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[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]

Reducing the dependence of epoxy resin preparation on petroleum resources and developing thermosetting epoxy resins with excellent comprehensive performance are important directions for the current development of epoxy resins. This article uses biomass resource magnolol as the main raw material to prepare magnolol epoxy monomer (DGEM). Then, using 4,4-diaminodiphenylmethane (DDM) as the curing agent, the DGEM and bisphenol A epoxy resin (E44) were blended and cured. The results showed a dual modification effect of DGEM on the toughening and strengthening of E44 epoxy resin. When the mass ratio of DGEM to E44 is 30:70, the bending strength of the cured blended resin is 18.7% higher than that of the E44 system, and the tensile strength is 57.7% higher. When the mass ratio of DGEM to E44 is 5:95, the cured blended resin exhibits the optimal impact strength (5.10 kJ/mol), which is 22.9% higher than the pure E44 system. However, the addition of DGEM reduced the glass transition temperature and crosslinking degree of the blended resin system. The addition of DGEM improves the heat resistance and flame retardancy of the blended resin. When the mass ratio of DGEM: E44 was 50:50, the vertical combustion reached UL-94 V-0 level. [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]

In this work, different kinds of silane coupling agents modified expanded graphite (MEG) fillers were successfully prepared and then incorporated into silicon rubber matrix to fabricate flame‐retardant composite materials (SR/MEG). The inserted MEG fillers with siloxane chains exhibited good compatibility with the silicon rubber matrix, which cannot only reduce the negative impact of adding fillers on mechanical properties but also endow the silicon rubber composites with ideal flame retardancy. Subsequently, platinum (Pt) catalyst was incorporated into the SR/MEG composites to prepare SR/MEG/Pt composites, and the synergistic effects of MEG and Pt catalyst on the thermal stability, flame retardancy, and combustion behavior of silicon rubber composites were systematically investigated. The target SR/MEG/Pt composite with appropriate addition of MEG and Pt catalyst can obtain relatively high char residue of 41.9% and limiting oxygen index value of 29.6%, as well as achieve V‐0 rating in the vertical combustion test, owing to the formation of expanded and dense silicon–carbon protective layer under the catalysis of Pt catalyst. Moreover, the cone calorimeter test results showed that the peak of heat release rate and total heat release of SR/MEG composites were further reduced after the addition of an appropriate amount of Pt catalyst, manifesting the good synergistic effect of MEG and Pt catalyst on the flame retardancy performance of silicon rubber. The method proposed herein may provide a promising way for fabricating high‐performance flame‐retardant silicone rubber materials. [ABSTRACT FROM AUTHOR]

Poly (lactic acid) (PLA) bead foam has a promising application because of its renewable and naturally degradable nature. However, its processing is greatly limited by inherent shortcomings such as the complex polycrystals‐inducing strategy. Herein, we developed a strategy of bulk polymerization reaction of polyvinyl acetate (PVAc) to sinter PLA beads to prepare EPLA foams accompanied by supercritical CO2 foaming technology. In order to enhance the sintering behavior and flame‐retardancy of EPLA foams, two‐dimensional nanolayered double hydroxides (LDHs) were introduced and dispersed in the continuous phase of the sintering layers. The formation of unique dispersion of LDHs and sintering structure of PVAc generated substantial increase in the crystallinity, melt elasticity, and sintering strength of EPLA foams, which facilitated the growth and stabilization of cells. Thus, the cell‐density and expansion ratio could be increased to 8.62 × 106 cell/cm3 to 9.31‐fold, respectively. Moreover, the mechanical properties of the EPLA foams were improved. The tensile strength and the compression strength increased to 2.96 and 62.5 MPa. Additionally, with adding 7 wt.% LDH, the EPLA foam reached UL‐94 V‐0 rating with high limiting oxygen index value of 29.1% and char residue of 20.4%. This study provides a novel strategy for the preparation of flame‐retardant EPLA foams with low density, three dimensional complex shapes, as well as excellent mechanical properties. [ABSTRACT FROM AUTHOR]

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]

Plant protein‐based adhesives are gaining traction owing to their low cost and eco‐friendliness. However, achieving flame retardancy and long‐term water resistance in them under room‐temperature curing conditions remains a challenge due to the hydrophilicity and low reactivity of plant proteins. Herein, a novel adhesive synthesized from soybean meal (SM), activated sodium alginate (aSA), nano‐hydroxyapatite (nHA), and polyamidoamine‐epichlorohydrin (PAE) resin addresses this challenge. aSA as a reactive bio‐based cross‐linker formed covalent cross‐linking structures with SM matrix at room temperature, while the nHA‐induced biomineralization and PAE‐constructed supramolecular cross‐linking promote water drainage from the adhesive, preventing water erosion of the adhesive structure. The developed adhesive shows versatility across multiple substrates, with its wet shear strength on wood reaching 0.76 MPa, surpassing that of the commercial aldehyde‐based adhesive. The adhesive is effective over a wide temperature range from room temperature to 150 °C due to the reactivity of the PAE resin above 60 °C. Moreover, it exhibits excellent flame retardancy (limiting oxygen index of 31.2%) owing to its dense structure and the abundance of N‐containing and P‐containing components. This work is expected to break the monopoly of petroleum‐based adhesives in the realm of room‐temperature adhesives. [ABSTRACT FROM AUTHOR]

Toward addressing the aesthetic demand, IR emissivity, and fire hazards of radiative cooling materials in the practical application, chameleon‐inspired is tactfully employed, dipole moment‐increasing, and fire‐retardant strategies to manufacture an advanced polyurea‐based composite coating through incorporating thermochromic microcapsules, boron nitride nanosheets, and montmorillonite nanosheets. The chameleon‐inspired thermochromic microcapsules and admirable IR emissivity (supported by the original IR emittance spectra) realized by the increasing dipole moment allow the composite coatings to spontaneously adjust the solar absorption and reflection during hot daytime, while enabling high‐efficiency radiative cooling throughout the day. The IR emissivity higher than most literature is attributed to the strong interfacial interactions within polyurea composite coatings which improve the dipole moment of C─O─C, Si─O, and B─N bonds by increasing the distance between the centers of positive and negative charges, thus producing more IR emissions. Furthermore, the thermally melted montmorillonite nanosheets can form a ceramic protective layer enhanced by boron nitride nanosheets, further suppressing combustion behavior to improve the fire safety performance of polyurea coatings. The integration of thermochromic functionality, high fire safety, and admirable IR emissivity not only contribute to promoting the practical application of radiative cooling materials, but also provide a precious reference route to design high IR emissivity. [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]

The use of natural and synthetic textile materials in various industries is significant, but their flammability poses a risk in case of fire accidents. These textile materials contain a significant amount of carbon and hydrogen in their structure, which can act as fuel for combustion. As a result, these textile materials can be hazardous in the event of a fire accident. Therefore, the application of fire-retardant treatments to textile materials has great importance to mitigate fire risks. Despite the availability of numerous effective flame retardants for textile applications, there is a need to develop new environmentally friendly flame-retardant agents and treatments that are both effective and environmentally friendly. The application of flame-retardant compounds is evolving globally, considering modifications to textile surfaces and the use of environmentally friendly materials. Thus, this review focuses on the functionalization of textile materials with bio-based and eco-friendly flame retardants and reviews recent studies on the use of compounds such as phytic acid, lignin, eggshell, gelatin, chitosan, nanosized/nanomaterial, and phosphorus-containing flame retardants on natural and synthetic textiles. The review highlights bio-based and eco-friendly approaches and improvement of flame-retardant efficiency of textiles through synergistic interaction of phosphorus with other environmentally acceptable elements like nitrogen and silicon. [ABSTRACT FROM AUTHOR]

In modern society, with the rapid increase in energy consumption, there is a growing interest in the effective utilization of bio-resources. Biomass aerogels have considerable academic research value due to their eco-friendly attributes and renewable nature. In this work, sodium alginate (SA) and sodium lignosulfonate (SLS) are employed as the matrix, which are dually cross-linked with Ca2+ and bis[tetrakis(hydroxymethyl)phosphonium] sulfate (THPS). Subsequently, a well-formed aerogel (CA-SP) is obtained through the lyophilization process. The formed dual crosslinking network and the "egg-box" structure endow the CA-SP aerogel with superior flame retardancy and thermal insulation properties, as evidenced by a limiting oxygen index value of 40.8%, achievement of the UL94 V-0 rating and low total heat release (1.35 MJ·m−2). Moreover, the THPS simultaneously endows the SA-SP aerogel with excellent flame retardancy and antimicrobial effect. The exceptional flame retardancy, smoke suppression capabilities, and antimicrobial effects of the CA-SP aerogel expand its prospects for application. [ABSTRACT FROM AUTHOR]

In this study, a novel strategy is proposed to prepare eco-friendly flame-retardant cotton fabrics, where chloroacetic acid (MCA) and L-glutamic acid (L-Glu) are used as raw materials to enhance the chelation ability between carboxyl groups (-COO-) and calcium ions (Ca2+). The morphological and structural characterizations of the prepared cotton fabrics indicate that the three free hydroxy groups (2, 3, 6) in the cellulose macromolecule are chemically modified to graft a large number of carboxyl groups, and Ca2+ ions are successfully chelated on the surface of cotton fabric. The thermal stability of cotton fabrics is greatly improved in both air and nitrogen atmosphere. The residual mass of flame-retardant cotton fabric (COT-Glu–Ca) is much higher than that of original cotton fabric, increasing from 0.03% to 5.6% in air and from 8.1% to 28.2% in N2, respectively. At the same time, the limiting oxygen index (LOI) of COT-Glu–Ca fabric is as high as 33.6%. The prepared flame-retardant cotton fabric can undergo vertical combustion tests with a char length of only 53 mm, and afterflame and afterglow are not observed, which proves that the grafted cotton fabric had a good flame retardancy due to a series of modifications and adsorption of Ca2+ ions. The properties of the cotton fabric, including tensile strength, whiteness, and moisture absorption, are all retained at a satisfactory level. Overall, this study provides a promising strategy for manufacturing eco-friendly, phosphorus-free, halogen-free, and fire-resistant cotton fabrics with enhanced metal ion chelation ability. [ABSTRACT FROM AUTHOR]

Polyether ether ketone (PEEK) sulfonation process is a reasonably easy but time‐consuming to manufacture composites. This study focuses on altering PEEK powder in a sulfuric acid solution via a sulfonation process to develop sulfonated PEEK (SPEEK) resin for the fiber‐reinforced thermoplastic composite manufacturing and characterization steps. In this study, about 5 wt% PEEK powder was sulfonated in 98% sulfuric acid solution for 12 h at 65°C. The water bath technique was used for the precipitation process to obtain the SPEEK polymer. After proper washing and drying, the SPEEK matrix (resin) was obtained by dissolving it in dimethylformamide in a ratio of 1:2. This resin solution was then used to manufacture thermoplastic Kevlar and glass fiber‐reinforced composites employing wet layup process and cured at an elevated temperature under pressure. These SPEEK composites passed the flame retardancy UL94 test with a V0 rating. The average water contact angle of the glass fiber‐ and Kevlar‐SPEEK composites is 93.67° and 102.24°, respectively. The average tensile strength values of these composites were found 222.22 and 284.35 MPa, correspondingly. The smoke density and toxicity tests of the glass fiber‐SPEEK composite confirmed lower smoke generation with the modifications. These SPEEK‐fiber composites can be considered for various industrial applications, including aviation, energy, drone, defense, and automotive. [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]

Simultaneously improving the thermal conductivity and flame resistance of epoxy composite is still a challenge. Herein, a novel epoxy composite with high thermal conductivity and greatly enhanced flame retardancy was developed through constructing integrated three-dimensional (3D) network based on boron nitride (BN), talc, ammonium polyphosphate (APP). The thermal conductivity of the composite with filler network reached 3.04 Wm−1K−1, which was 15.2 and 3.1 times of those of pure epoxy and sample with random filler distribution. The LOI value of the composite with filler network reached 37.8%, which was 1.9 and 1.4 times of those of pure epoxy and sample with random filler distribution, respectively. In addition, the effects of various combinations of filler on the flame resistance of the epoxy composite were also evaluated. The prepared composite with filler network exhibited excellent shape stability and mechanical strength even after ablation at 1000°C. The network structure constructed by BN had a positive effect on heat transfer, while APP led to the formation of phosphoric acid at high temperature, adhering to talc and other residues together. A ceramic-like residue was formed on the firing surface, which enhanced the barrier effect of char layer and flame resistance of the composite. [ABSTRACT FROM AUTHOR]

Green and facile route was employed for development of smart flame-retardant, antibacterial and reinforced textile fabric's coatings. The multifunctional coatings were fabricated from sustainable chitosan functionalized via one pot method with α-aminophosphonates with different groups (methyl and phenyl groups). Phenyl- and methyl-based α-aminophosphonates were grafted on chitosan chains individually. Additionally, magnetic chitosan-Fe3O4 nanoparticles functionalized α-aminophosphonates-based phenyl moiety were also prepared. Moreover, tetra-n-butylammonium hexafluorophosphate was also dispersed in coating dispersion. The different prepared functionated chitosan was then exploited as efficient flame-retardant, reinforced and antibacterial-based multifunctional coatings for cotton fabrics. Different mass loadings of methyl- and phenyl-based functionalized chitosan and magnetic chitosan were dispersed in chitosan solution and then coated on cotton surface. The influence of mass loading and different side groups was studied. Flammability, tensile strength and antibacterial properties of developed cotton fabrics were evaluated. The flammability of coated cotton fabrics was strongly improved achieving reduction in rate of burning by 48% compared to uncoated one. This is in addition to LOI value of 23.5% compared to 18% for uncoated fabric. This is due to the influence of organic phosphate in coating layer which stimulates the formation of protective char layer. The tensile strength of coated fabrics was improved recording 29% enhancement compared to uncoated one. Moreover, the developed coating layer strongly inhibits the growth of well-known bacterial strains Escherichia coli and Staphylococcus aureus, achieving clear antibacterial inhibition zones of 16.7 and 23.6 mm, respectively. Additionally, the flame retardancy mechanism was proposed and elucidated. [ABSTRACT FROM AUTHOR]

Aiming at settling the critical problems of ecological and environmental safety caused by traditional halogen-containing and phosphorus-containing flame-retardant system, this paper has fabricated a transition metal manganese ion (Mn2+) loaded diatomite (Mn@DE) via a simple chemical modification process, which can be employed as raising the flame retardancy of silicone rubber (SR). Compared with traditional flame retardants, the unique lamellar shielding ability and Mn-enhanced catalytic charring ability from designed mineral-based flame retardants are conductive to upgrading the flame-retardant level of silicone rubber/Mn-modified diatomite (SR/Mn@DE) composites. The results demonstrate that when the amount of Mn@DE reaches 30 phr in the composites, the limiting oxygen index (LOI) and vertical combustion tests of SR/30 phr Mn@DE can reach 27.3% and UL-94 V-0 ratings, respectively. Simultaneously, the reduction for peak heat release rate (PHRR) and total heat rate (THR) of SR/Mn@DE can achieve 55.3% and 66.1%, revealing that the fire hazard of SR has been effectively decreased. Thermogravimetric analysis (TGA) has enlightened that the introduction of Mn onto diatomite can effectively reinforce the thermal stability and char-forming ability of SR composites. Through the systematic analysis for combustion residues, the condensed flame-retardant mechanism of SR/Mn@DE via restraining the heat transfer and fuel feedback can be primarily inferred. Therefore, this paper have provided a fast and practical flame-retardant strategy in order to discarding the halogen-/phosphorus-containing flame retardants, which will open up the key problem of limited application for SR composites in more fields. [ABSTRACT FROM AUTHOR]

Fluorosilicone was combined with aluminum trihydrate (ATH) to induce synergistic flame-retardant and thermal-resistant properties. The surface of ATH was modified with four different silane coupling agents. The flammability and mechanical properties of the fluorosilicone/ATH composites were assessed using an UL94 vertical test and a die shear strength test. The change in shear strength was investigated under aging for 1000 h at −55 °C and 150 °C. Pure fluorosilicone had inherent fire resistance and thus achieved a V-0 rating even at 20 wt.% ATH loading. Upon addition of ATH treated with 3-glycidoxypropyl trimethoxysilane, the composites exhibited the highest shear strength of 3.9 MPa at 23 °C because of the additional crosslinking reaction of fluorosilicone resin with the epoxide functional group of the coupling agent. Regardless of the types of coupling agents, the composites exhibited similar flame retardancy at the same ATH content, with a slight reduction in shear strength at 180 °C and 250 °C. The shear strength of the adhesives gradually decreased with aging time at −55 °C, but increased noticeably from 3.9 MPa to 11.5 MPa when aged at 150 °C due to the occurrence of the additional crosslinking reaction of fluorosilicone. [ABSTRACT FROM AUTHOR]

Silicone rubber (SR), as one kind of highly valuable rubber material, has been widely used in many fields, e.g., construction, transportation, the electronics industry, automobiles, aviation, and biology, owing to its attractive properties, including high- and low-temperature resistance, weathering resistance, chemical stability, and electrical isolation, as well as transparency. Unfortunately, the inherent flammability of SR largely restricts its practical application in many fields that have high standard requirements for flame retardancy. Throughout the last decade, a series of flame-retardant strategies have been adopted which enhance the flame retardancy of SR and even enhance its other key properties, such as mechanical properties and thermal stability. This comprehensive review systematically reviewed the recent research advances in flame-retarded SR materials and summarized and introduced the up-to-date design of different types of flame retardants and their effects on flame-retardant properties and other performances of SR. In addition, the related flame-retardant mechanisms of the as-prepared flame-retardant SR materials are analyzed and presented. Moreover, key challenges associated with these various types of FRs are discussed, and future development directions are also proposed. [ABSTRACT FROM AUTHOR]

The application of warm-mix flame retardant rubber asphalt (WFRA) in tunnel pavement offers a promising solution that enhances both energy conservation and tunnel safety. First, a commercial halogen-free flame retardant (ZK), alumina trihydrate (ATH), and organic montmorillonite compound ATH flame retardant (OMMT/ATH) were melt-blended with warm-mix rubber asphalt (WRA) to prepare different types of WFRAs. Then, the effects of various flame retardants (FRs) on flame retardancy and rheological properties of the WRA were evaluated. Moreover, the functional groups of FR, WRA, and WFRA were investigated. Finally, the synergistic mechanism of FR on the WRA was explored based on the analysis of flame retardancy, rheological properties, and functional groups. Results show that the flame-retardant effect of OMMT/ATH on the WRA is much better than that of single FRs (ZK and ATH), indicating that the OMMT and ATH exhibit synergistic flame-retardant effect. The addition of OMMT/ATH enhances the high-temperature performance but shows little effect on the fatigue performance of the WRA. The synergistic flame-retardant mechanism of OMMT/ATH on the WRA is mainly attributed to the physical barrier effect of OMMT, the cooling and dilution effect of ATH, and the synergistic covering layer effect of OMMT and ATH. [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]

This study examines the evolution and potential of halogen-free polymers, highlighting recent advancements in alternatives and their environmental advantages. The integration of these flame retardants within polymer composites is addressed, focusing on how novel materials and methods can improve mechanical properties without compromising fire safety. Sustainability is a key consideration, with life cycle assessments demonstrating the environmental benefits of halogen-free polymers. The crucial role of these polymers in the electronics, transportation, and aerospace sectors is also explored, emphasizing their exceptional flame-retardant capabilities and specific performance requirements. This review identifies key challenges and promising research avenues for further development in the field of halogen-free polymers. It underscores the need for continuous development and collaboration to ensure the future of polymer science embraces sustainability and fire safety without compromise. This comprehensive review aims to equip researchers and scientists with a thorough understanding of halogen-free polymers, paving the way for advancements toward a future characterized by both responsible material development and effective fire protection. Exploreshalogen-free polymers' evolution, properties, and applications. Discusses recent advances in flame-retardant polymer development. Stresses flame retardant inclusion to boost composite properties. Highlights sustainability and environmental impact assessments. Examineshalogen-free polymers' role in electronics, transport, aerospace. Advocates for ongoing innovation and collaboration in research. [ABSTRACT FROM AUTHOR]

Transparent wood has the potential to be a sustainable alternative to glass in the building and construction industry. However, it is crucial to consider the fire hazard in building applications. In this study, we applied a green strategy to treat the wood aerogel with an intumescent flame retardant coating. The coating consisted of positively charged polyethyleneimine (PEI) and melamine, as well as negatively charged phytic acid. The treated wood aerogel demonstrated excellent flame retardancy. Subsequently, we incorporated the flame-retardant wood aerogel into epoxy resin to examine its impact on the thermal stability and fire resistance of the epoxy. The wood aerogel, with two bilayers of PEI + melamine/phytic acid, significantly enhanced the fire resistance of the epoxy. This was evident through notable reductions in peak heat release rate (42%) and total heat release (15%). By characterizing the char residue of the epoxy/wood-2 composite, we observed the formation of a continuous network within the epoxy matrix, effectively impeding the transfer of combustible gases and heat. Our work presents a simple and environmentally friendly approach to producing multifunctional transparent wood. [ABSTRACT FROM AUTHOR]

Conventional thermosetting polymers, mostly derived from nonrenewable petroleum resources, are not reprocessable and recyclable due to their highly cross-linked three-dimensional networks and face the disadvantage of high flammability. To solve these issues, in this study, we synthesized a novel Schiff base covalent adaptable thermoset from a furan-derived tri-aldehyde monomer (TMFP) and a furan-derived di-amine monomer (DFDA). The as-prepared TMFP-DFDA-Vitrimer exhibited superior anti-flammability with a high limiting oxygen index (LOI) of 35.0% and a UL-94 V-0 rating, which was attributed to the excellent charring ability. Additionally, TMFPDFDA-Vitrimer could also be conveniently recycled by chemical decomposition under a mixed hydrochloric acid/tetrahydrofuran (HCl/THF) solution. After recycling for 5 times, the thermal, mechanical, and flame retardant properties of the recycled TMFP-DFDA-Vitrimer retained almost unchanged compared to the original one. This work provides a prime instance to develop advanced thermosetting polymers from abundant furan-based compounds. [ABSTRACT FROM AUTHOR]

It is difficult to effectively manage the emission of harmful smoke from flame‐retardant modified epoxy resins (EP). In order to solve this difficulty, a highly efficient flame‐resistant PAD containing phosphorus, nitrogen, and sulfur was synthesized using a simply one‐pot method employing 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO), 2‐amino‐5‐mercapto‐1,3,4‐thiadiazole (AMT), and terephthalaldehyde for not only enhancing its flame retardant properties but also effectively suppressing the emission of fumes. Results have confirmed that the incorporation of 5 wt% flame retardant into the EP successfully passed the UL‐94 V‐0 rating, besides 24.2% reduction in the peak of smoke produce rate (PSPR), with outstanding fire‐resistant properties and effectively reduce smoke emissions. In addition, incorporating 7.5% of PAD into EP increased its flexural strength and modulus, from 78.4 and 2917.5 to 86.6 and 3162.9 MPa, respectively. Due to the abundance of reactive groups including sulfhydryl and secondary amine in PAD, as well as the nitrogen atoms presented in the thiadiazole and benzene rings of the phosphaphenanthrene structure, which could create hydrogen bonds with the matrix and participated in π‐π interactions, therefore, the mechanical properties of flame retardant epoxy resin (FREP) were greatly enhanced. [ABSTRACT FROM AUTHOR]

Waterborne polyurethane (WPU), which is a novel and environmentally friendly variety of polyurethane, replaces organic solvents with water. It has been extensively utilized in diverse fields encompassing coatings, textile finishing, building decoration, adhesives, plastic chemistry, and others. However, WPU is inherently flammable and releases a significant amount of smoke production during the combustion process. This research presents an original fire‐resistant Waterborne Polyurethane (WPU) with a newly‐integrated flame‐retardant component comprising a triazine phosphoramidate segment derived from 9,10‐dihydro‐9‐oxo‐10‐phosphaphenanthrene‐10‐oxide (DOPO) within its primary structure. In comparison to pure WPU, the limiting oxygen index (LOI) of flame‐retardant WPU (FRWPU) increased from 19.6% to 29.2%. In UL‐94 testing, the FRWPU film achieved a V‐0 rating with only 6% retarding component. Additionally, in cone calorimetry tests, Total Heat Release (THR), peak Heat Release Rate (pHRR), Total Smoke Production (TSP), Smoke Production Rate (SPR), and peak Carbon Monoxide Production Rate (pCOP) are decreased by 27.7%, 16.2%, 64.6%, 61.3%, and 77.8%, respectively. The greater degree of graphitization observed in the residual carbon substantially impeded heat exchange and the emission of smoke during combustion. Flame‐retardant intermediate segments greatly improved the FRWPUs' ability to suppress smoke and remain flame‐retardant. The creation and formulation of aqueous polyurethanes that are flame‐retardant can benefit greatly from the insights and references offered by this research. [ABSTRACT FROM AUTHOR]

The ecological benefits and concerns surrounding fossil fuels had led to increased interest in bio-based rigid polyurethane foam (RPUF). Nonetheless, due to its flammability, it had limited application in various fields. To solve this problem, a green bio-flame retardant, cobalt hydroxystannate (CoSn(OH)6), was prepared and compounded with montmorillonite (MMT) and chick feather protein (CF), and applied to RPUF, which not only realized the regeneration of resources, but also provided RPUF with better thermal stability, flame retardancy and smoke suppression properties. The experimental results showed that when 3 wt% CoSn(OH)6 was added, the RPUF (CF1/MMT3/Co3) had the greatest activation energy. In addition, the peak heat release rate (PHRR) and total heat release (THR) of CF1/MMT3/Co3 decreased by 12.73%, and 11.16% respectively, compared with no CoSn(OH)6. In addition, its Ds decreased by 28.9% and the light transmittance increased by 17.6% compared with the RPUF without CoSn(OH)6. At the same time, its peak smoke production rate (PSPR) and the total smoke release (TSR) decreased by 25% and 18%. And CF1/MMT3/Co3 also had the lowest fire risk evaluation index. This study presented possibilities for practical utilization of the RPUF substances founded on bio-based flame inhibitors. [ABSTRACT FROM AUTHOR]

This study presents a novel approach to fabricate 3D‐printed phosphorous‐based acrylate monomers using stereolithographic 3D printing technology, aiming to create demonstrators with exceptional shape‐memory characteristics and robust flame retardant properties. The synthesized materials combine the advantages of 3D printing precision with the intrinsic flame retardancy of phosphorous‐based monomers, offering a versatile solution for applications requiring both shape memory functionality and fire resistance. The limiting oxygen index (LOI) value of the intrinsically flame‐retardant shape‐memory polymer (IFR‐SMP) can reach 34%, and the vertical combustion rating after UL 94 can obtain V‐0. The mechanism of the IFR‐SMP flame retardant mainly includes terminating a free‐radical chain reaction and gas phase dilution, which indicates that the gas‐phase mechanism plays an important role in the flame retardancy. This work advances the frontiers of 3D printing technology by demonstrating the synergistic potential of shape memory and flame retardancy within a single material system, providing a pathway toward the development of innovative and resilient materials for the future. [ABSTRACT FROM AUTHOR]

In this paper, preoxidized fibers, flame-retardant acrylic fibers and polyphenylene sulfide (PPS) fibers were chosen to prepare thermal insulation felts by the spunlaced process. The preparation of thermal insulation felts by single-component fibers, bicomponent fibers and multi-component fibers was studied. The breaking strength of the single fibers, flame retardancy, thermal conductivity, air permeability, thermal stability, shrinkage rate after washing, and the breaking strength of the thermal insulation felts were characterized. The results show that, for the single-component felts, preoxidized fiber felt had a longitudinal char length of only 35 mm, which was less than that of flame-retardant acrylic fiber felts and PPS felts. However, its longitudinal breaking strength was only 39.8 N. The bicomponent thermal insulation felt, blended with flame-retardant acrylic fibers and preoxidized fibers, had a higher breaking strength than the single-component felt, but it had char lengths greater than 100 mm after the vertical burning test. When the ratio of the multi-component insulation felts (preoxidized fibers, PPS fibers and flame-retardant acrylic fibers) was 35:60:5, the felt's longitudinal char length measured 23 mm, which was less than that of the aramid felt 72 mm. This felt's thermal conductivity was 0.0515 W/mK. It had an air permeability of 1995 mm/s, and the longitudinal dimensional shrinkage rate following the thermal stability test was only 1.1%. Multi-component thermal insulation felts are very important for the development of high-performance firefighting protective clothing. [ABSTRACT FROM AUTHOR]

Aramid fiber/epoxy resin (AF/EP) composite has been heavily used as an impact protection material due to its excellent mechanical properties and lightweight merits. Meanwhile, it is also necessary to concern the flammability of matrix resin and the wick effect of aramid fiber, which would constitute a fire risk in harsh environments. In this work, a multifunctional flame-retardant modifier (EAD) was incorporated into the AF/EP system to improve the flame retardation. The addition of 5 wt% EAD made the AF/EP composite exhibit a high limiting oxygen index (LOI) value of 37.5%, self-extinguishment, as well as decreased total heat release and total smoke release. The results from thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA) demonstrated that the treated composites maintained good thermal stability. Due to the combined action of covalent and noncovalent bonds in the matrix-rich region, the interfacial bonding improved, which endowed AF/EP composite with strengthening and toughening effects. Compared with the control sample AF/EP, the tensile strength and ballistic parameter (V50) of the sample with 5 wt% EAD increased by 17% and 10%, accompanied with ductile failure mode. Furthermore, the flame-retardant mechanism was obtained by analyzing the actions in condensed and gaseous phases. Thanks to good compatibility and interfacial adhesion, the incorporation of EAD solved the inconsistent issue between flame retardancy and mechanical properties, which further expanded the application of AF/EP composite in the protection field. [ABSTRACT FROM AUTHOR]

The burning of Ethylene–Propylene–Diene Monomer (EPDM) rubber generates substantial smoke, posing a severe threat to the environment and personal safety. Considering the growing emphasis on safety and environmental protection, conventional non-smoke-suppressing flame retardants no longer satisfy the present application requirements. Consequently, there is an urgent need to develop a novel flame retardant capable of suppressing smoke formation while providing flame retardancy. Sepiolite (SEP), a porous silicate clay mineral abundant in silica and magnesium, exhibits notable advantages in the realm of flame retardancy and smoke suppression. This research focuses on the synthesis of two highly efficient flame-retardant smoke suppression systems, namely AEGS and PEGS, using Enteromorpha (EN), graphene (GE), sepiolite (SEP), ammonium polyphosphate (APP), and/or piperazine pyrophosphate (PPAP). The studied flame-retardant systems were then applied to EPDM rubber and the flame-retardant and smoke suppression abilities of EPDM/AEGS and EPDM/PEGS composites were compared. The findings indicate that the porous structure of sepiolite plays a significant role in reducing smoke emissions for EPDM composites during combustion. [ABSTRACT FROM AUTHOR]

Fiber-reinforced polymeric composites have been extensively used in different industrial applications because of their excellent mechanical and other properties but have lower tolerance levels for fire and lightning damage. The thermal, mechanical, and electrical conductivity of these composites can be substantially increased using some thin metallic films for higher fire resistance. The objective of this study was to develop fire-retardant fiber-reinforced composites using modified resins and metallic copper (Cu) thin films and test and characterize the mechanical and thermal properties of these prepared composites. Standard hand wet layup process was used to manufacture composite panels, and then the flame retardant and other physical and chemical properties were determined before and after resin modification and surface metal film coatings. These modified resins and the conductive metallic films of the composite provided superior flame retardancy and higher mechanical strength. The prepared composite panels made from modified epoxy via 9,10-dihydro-9-oxo-10-phosphaphenanthrene-10-oxide (DOPO) inclusion and with metallic surface coatings passed the UL-94 vertical flame testing with a V-0 rating. This composite achieved an average flexural strength of 344.2 MPa, a mean tensile strength of 400.82 MPa, and a shear strength of 6.54 MPa for single lap shear joint studies. Fractography results also show better bonding of the matrix and fiber with no significant damage. This study may open new opportunities in various composite industries. [ABSTRACT FROM AUTHOR]

With rapid advances in electronic and communication technology, electromagnetic interference and other problems are becoming increasingly prominent. Thus, electromagnetic interference shielding materials have recently garnered extensive attention. In this study, a multi‐walled carbon nanotube/polyurethane/non‐woven electromagnetic shielding material (CPNW) is developed using impregnation and nonsolvent‐induced‐phase separation techniques. Utilizing a three‐dimensional nonwoven network as the substrate, the "nonwoven fabric‐polyurethane‐carbon nanotube" composite is impregnated and cured via the non‐solvent‐induced‐phase separation method, resulting in a distinctive porous dual‐network structure that ensures robust interfacial bonding between carbon nanotubes, nonwoven fabric, and polyurethane. At a carbon nanotube content of 10% (based on the mass of nonwoven fabric), CPNW exhibited an electromagnetic interference shielding effectiveness of 28.8 dB, a thermal conductivity of 0.127 W m−1 K−1, and a burning time of 1 min and 15 s, demonstrating outstanding electromagnetic shielding, flame retardant, and infrared stealth capabilities. Overall, this study laid a theoretical groundwork for the development of multifunctional non‐woven electromagnetic shielding materials with widespread application potential in aerospace, military, artificial intelligence, and wearable electronics. [ABSTRACT FROM AUTHOR]

This study aimed to improve the flame retardancy and mechanical properties of bacterial cellulose (BC) by introducing cereal proteins, namely zein and gluten. The production conditions were determined by observing residual masses of samples at 1000 ℃ using thermogravimetric analysis (TGA). According to the TGA results, the optimized production conditions for the BCs with zein and gluten were combined solvent exchange and entrapment of 20 weight% (wt.%) of zein, and entrapment of 40 wt.% of gluten, respectively. Surface characterization of BC prepared with zein and gluten under the optimal conditions confirmed that the cereal proteins were incorporated into the BC nanostructures via solvent exchange and/or entrapment and the original chemical and crystal structures of BC were not significantly changed. Limiting oxygen index (LOI) analysis confirmed that cereal proteins improved the flame retardancy of BC. In particular, the LOI of BC entrapped with gluten was 50%, which was better than that of cowhide leather. Char morphology analysis confirmed that the as-produced BCs with cereal proteins exhibited condensed-phase flame-retardant mechanism by forming intumescent chars. Analysis of the mechanical properties confirmed that compared with cowhide leather, as-produced BCs with cereal proteins possessed high tensile strength and dimensional stability, making them suitable leather substitutes. [ABSTRACT FROM AUTHOR]

The research progress, existing problems and future development of flame retarding modification of bio-based polyurethane are summarized. The work summarized the research status of commonly used methods for preparing bio-based polyurethane, including basic characteristics, application effect and development prospect of various flame retardant agent. At present, vegetable oil-based polyols can effectively replace traditional industrial synthetic petroleum-based polyols as raw materials for the synthesis of bio-based polyurethane. However, there are still some shortcomings in this area that have not been addressed. The defects of polyurethane, such as flammability and smokiness, need to be improved. The practical application conversion rate of research results was not high. The environmental protection and safety performance of bio-based polyurethane can be further improved and enriched. Therefore, more efforts should be put into the above questions, which were all of great significance to the development of polyurethane. The research on retarding modification of polyurethane will have great development space and application value in the future. [ABSTRACT FROM AUTHOR]

Ammonium polyphosphate (APP) and self-made nickel phytate (PANi) were used as modified materials to prepare green biomass rigid polyurethane foam (RPUF). The flame retardancy, thermal stability, smoke toxicity and mechanical properties of the modified RPUF were investigated by limiting oxygen index (LOI), a cone calorimetry (CONE) test, thermogravimetric analysis and a compression test. The results showed that the RPUF with 10 wt% APP (PANi/APP10) had the highest LOI of 26.5%. Its peak heat release rate (PHRR) and total heat release (THR) were reduced by 29.64% and 24.05% compared with PANi/APP0 without APP. And its smoke production rate (SPR) and total smoke release (TSR) decreased by 33.14% and 19.88%, respectively. Compared with pure RPUF, the compressive strength of PANi/APP10 was increased by 50%, mainly because APP itself was an ultra-fine powder, which was better compatible with the matrix and improved the hardness of the material. The results showed that the synergistic effect of the gas phase and the condensed phase mechanism could effectively improve the flame-retardant effect. The current research results provided a new strategy for the preparation of green and low-toxicity RPUF. [ABSTRACT FROM AUTHOR]

Epoxy sheet molding compound (ESMC) composites have excellent mechanical properties, dimensional stability and electrical insulation, and are widely used in the automotive industry. In our previous work silane coupling agent modified, hollow glass microspheres (SiHGM) and montmorillonite (MMT) were incorporated to enhance the mechanical properties of the ESMC composites. It was found that the ESMC composites containing MMT (EP/SiHGM/MMT-1) exhibited excellent mechanical strength. However, the flammability of the epoxy resin (EP) limits the use of ESMC composites for applications that require good flame retardancy. In this paper we describe our research in which MMT was used to increase the flame retardancy of ESMC composites. The results showed that the addition of MMT made the ESMC composites have excellent flame retardancy. The limiting oxygen index (LOI) of the ESMC composites containing 1 phr MMT (EP/SiHGM/MMT-1) was 26.8%, which was 8.94% higher than that of the ESMC composites without MMT (EP/SiHGM/MMT-0). In addition, the peak heat release rate (PHRR), average heat release rate (AHRR) and total heat release (THR) of the EP/SiHGM/MMT-1 were 322.8 kW/m2, 95.3 kW/m2 and 38.6 MJ/m2, respectively, which were 22.6%, 8.2% and 8.0% lower than those of EP/SiHGM/MMT-0. The carbon monoxide production (COP) and carbon dioxide production (CO2P) of EP/SiHGM/MMT-1 were 0.0092 g/s and 0.2071 g/s, respectively, which were 34.3% and 22.8% lower than those of EP/SiHGM/MMT-0. The fire growth index (FGI) of EP/SiHGM/MMT-1 was 2.4, which was a decrease by 29.4% compared to EP/SiHGM/MMT-0. In addition, the flame retardant mechanisms were revealed. We suggest that MMT promoted dehydration and charring of the epoxy resin and helped construct an intact physical barrier, which had good blocking effects. The prepared composite has great application prospects for those occasions that require high flame retardancy. Thus, this work provides an innovative strategy for preparing low density epoxy composites with excellent flame retardancy and high mechanical properties. [ABSTRACT FROM AUTHOR]

Furfurylated wood exhibits excellent dimensional stability and corrosion resistance, making it a promising material for constructing buildings, but it is highly flammable. Herein, flame-retardant furfurylated poplar wood was produced via a two-step process utilizing boric acid (BA) and ammonium dihydrogen phosphate (ADP) as flame-retardant components, and biomass-derived furfuryl alcohol (FA) as a modifier. The acidity of BA and ADP allowed them to catalyze the polymerization of FA, which formed a cross-linked network that immobilized BA and ADP inside the wood. The addition of BA/ADP substantially delayed the time to ignition from 10 to 385 s and reduced the total heat release and total smoke release by 58.75% and 77.31%, respectively. Analysis of the pyrolysis process showed that the decomposition products of BA and ADP protected the underlying furfurylated wood and diluted combustible gases. This method significantly improved the fire retardancy and smokeless properties of furfurylated wood, providing promising prospects for its application as an engineering material. [ABSTRACT FROM AUTHOR]

In this study, environmentally friendly and low-cost biomass materials were selected as wood flame retardants. Three polyelectrolyte flame-retardant coatings made from chitosan (CS), tea polyphenols (TP), soybean isolate protein (SPI), and banana peel powder (BBP) were constructed on wood surfaces by layer-by-layer (LBL) self-assembly. The results of SEM-EDS and FT-IR analyses confirmed the successful deposition of CS-TP, CS-SPI, and CS-BPP on the wood surface, and the content of N element increased. The TG results showed that the initial decomposition temperature and the maximum thermal decomposition temperature of the coated wood specimens decreased, while the char residue increased significantly. This is due to the earlier pyrolysis of CS-TP, CS-SPI, and CS-BBP. This shows that the three polyelectrolyte flame-retardant coatings can improve the thermal stability of wood. The combustion behavior of the wood specimen was observed by exposure to combustion; the coated wood could self-extinguish within a certain period of time after ignition, and the flame-retardant performance was improved to a certain extent. SEM and EDS characterization analyses of the carbon residue after combustion showed that the coated wood charcoal layer was denser, which could effectively block heat and combustible gas. [ABSTRACT FROM AUTHOR]

Carbon-based conductive polymer composites have attracted wide attention as candidates for high-performance flexible electric heaters. Herein, a poly(m-phenylene isophthalamide) (PMIA)/carbon black (CB) composite is proposed as electric heating films that can successfully realize stable and safe operation at high temperatures of > 200°C under a safe voltage as low as 20 V. The conductive filler content has a significant effect on the microstructure and electrical properties of the PMIA/CB composites. An optimized CB content of 20 wt.% in the PMIA polymer matrix not only guarantees uniform spatial dispersion, but also provides sufficient and stable conductive networks. As a result, the PMIA/CB composites present high heating temperature, rapid heating ability, good heating uniformity, and excellent heating reliability. Meanwhile, taking advantage of the high thermal stability, superior mechanical strength, and excellent flame retardancy of the PMIA polymer matrix, the PMIA/CB composites exhibit superior thermal endurance and self-extinguishing capabilities, leading to significantly enhanced operating safety. This study will open new avenues for the development of high-performance electrothermal composite films for medium- to high-temperature applications. [ABSTRACT FROM AUTHOR]

Green manufacturing and reducing our cultural dependency on petrochemicals have been the global interest currently, especially in the polyurethane industry segments. We report the fabrication of rigid polyurethane foams (RPUFs) and their flame-retardant property from hemp seed oil as an alternative to petrochemical-based polyols. The cold-pressed hemp-seed oil (HSO) was first oxidized to epoxidized triglyceride oils with acetic acid and hydrogen peroxide, followed by a ring-opening reaction with methanol to fabricate hemp bio-polyols. The formation of polyols was characterized using FT-IR, hydroxyl, and acid values. The bio-polyol was used in different proportions with commercial polyols and other foaming ingredients to produce rigid polyurethane foams via a one-step process. Dimethyl methylphosphonate (DMMP), triethyl phosphate (TEP), and expandable graphite (EG) were added during the foam preparation to improve flame retardancy. The produced foams were analyzed for their apparent density, mechanical properties, thermal degradation behavior, closed cell content, flammability, and cellular morphology. The effect of different flame retardants had a significant influence on the cellular structures, closed-cell content, density, and compressive strength of the polyurethane. A significant improvement in anti-flaming properties was observed as the neat HSO-based foam showed a burning time of 110 s and a weight loss of 82%, whereas 10 wt% of TEP displayed a reduced burning time and weight loss of 19 s and 5%, respectively. DMMP and EG-based RPUFs exhibited similar flame retardancy and mechanical properties relative to neat HSO-based foam. The results demonstrated in this work proposed a potential combination of bio-polyols and commercial polyols as a strategy to fabricate flame-retardant polyurethane foam for high-performance applications. [ABSTRACT FROM AUTHOR]

The incorporation of commercial flame retardants into fiber-reinforced polymer (FRP) composites has been proposed as a potential solution to improve the latter’s poor flame resistance. However, this approach often poses a challenge, as it can adversely affect the mechanical properties of the FRP. Thus, balancing the need for improved flame resistance with the preservation of mechanical integrity remains a complex issue in FRP research. Addressing this critical concern, this study introduces a novel additive system featuring a combination of one-dimensional (1D) hollow tubular structured halloysite nanotubes (HNTs) and two-dimensional (2D) polygonal flake-shaped nano kaolinite (NKN). By employing a 1D/2D hybrid kaolinite nanoclay system, this research aims to simultaneously improve the flame retardancy and mechanical properties. This innovative approach offers several advantages. During combustion and pyrolysis processes, the 1D/2D hybrid kaolinite nanoclay system proves effective in reducing heat release and volatile leaching. Furthermore, the system facilitates the formation of reinforcing skeletons through a crosslinking mechanism during pyrolysis, resulting in the development of a compact char layer. This char layer acts as a protective barrier, enhancing the material’s resistance to heat and flames. In terms of mechanical properties, the multilayered polygonal flake-shaped 2D NKN plays a crucial role by impeding the formation of cracks that typically arise from vulnerable areas, such as adhesive phase particles. Simultaneously, the 1D HNT bridges these cracks within the matrix, ensuring the structural integrity of the composite material. In an optimal scenario, the homogeneously distributed 1D/2D hybrid kaolinite nanoclays exhibit remarkable results, with a 51.0% improvement in mode II fracture toughness (GIIC), indicating increased resistance to crack propagation. In addition, there is a 34.5% reduction in total heat release, signifying improved flame retardancy. This study represents a significant step forward in the field of composite materials. The innovative use of hybrid low-dimensional nanomaterials offers a promising avenue for the development of multifunctional composites. By carefully designing and incorporating these nanoclays, researchers can potentially create a new generation of FRP composites that excel in both flame resistance and mechanical strength.

Abstract The ecological benefits and concerns surrounding fossil fuels had led to increased interest in bio-based rigid polyurethane foam (RPUF). Nonetheless, due to its flammability, it had limited application in various fields. To solve this problem, a green bio-flame retardant, cobalt hydroxystannate (CoSn(OH)6), was prepared and compounded with montmorillonite (MMT) and chick feather protein (CF), and applied to RPUF, which not only realized the regeneration of resources, but also provided RPUF with better thermal stability, flame retardancy and smoke suppression properties. The experimental results showed that when 3 wt% CoSn(OH)6 was added, the RPUF (CF1/MMT3/Co3) had the greatest activation energy. In addition, the peak heat release rate (PHRR) and total heat release (THR) of CF1/MMT3/Co3 decreased by 12.73%, and 11.16% respectively, compared with no CoSn(OH)6. In addition, its Ds decreased by 28.9% and the light transmittance increased by 17.6% compared with the RPUF without CoSn(OH)6. At the same time, its peak smoke production rate (PSPR) and the total smoke release (TSR) decreased by 25% and 18%. And CF1/MMT3/Co3 also had the lowest fire risk evaluation index. This study presented possibilities for practical utilization of the RPUF substances founded on bio-based flame inhibitors.

Abstract This study aimed to improve the flame retardancy and mechanical properties of bacterial cellulose (BC) by introducing cereal proteins, namely zein and gluten. The production conditions were determined by observing residual masses of samples at 1000 ℃ using thermogravimetric analysis (TGA). According to the TGA results, the optimized production conditions for the BCs with zein and gluten were combined solvent exchange and entrapment of 20 weight% (wt.%) of zein, and entrapment of 40 wt.% of gluten, respectively. Surface characterization of BC prepared with zein and gluten under the optimal conditions confirmed that the cereal proteins were incorporated into the BC nanostructures via solvent exchange and/or entrapment and the original chemical and crystal structures of BC were not significantly changed. Limiting oxygen index (LOI) analysis confirmed that cereal proteins improved the flame retardancy of BC. In particular, the LOI of BC entrapped with gluten was 50%, which was better than that of cowhide leather. Char morphology analysis confirmed that the as-produced BCs with cereal proteins exhibited condensed-phase flame-retardant mechanism by forming intumescent chars. Analysis of the mechanical properties confirmed that compared with cowhide leather, as-produced BCs with cereal proteins possessed high tensile strength and dimensional stability, making them suitable leather substitutes.