of graphitization of the char layer, which served as a protective barrier. This barrier efficiently blocked the release of volatile combustible substances while allowing for the emission of nonflammable gases. This work provides a theoretical basis for the feasible application of SWCNHs in intumescent FRs. [ABSTRACT FROM AUTHOR]

In this study, the challenges of brittleness and flammability in Polyamide 6/glass fiber (PA6/GF) composites, which are crucial for heat‐resistant and stress‐bearing structural parts, are addressed. Polyphosphazene (PZ) elastomers, known for their exceptional flame‐retardant properties, are introduced to enhance the robustness and safety of these composites. Specifically, poly(diaryloxy)phosphazene (PDAP) and poly(difluoroalkoxy)phosphazene (PDFP) are utilized, both contributing to the improved toughness and flame resistance of the PA6/GF composites. Experimental results show that PDAP mainly played the role of solid‐phase flame retardant, while PDFP mainly acted the role of gas‐phase flame retardant. For PA/PZs composites without adding GF, PDFP plays a more efficient flame retardant effect than PDAP. By introducing 15 Vol% of PDFP, the limiting oxygen index (LOI) of the composite reached 26.1%, while the notched impact strength increased by 297%. For PA/PZs/GF composites, PDAP plays a better flame retardant role than PDFP. Under the action of 30 vol% GF and 15 vol% PDAP, the LOI of PA6/PDAP/GF composite reached 26.8%, and the notch impact strength improved to 18.7 kJ/m2, which is 165% higher than that of PA6/GF, and the UL‐94 test reaches V‐0 level. The findings of the study highlight the potential of PDAP and PDFP to act as dual‐function modifiers. These modifiers can considerably ameliorate both the impact resistance and flame retardancy of PA6 and PA6/GF composites. Such dual enhancement surpasses the typical trade‐offs seen in conventional composites, indicating a constructive direction for future material innovation. Highlights: Polyphosphazenes simultaneously enhance PA6's toughness & flame resistance.Distinct flame retardant mechanisms found in PDAP and PDFP.GF presence alters PDAP and PDFP's flame retardant efficacy.PDAP shows superior flame resistance in GF‐reinforced PA6 composites.Without GF, PDFP outperforms PDAP in enhancing flame retardancy. [ABSTRACT FROM AUTHOR]

The enhancement of flame resistance and mechanical strength is critical for the utilization of rigid polyurethane foam (RPUF) composites. In this study, the efficient synergistic flame‐retardant system, incorporating dimethyl methylphosphonate (DMMP) and expandable graphite (EG), with the addition of refined alkali lignin (A‐lignin) were aimed to superior fire resistance and mechanical integrity for RPUF. Furthermore, the flame retardancy and charring ability of obtained RPUF were obviously enhanced. Notably, an RPUF mixture containing A‐lignin, DMMP, and EG demonstrated substantial charring at elevated temperatures, improved limiting oxygen index, and met the UL‐94 V‐0 rating. Cone calorimeter test indicated that this formulation produces less heat and smoke than pure RPUF. The flame‐retardant efficacy of obtained RPUF was attributed to the formation of a protective char layer coupled with the free radical neutralization properties of DMMP, collectively enhancing the flame retardancy obtained RPUF. Additionally, this RPUF variant showed significant advancements in both mechanical and thermal performance. This study outlines a successful strategy for developing RPUF composites endowed with enhanced flame retardancy and mechanical strengths. [ABSTRACT FROM AUTHOR]