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Wood, a flammable material, poses safety risks due to heat and smoke release during combustion and is a huge safety hazard. The current approach involves impregnating water-soluble inorganic flame retardants into wood. However, these retardants are susceptible to leaching, negatively impacting the aesthetic appearance and flame retardancy of wood. Herein, a liquid mix of ammonium dihydrogen phosphate, boric acid, and magnesium chloride was vacuum-pressure impregnated into wood. Subsequent concentration and drying produced composite salt particles (named as P–B–Mg). The wood was immersed in sodium silicate solutions of different concentrations. Mg2+ leached from P–B–Mg rapidly combined with SiO 3 2− to precipitate an MgSiO 3 layer on the particle surfaces. This in-situ synthesis resulted in P–B–Mg@MgSiO 3 hybrid flame retardant with core-shell structure within wood cells. The modified wood displayed superior performance, achieving non-combustible level in limiting oxygen index test and remaining self-extinguishing even after continuous exposure to open flame at 1100 °C for 205 s. Compared with that of untreated wood, the total heat release and total smoke production of the P–B–Mg@40%MgSiO 3 -modified wood decreased by 94.7 and 86.5 %, respectively. Residual char and pyrolysis analysis showed that the flame retarded process of modified wood involved gas, liquid and solid phase synergy effects. Meanwhile, the modified wood exhibited excellent resistance to leaching, durable flame retardancy, smoke suppression after 14-d water immersion cycles. Furthermore, it displayed good anti-degradation properties with pH value close to that of untreated wood. Thus, the modified wood possesses stable material properties suitable for long-term use in both indoor and outdoor applications. [Display omitted] • Core-shell structured hybrid flame retardant was in situ synthesized in wood. • THR and TSP decrease by 94.7 and 86.5 %, ensuring superior fire safety. • Achieves non-combustible level, resisting ignition at 1100 °C for 205 s. • Resistant to leaching, with 56.6 % mass retention after 14-d water immersion. • pH stability and anti-degradation performance ensure long-term use. [ABSTRACT FROM AUTHOR]

This study explores the formulation space of flame retardant thermoset polymers, specifically involving blends of epoxy and cyanate ester (EP/CE) and a reactive phosphorus-based flame retardant, poly (m -phenylene methylphosphonate) (PMP). Two CE monomers were investigated, each blended with the same epoxy monomer (DGEBA) in a 1:1 wt ratio. The impact of phosphorus concentration on the neat (neat meaning no fibers were present) resin blends was characterized using differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). The flammability and mechanical characteristics were assessed using micro-combustion calorimetry (MCC) and dynamic mechanical analysis (DMA). Carbon fiber composite panels were successfully fabricated using a wet layup process and autoclave curing with a fiber volume fraction (V f) of approximately 0.5. DMA testing of the cured composite laminates pinpointed that the average T g of the EP/CE blend was reduced with PMP addition by up to 39 °C at a phosphorous level of 3 wt%. Cone calorimetry tests confirmed the effectiveness of the flame retardant by reducing the peak Heat Release Rate (HRR) by approximately 27 %. The integration of PMP into EP/CE only marginally reduced the 3-point flexural strength (6–15 %) and modulus (7–13 %) relative to baseline samples. [ABSTRACT FROM AUTHOR]

Due to the high polarizability of traditional flame retardants, it is difficult to meet the excellent dielectric properties and flame retardancy required for electronic packaging materials. Therefore, we have designed a novel linear polyphosphazene that can balance the dielectric properties and flame retardancy of bismaleimide (BMI) composites. Here, fluorinated aromatic ring structure with the large freedom volume is connected to the main chain of polydichlorophosphazene (PDCP) as a side group, resulting in multifunctional fluorinated linear polyphosphazene (PBTFP). Attributed to the excellent P/N/F combination flame retardant strategy, extremely low polarizability, and large molecular free volume, PBTFP simultaneously improves the dielectric properties and flame retardancy of the BMI composites, including UL-94 rating of V0, and a dielectric constant (D k) as low as 2.69. In addition, as an elastomer, PBTFP exhibits positive effects on improving the hydrophobicity and toughness of BMI. Therefore, through a simple affinity substitution reaction, we prepared a multifunctional fluorinated linear polyphosphazene modified BMI based electronic packaging substrate material that can be applied to 5G high-frequency communication. [Display omitted] [ABSTRACT FROM AUTHOR]

The mechanical shock and thermal damage generally exist together in hazardous environment, whereas traditional single protective materials are difficult to achieve all-round protection under extreme environment. Herein, to realize the integration of multifunctional abilities about impact resistance, flame-retardant and sensing performance, a "solid-liquid host-guest" structural shear thickened composite sponge is proposed, which flame-retardant shear thickening fluids with an extraordinary thickening ratio of 2183.95 % continuously disperse in 3D sponge matrix. The resulting composite sponge effectively attenuates the impact force by nearly 80 % with the thickness of only 4 mm via a cooperation between the effect of shear hardening and structure densification. Meanwhile, after burning on the alcohol flame for 12 s, the composite sponge with 7 wt.% fire-retardant additive maintains a complete morphology and realizes self-extinguishing with a reliable flame-retardant ability. Attributed to the good electrical conductivity of shear thickening fluid, the composite sponge serves favorably in human body monitoring, impact sensing and fire warning. In a word, this multifunctional lightweight composite sponge is expected to realize the integration of early warning and protection, which is a competitive candidate material for the intelligent protection in complex environments. [Display omitted] • A new type of conductive shear thickening fluid was prepared. • The sensing performance endows P-STF sponge with human body monitoring function. • The P-STF sponge protects against both impact and thermal hazards. • The P-STF sponge achieves the integration of protection and early warning. [ABSTRACT FROM AUTHOR]

Fire hazards are a primary concern in aircraft accidents, and controlling combustible materials is pivotal in managing cabin fire risks. This work aims to elucidate the impact of widespread measures that introduce phosphorus-based flame retardants (PFRs) on the fire safety of carbon fiber epoxy composites (CF/EP). Firstly, the hazardous indicators for flame retardant CF/EP composites exhibit two categories of optimization and degradation, which are caused by the intrinsic feature, pyrolysis characteristics and chemical valence states of PFRs. Secondly, the fire hazards of composites are assessed by fusing the analytic network process and information weights guided by Nash Equilibrium theory. The method combines the merits of subjective and objective weights from dimensions of intrinsic hazards, interrelationships and data dispersion of indicators. Finally, the assessed fire hazard rankings under 35 and 65 kW/m2 both are EP > CF/EP16%DOPO-HQ > CF/EP > CF/EP7%DPO. In conclusion, DOPO-HQ (+1) primarily increases the fire hazard of CF/EP due to gas-phase flame-retardant effects, while DPO (+3) predominantly reduces the fire hazard of CF/EP by contributing to condensed-phase effects. This work highlights the contradictory effects of PFRs on the fire safety of CF/EP composites due to structure and thermal stability. The proposed ANP and IW hybridization method provides a theoretical foundation for selecting flame retardants and assessing material fire hazards comprehensively. [ABSTRACT FROM AUTHOR]

Fire safety and protection are very important but still show a critical global challenge. Developing smart fire warning materials with combined passive flame retardancy and active fire alarm response is promising for reducing or avoiding serious fire disasters. Various nano-fillers (e.g., graphene oxide and MXene) based composite coatings have proven to be effective for monitoring critical fire risk of various combustible materials; however, they still show some shortages, for example, high cost, black color, poor weather resistance and complicated fabricating process. Here, we report a green, cost-effective and large-scale strategy for fabricating water-based 3D-titania/2D-montmorillonite/1D-celluose nanofiber (TiO 2 /MMT/CNF) hierarchical nanocomposite coatings with adjustable color, mechanical robustness, good flame retardancy, long-term weather resistance and sensitive fire cyclic alarming response. The formation of strong chemical bonding and hydrogen bonding interactions among polyethylene glycol molecules and multi-scale nano-fillers together with silane surface modification can produce good mechanical flexibility (folded crane), surface hydrophobicity (water contact angle of 152°) and exceptional flame resistance (good structure integrity after 120 s flame exposure). Notably, the optimized nanocomposite coatings exhibit ultrafast fire alarm response (<3.5 s) and stable fire cyclic alarming capability via the possible band transition of the TiO 2 network under flame. Further, such color-adjustable nanocomposite coatings can be easily fabricated for large-scale production, and they show excellent stable flame retardancy and stable fire cyclic warning response even after more than one-year outdoor exposure. This work provides a promising and green fire-warning nanocomposite coatings with combined passive-active functionalities for fire warning and protection. • Water-based nanocomposite coatings are fabricated by a facile and green approach. • Hierarchical TiO 2 /MMT/CNF interconnected networks are constructed and optimized. • The hybrid coatings exhibit good flame resistance and sensitive fire cyclic warning. • Color adjustable, weather resistant and stable outdoor fire warning are demonstrated. [ABSTRACT FROM AUTHOR]

Effective rope rescue is crucial for evacuating individuals trapped in high-rise fires and for ensuring their safety in extreme fire environments. However, conventional fire rescue ropes often prioritize mechanical properties and flame retardancy, neglecting the crucial aspects of escape monitoring and position acquisition. Herein, we present a facile strategy to fabricate flame-retardant braided electronic rope (FBER) with a core-shell structure by large-scale braiding techniques. The pressure-sensing performance of the FBER was optimized by altering the braiding structure, which relies on the cross-contact between the core-braided composite yarns (CBCYs) at the sensing point. The unique structural design of FBER effectively prevents thermal transfer, ensuring pressure-sensing stability in extreme environments. Our results demonstrate that the FBER exhibits high sensitivity, rapid response, and excellent durability over 3500 cycles at 200 °C. The optimized FBER can be integrated into fire rescue detection systems for real-time escape monitoring, position acquisition, and safety detection during fire rescue operations. The scalable and multifunctional design of the FBER can significantly aid the development of fire rescue ropes. [ABSTRACT FROM AUTHOR]

Impact injuries and fire risks generally coexist simultaneously in extreme environments. In this context, it is of great necessity to design impact resistant materials with both flame retardant performance and thermal stability. Here, a multi-functional flame retardant coating was prepared from the combination of silica sol (Si-sol), phytic acid (PA) and expandable graphite (EG) by graft modification with γ-propyl-trimethoxysilane (KH550). Subsequently, hierarchical composites were fabricated using one-pot foaming and brush coating method, where the carbon fiber cloth and coating served as the surface layer, while rigid polyurethane foams (RPUF) acted as the interlayer. The hierarchical structure endowed the RPUF composites with high compression resistance and impact resistance properties. Furthermore, the flame retardant coating could effectively reduce the values of peak heat release rate and peak smoke production rate of RPUF composites by 77.5% and 81.8%, respectively. Therefore, these RPUF composites can effectively prevent impact damage and achieve excellent flame retardancy, making them promising candidates as safety protective materials. [Display omitted] [ABSTRACT FROM AUTHOR]

The understanding of the damage mechanisms for woven laminate plates under low-velocity impact is challenging as the damage mechanisms at the interface of adjacent layers are dominated by the fibre architecture. This work presents an experimental investigation of the behaviour of woven glass and carbon fibre composite laminates in a matrix of fire retardant resin under low-velocity impact. The performance is evaluated in terms of damage mechanisms and force time history curves. Six impact energy levels were used to test standard plates to identify the type of damage observed at various energy levels. Scanning electron microscopy (SEM) along with C-scans were used to characterise the damage. It has been observed that in woven composites, the damage occurs mostly between the fibre bundles and matrix. As the impact energy increases, the failure involves extended matrix cracking and fibre fracture. Moreover, due to the fibre architecture, both the contact forces between bundles of fibres and stretching of the bundles are responsible for the dominant matrix cracking damage mode observed at the low-impact energy level. As the impact energy increases, the damage also increases resulting in fibre fracture. The experimental evidence collected during this investigation shows that for both the carbon fibre and the glass fibre woven laminates the low-velocity impact behaviour is characterised by extended fibre fracture without a noticeable sudden load drop. [ABSTRACT FROM AUTHOR]

Rare earth elements, the collection for 17 chemical elements in the third main group B on the periodic table of chemical elements, have received intensive attention in recent years. Based on the special electronic structure and physiochemical properties, rare earth elements are used as efficient flame retardants for polymers. Nowadays, various methods have been used for the synthesis of rare earth-based flame retardants, including precipitation, in situ polymerization and self-assembly methods. To date, zero-dimensional (0D), one-dimensional (1D), two-dimensional (2D) and three-dimensional (3D) rare earth-based flame retardants have been developed to impart excellent fire safety to versatile polymeric materials, e.g. polyester, epoxy resin, polyurethane and polyolefin. The processing methods and flame retardancy of rare earth-based flame retardant/polymer composites are summarized. Subsequently, the flame-retardant mechanism of rare earth-based flame retardants in polymers is reviewed. Finally, the challenges and development prospects of rare earth-based flame retardant/polymer composites are discussed. [ABSTRACT FROM AUTHOR]

A phosphorous-silicon (SiP) precursor was synthesized using p-phthalaldehyde, (3-aminopropyl) triethoxysilane and 9,10-dihydro-9-oxa-10-phosphaphenantrene-10-oxide. The SiP was used to fabricate a phosphorous-silicon hybrid microsphere (SiP-M) via the sol-gel method. The SiP-M was employed to enhance the flame retardancy of poly (butylene adipate-co-terephthalate) (PBAT). The results indicate that PBAT containing 0.1 wt% of SiP-M displays a UL-94 V0 rating and a limiting oxygen index (LOI) value of 26.5 vol%. Meanwhile, PBAT containing 1.0 wt% SiP-M exhibits a UL-94 V0 rating and a LOI value of 29.8 vol%, and some reductions in peak heat release rate, total heat release, and total smoke production. The SiP-M functions in both the gas phase and condense phase in the PBAT blend, and the former is predominant. In addition, a coupling agent KH560 was used to modify the interface adhesion between PBAT and SiP-M. The tensile strength and elongation at the break of PBAT blends are enhanced by an appropriate amount of KH560. This work provides an efficient method for preparing flame-retardant PBAT without deteriorating its mechanical properties. Poly (butylene adipate-co-terephthalate) with 0.1 wt% P/Si hybrid microsphere displays a UL-94 V0 rating. [Display omitted] • A phosphorous-silicon microsphere SiP-M was used in poly (butylene adipate-co-terephthalate) (PBAT). • A small amount of 0.1 wt% SiP-M endows PBAT with a UL-94 V0 rating. • SiP-M works mainly in the gas phase during combustion. • A coupling agent regulates the mechanical properties of PBAT/SiP-M blends. [ABSTRACT FROM AUTHOR]

Interest in advanced multifunctional composite materials has generated extensive discussions on materials endowed with high fire-resistance, mechanical strength, and excellent electromagnetic interference (EMI) shielding. We designed a feasible and low-cost method for preparing mechanically robust thermoplastic polyurethane/triazine-rich polyphosphazene functionalized titanium carbide@copper phytate/carbon fiber fabric (TPU/PZM@CP/CF) nanocomposites with enhanced fire retardancy and EMI shielding performances. The as-prepared TPU/PZM@CP-2.0/CF demonstrated excellent mechanical toughness, with a tensile strength of 57.8 MPa. Additionally, this nanocomposite exhibited superior EMI shielding performances, with an EMI shielding effectiveness of 29.7 dB and a normal shielding effectiveness of 24.8 dB/mm, surpassing that of most other TPU-based nanocomposites. Furthermore, the thermal stability and fire resistance of the TPU/PZM@CP nanocomposites were significantly improved. For instance, the peak of heat release rate and the peak of smoke production rate of the TPU/PZM@CP-2.0 respectively decreased by 41.5% and 21.5%, compared to those of neat TPU. In this work, the simple preparation method and outstanding comprehensive performances of the mechanically strong multifunctional TPU/PZM@CP/CF have tremendous potential for applications in defense, smart electronic device and aerospace. [Display omitted] • High-performance multifunctional hierarchical nanosystem are prepared. • Nanocomposites has high fire safety, mechanical robustness and EMI shielding. • Properties of hierarchical nanocomposite are superior to those previously reported. • Hydrogen bond, charring and continuous network lead to properties improvement. [ABSTRACT FROM AUTHOR]

The intumescence, compactness, and strength of char are the key points to the intumescent flame retardant system. However, the char residues of flame retardant polymers rarely exhibit all three characteristics, especially strength. Herein, a novel Cu2+-doped intumescent flame retardant (Cu–CHP) was prepared without producing any waste. When Cu–CHP was exposed at a high temperature (∼1400 °C), it can rapidly expand and carbonize to form dense char. Surprisingly, the intumescent char residue of Cu–CHP can hold up more than 2000 times its own weight. Benefitting from the excellent intumescent charring capacity of Cu–CHP, the resultant EP/Cu–CHP 18% composite can withstand around 600 s penetrating of butane flame (∼1400 °C) because of strong dense char protection, and only 0.9 wt% Cu2+ content resulted in the limiting oxygen index (LOI) of EP/Cu–CHP 18% increases to 31% and the vertical burning (UL-94) reaches V-0 rating. Additionally, its peak heat release rate, total smoke production, and fire growth rate are significantly reduced by 70%, 53%, and 75%, respectively, compared with neat epoxy resin. Especially, the smoke density of EP/Cu–CHP 18% was dramatically dropped by more than 68%. Because a Cu2+-doped intumescent, compact, and strong char residue was produced during burning. This work provides a new strategy to impart excellent flame retardancy and smoke suppression to highly flammable polymers by building metal-doped strong intumescent char residues. [Display omitted] • Cu2+-doped flame retardant was prepared without producing any wastes. • Cu2+-doped intumescent, compact, and strong char residue was produced. • Excellent flame retardancy and smoke suppression were imparted to epoxy resin. • The intumescent flame retardant mechanism was proposed. [ABSTRACT FROM AUTHOR]

Firefighting protective clothing is an essential equipment for firefighters that can provide protection from all kinds of thermal hazards and prevent burn injuries. However, it is still a challenge to develop lightweight firefighting clothing without compromising their excellent fire-resistant and thermal-protective performance. In this study, we report a novel polyimide aerogel fiber-based double-layer smart textile comprising of flame-retardant outer layer (ambient-side) with excellent fire resistance and phase-changeable inner layer (next to skin side) with thermal-regulating function, achieving comprehensive flame-retardant and thermal-protective function. The polyimide-hydroxyapatite-reduced graphene oxide (PI-HAP-rGO) aerogel fabric (outer layer) acquires 54.7% and 70.0% reduction of peak heat release rate compared with that of pure PI aerogel fabric and commercial aramid fabric, respectively, exhibiting excellent fire resistance. The phase-changeable polyimide-hydroxyapatite/eicosane (PI-HAP/C20) fabric (inner layer) with high melting enthalpy of 193.2 J g−1 can delay the temperature rise by thermal buffering effects during the phase change process, endowing cool somatosensory temperature for firefighters. Consequently, the double-layer smart textile can extend the time (280.0 s) to pain threshold of human skin, much longer than that of the commercial aramid fabric (101.0 s) and glass fiber fabric (56.5 s), which exhibits huge potential for next-generation firefighting clothing. A novel polyimide aerogel fiber-based double-layer smart textile comprising of flame-retardant outer layer and phase-changeable inner layer exhibited outstanding flame-retardant and thermal-protective performance, demonstrating great potential for next-generation firefighting clothing. [Display omitted] • The smart textile comprising of PI-HAP-rGO aerogel fabric as the outer layer and PI-HAP/C20 fabric as the inner layer was fabricated. • PI-HAP-rGO aerogel fabric exhibits efficient fire resistance with the limited oxygen index value (LOI) up to 47.5%. • There exists 70.0% reduction of PHRR for PI-HAP-rGO aerogel fabric compared with that of commercial aramid fabric. • PI-HAP/C20 fabric has excellent thermal management with high melting enthalpy (193.2 J g−1). • The smart textile could delay around 280.0 s to reach pain threshold in the high temperature environment. [ABSTRACT FROM AUTHOR]

Lightweight, mechanically flexible and flame retardant polydimethylsiloxane (PDMS) foam materials modified with low content of nano-fillers are highly needed for versatile applications. Instead of the direct mechanical mixing technique that induced the embedment of nanofillers inside the matrix, herein, a facile, rapid and green restricted assembly strategy was established to prepare PDMS foam composites coated with an extremely low content of restricted graphene oxide (GO) sheets. A GO/water mixture in silicone oil emulsion was prepared to produce the restricted assembly of GO layers precisely and solely on the foam surface with no GO sheets inside the skeleton. Based on such restricted assembly induced by the amphiphilic surfactant molecules, the presence of only ∼0.04 wt% GO greatly improved the flame resistance (e.g., 40.6% reduction in heat release rate and 27.1% of limit oxygen index) of PDMS foams without affecting the low density (∼0.23 g/cm3) and mechanical flexibility (unchanged stress at strain 70% after 100 cycles under 200 °C). Observations and analysis of the burnt zones demonstrated that the restricted ultralow content GO sheets formed a compact protective layer facilitated by the pyrolysis of the PDMS molecules, thus protecting the inside of the PDMS material from the heat and oxygen attacks. These results confirmed that the restricted self-assembly of 2D nano-fillers approach is effective for the fabrication of flame-retardant PDMS foams and retention of other important properties. [ABSTRACT FROM AUTHOR]

Devoting to coping with safety risk spreading with polymers, this work achieves dramatic synergistic improvements in composite toughness, photothermal healing, and fire safety through a novel targeted modification strategy for black phosphorus (BP). In detail, we herein use the emerging 2D BP as a template for in-situ growth by covalent triazine framework (HBP-CTF). Incorporating gradient increased HBP-CTF (1, 2, 4 wt%) into polystyrene (PS), the elongation at break increased by 61.59%, 74.60% and 62.82% for composites, respectively. This is attributed to the synergistic effects of two components of HBP-CTF as stress conduction unit and interface and dispersion improver, respectively. Furthermore, PS/HBP-CTF composites achieve photothermal healing over 96% in strength and elongation at break induced by outstanding photothermal properties (linearly quantifiable, R2 > 0.997). Noted, PS/HBP-CTF 2.0 and PS/HBP-CTF 4.0 achieve record reductions of 61.77% and 69.85% in peak heat release rate, accompanied by dramatically reduced total heat release. Taking the pyrolysis of HBP-CTF as an index, this work proposes the idea of using P 4 as the key product to monitor and distribute gas phase effects for BP-based flame retardants. The hybridization of CTF to HBP promotes the slow and continuous release of P 4 in the gas phase, revealing the structure and composition of char that cross-linking P and N. This work provides strategies for synergistically overcoming composite brittleness, crack failure, and high flammability, paving the way for practical applications. [ABSTRACT FROM AUTHOR]

The design of high transparent epoxy resins (EPs) with excellent flame retardancy and mechanical strength is still intractable, while the current use of phosphorus-based flame retardant usually destroys the transparency and color of EPs. This work reports a phosphorus-free hyperbranched polyborate (HBPB) as a multifunctional flame retardant additive for EPs. The HBPB was synthesized via a facile, one-pot, solvent- and catalyst-free polycondensation with branched aliphatic backbone and borate group, which features good compatibility within resin matrix and does not affect its curing processability. Compared to neat EP, the as-constructed EP composite with 9% addition of HBPB displays the high fire resistance (30.2% LOI value and UL-94 V0 rating), and the fire hazards such as smoke, heat and toxic gases release are significantly reduced without introducing phosphorus group. Surprisingly, the EP material can well maintain its high transparency and color with ultra-high toughness (21.38–40.50 kJ m−2) and flexural strength (137.03–197.08 MPa) achieved, especially the glass-transition temperature can be improved from 150 °C to 170 °C, making it superior to previously described counterparts. Highlighting the compelling results, this work provides a promising candidate on seeking the halogen-free solutions to alleviate the high price of phosphorus-based FRs, and paves a useful strategy toward designing high transparent, high-performance polymeric materials. [Display omitted] • A novel phosphorus-free hyperbranched polyborate FR was proposed to EPs. • HBPB shows good compatibility and do not affect the curing processability of EP. • The EP composite with superior toughness, fire-retardancy and high Tg was obtained. • EP material can well maintain its transparency with improved overall performance. • A full-scale study was conducted to clear the mechanism of this novel boron-FR. [ABSTRACT FROM AUTHOR]

Aiming to address the problems of flammability and brittleness of BMI and reduce the use of petroleum-based materials, three kinds of cardanol-based co-curing agents (CDPO, CDPC, CDCP) were synthesized and applied to prepare advanced BMI. Compared to the neat BMI, the modified BMI exhibited better thermal stability with higher decomposition temperatures and char yields. The BMI/CDCP-10 containing 4.5 wt% CDCP possessed the best flame retardancy with 50.4% reduction in PHRR, 27.5% reduction in THR and 21.2% reduction in TSP compared to those of neat BMI. Moreover, with the 4.5 wt% incorporation of CDPO, CDPC and CDCP, the impact strength of BMI was enhanced by 95%, 133.8% and 127.5% respectively, due to the flexible fatty chains and the decreased crosslinking density. The reason for different modification effects among modified BMI systems is studied from the structure of modifiers, finding that the phosphorylated cardanol with higher content of O and higher valence of P can be utilized to improve the mechanical property and fire safety of BMI. This work provides a new way to reduce the dependence on the petroleum-based materials and expand the application areas of BMI. [Display omitted] • Three cardanol-based co-curing agents (CDPO, CDPC, CDCP) with different phosphorous structure were synthesized. • The PHRR, THR and TSP of BMI with 4.5 wt% CDCP can be declined by 50.4%, 27.5% and 21.2%, respectively. • The impact strength of BMI was maximally increased by 133.8% with the 4.5 wt% CDPC. • The thermal stability, flame retardancy and mechanical performance of BMI were greatly elevated by the modifiers. [ABSTRACT FROM AUTHOR]

A large amount of cellulose is produced by photosynthesis every year, and cellulose products are widely used in daily life. However, flammability and easy to breed bacteria of cellulose has hidden risk of fire and public health during using, and the materials that can endow cellulose with flame retardancy and antibacterial properties is still lacking. Herein, novel hybrid nanoparticle (SiDP) based on inorganic nano SiO 2 , Schiff base and quaternary ammonium salt was developed to synchronize these two properties. Wherein the thermal stability of nano SiO 2 and the cross-linking structure of Schiff base played as synergistic flame retardant for the nanoparticle while quaternary ammonium salt of N, N′-dimethyl-N-(3-(trimethoxy silyl) propyl) octadecan-1-aminium chloride (DMOAC) was introduced to provide antibacterial property. The results demonstrated that the modified cotton fabrics were significantly out-performing of flame retardancy and antibacterial properties. Wherein LOI increased to 27.6%, the peak of heat release rate (pHRR) reduced by 34.2%, and capability of self-extinguishing was achieved. The antibacterial of SiDP and modified cotton fabrics were substantiated up to 99.9% against the Staphylococcus aureus and Escherichia coli. More excitingly, low toxicity of SiDP was confirmed via MTS assay by L929 fibroblast cells. The anti-infection in-vivo model was constructed and confirmed SiDP had a positive prevention of infection based on the wound healing rate of 91.1% after 14 days' treatment. The flame retardancy, antibacterial and biocompatibility of SiDP indicated it was an ideal candidate of nanomaterials in cellulose modification. [Display omitted] [ABSTRACT FROM AUTHOR]

With the development of highly integrated and miniaturized electronic devices, silicone rubber composites with good mechanical flexibility, high thermal conductivity and excellent flame resistance have aroused considerable interest in both industrial and research community. However, the effect of different geometries of thermally conductive fillers on the processing, mechanical and thermal properties as well as flame resistance of silicone rubber composites is still not clear. Herein, liquid silicone rubber (LSR) composites filled with three geometries of thermal conductive fillers i.e. spherical-like aluminum oxide (Al 2 O 3), irregular aluminum nitride (AlN) and 2D boron nitride (BN) sheets were prepared by an extremely simple mechanical-mixing process. As expected, incorporation of BN sheets into LSR matrix produces much higher increase in the viscosity, tensile strength and hardness than the corresponding AlN and Al 2 O 3 fillers, respectively. Typically, at a fixed filler loading of 120 phr, the increased thermal conductivity and heating/cooling efficiency of the BN/LSR composites display much better than the corresponding AlN/LSR and Al 2 O 3 /LSR composites, e.g. 316, 124 and 88% improvement in thermal conductivity, respectively. Interestingly, the thermal stability and flame resistance of the three composites present unexpected different phenomena. Compared with the pure LSR, the addition of AlN and Al 2 O 3 exacerbates the thermal degradation of LSR chains, while the presence of BN sheets improves the flame resistance of LSR dramatically, which is attributed to the compact BN/silica residue after burning that effectively restricts the heat and oxygen to attack the inside LSR chains. [ABSTRACT FROM AUTHOR]

As one of the lightest materials in the world, aerogels are widely adapted in heat insulation, electromagnetic interference shielding, oil-water separation, etc. Nevertheless, owing to their high flammability, the application scenarios of aerogels in extreme environments are severely limited. To reduce the intrinsic inflammable properties of aerogels, nanomaterials are commonly incorporated as additives to fabricate flame retardant nanocomposites, which creates a barrier effect and catalytic carbonization capacity. Nonetheless, up-to-date, the multifunctional development of these aerogels has been barely explored. Herein, we systematically summarized the recent progress on multifunctional nanocomposite aerogels based on various nanomaterials with different dimensions. The preparation approaches and performance evaluation of the most common types of aerogels were depicted in detail. Moreover, the investigation of multifunctional aerogels and their prospects were demonstrated, and in-depth discussed. This review work aims to deliver an insight towards further directions and developments of multi-functional flame-retardant aerogels for extended applications in extreme environments. [Display omitted] • The recent progress on flame retardant nanocomposite aerogels was reviewed. • The preparation approaches of the nanocomposite aerogels were described. • The proprieties and application of the flame retardant aerogels were illustrated. • The prospects of the flame retardant nanocomposite aerogels were depicted. [ABSTRACT FROM AUTHOR]

As a graphene-like material, MXene, represented by Ti 3 C 2 T x , has been found to possess promising flame retardant potential in polymers due to their excellent thermal and catalytic actions, as well as lamellar barrier effect. Thus, it is of great significance to explore whether MXene with double transition metal components has a higher flame retardant efficiency. Herein, Ti 3 C 2 T x and bimetallic MXene (Mo 2 Ti 2 C 3 T x) were fabricated by acid-etching method and then introduced into epoxy resin (EP) for the comparative investigation of their flame-retardant effect. The results indicated that MXenes were homogeneously dispersed in EP matrix, which can contribute to the improvements of thermal and flame retardant properties of EP composites. Upon the incorporation of 1 wt% Mo 2 Ti 2 C 3 T x MXene, the EP composites achieved a significantly reduced maximum mass loss rate (R max) by 39.4%, superb over EP/Ti 3 C 2 T x composites. Moreover, Mo 2 Ti 2 C 3 T x MXene endowed EP composites with a notable downward trend in fire risk, reflected by the decreasing PHRR of 34%, PSPR of 32.7%, TSP of 57.7%, PCO of 30.8%, along with significantly reduced SF value by 72.7%, which was superior to EP/Ti 3 C 2 T x composites. The strong catalytic attenuation and charring effect of transition metal Mo–Ti elements for bimetallic Mo 2 Ti 2 C 3 T x MXene, as well as nanosheet structure, imparted excellent fire retardant performance to EP composites. This work provides new insights into the application of bimetallic MXenes in flame retardant polymer composites. [ABSTRACT FROM AUTHOR]

With the advent of the 5G era, preparing conductive polymers to accomplish electromagnetic interference (EMI) shielding, mechanical enhancement, and flame retardancy are of vital importance. Graphite felt (GF) acts as a three-dimensional structure and organophosphorus derivatives containing different valences work as a flame retardant to form a novel EP composite. With GF incorporated into EP, EMI shielding effectiveness (SE) achieves around 60 dB, and absorption is dominated in the X band (8.2–12.4 GHz). Meanwhile, GF could exert a fiber reinforcement effect to enhance the mechanical properties of EP composites, tensile strength and impact strength of EP/GF are increased by 19.1% and 64.2%, respectively. However, owing to the "wick effect" of GF, 20 wt% DOPO-PEPA is added to acquire flame-retardant EP composites. Herein, a potential strategy broadens applications of EP composites in the high-end field and is provided to prepare polymer composites. [Display omitted] • A cost-reasonable EP composites composed of 3D GF and two-valence phosphorous derivatives is successfully fabricated. • The EMI SE EP composites achieve around 60 dB in the X band. • The pHRR and THR of EP/GF/20FR are reduced by 53.4% and 35.3%, respectively. • EP composites exhibit potential promise for large-scale production and industrial applications. [ABSTRACT FROM AUTHOR]

As a biodegradable polymeric material, the polylactic acid (PLA) has broad applications resulting from its various advantages and unique characteristics. Nevertheless, the application of PLA in various fields is greatly limited by its high flammability. Our recent effort focuses on the manipulation of benzyldimethylhexadecylammonium chloride (HDBAC) modified titanium carbide (Ti 3 C 2 T x) ultra-thin nanosheets which are then used to improve the fire safety of PLA composites filled with silicon microencapsulated ammonium polyphosphate (SiAPP). The flame retardant evaluation showed that when 2.0 wt% HDBAC modified Ti 3 C 2 T x (HDBAC-Ti 3 C 2 T x) and 13.0 wt% SiAPP were added, the LOI value was increased to 33.3%, and the UL-94 V-0 level was obtained, besides the peak heat release rate, total heat release, peak smoke production rate and total smoke release decreased by 49.8%, 31.9%, 60.3% and 52.7%, respectively. The barrier and catalytic effects of the modified Ti 3 C 2 T x nanosheets together with the subsequently formed TiO 2 and phosphorus-containing species forming intact expanded carbon layers and interrupting the combustion route are responsible for remarkably improving flame retardancy and suppressing toxic gases of PLA. This work provides a new approach for greatly reducing the fire hazard of PLA. [Display omitted] [ABSTRACT FROM AUTHOR]

Fiber reinforced polymeric composites (FRPCs) have been widely used in automotive, aircraft, airspace, marine and civil construction. However, they are flammable, thus seriously threating the safety of human beings and property. To enhance the flame retardancy of FRPCs, suitable flame-retardant treatments have been carried out, which is efficiency in enhancing the thermal stability and fire resistance. In this review, the thermal decomposition characteristic of FRPC is initially introduced to understand the necessity of flame retardnacy. Then, the flame-retardant requirements of FRPC in different applications are summarized to guide the selection of flame retardant and flame-retardant method. The main section concentrates on the flame-retardant method and mechanism as well as research status in flame retardation for FRPC. The flame-retardant methods to treat fiber, polymer and composites are discussed, and the advantages and limitations of each method are also introduced. Finally, a brief outlook at the development of the flame retardation for FRPC is summarized. [ABSTRACT FROM AUTHOR]

Presented here is an investigation into the cure kinetics, thermal and mechanical properties, and fire resistance of a carbon fibre composite using a polymer matrix blend composed of 1,3 phenylene bisoxazoline, a phenolic resin and dodecylbenzene sulfonic acid. This polymer matrix is further modified with a benzoxazine, a tetra-functional epoxy amine resin and the engineering thermoplastic, polyether sulfone (PES) to explore their effect on the reaction mechanism and final properties of the composite after cure and post-cure. The modifiers reduce the reactivity of polymerisation and the final glass transition temperature of the network as shown by the rate constants, determined from the Kissinger and Sestak–Berggren models. Subsequent post-curing of the composite increases the glass transition temperature, thermal stability, interlaminar shear strength, and fire performance as determined by UL-94 vertical burn test. Ensuring the network is fully cured is clearly critical to optimum performance of the composite. The high char yields of the bisoxazoline polymer networks, particularly after post-cure illustrate great potential for applications where high temperature resistance is required. [ABSTRACT FROM AUTHOR]

Nowadays, the underlying mechanism for the flame-retardant property derived from the metal-catalyzed pyrolysis of polyphosphazene composites is unclear, thus limiting the efficient utilization and further development of this high-performance catalytic-type flame retardants. Herein, polyphosphazenes terminated with amino (denoted as PNF) and hydroxyl (denoted as PZF) groups are coated on the surface halloysite nanotubes (HNT), thus affording HNT@PNF and HNT@PZF core-shell structures, respectively. Cu nanoparticles (2.6 ± 0.8 nm) are anchored on the surface of these two core-shell structures to generate flame retardants named as HNT@PZF-Cu and HNT@PNF–Cu. Cu nanoparticles show high catalytic thermal rearrangement of polyphosphazene for HNT@PZF-Cu instead of HNT@PNF–Cu, which is attributed to the interaction between Cu and HNT@PZF and a large specific surface area of HNT@PZF (93.5 m2/g). Compared with HNT@PNF–Cu, HNT@PZF-Cu exhibits better smoke suppression and flame retardancy for epoxy resin (EP). With 3 wt% loading of HNT@PZF-Cu, the peak heat release rate, smoke production rate, and carbon monoxide production of the EP nanocomposite are reduced by 52.2%, 40.3% and 64.2%, respectively. This is because polyaromatic compounds generated during the pyrolysis of HNT@PZF-Cu promote the rapid carbonization of EP nanocomposites, resulting in the formation of structural stable char residue. Meanwhile, Cu nanoparticles can effectively reduce the release of toxic fumes and the volatilization of volatile organic compounds (VOCs) during the catalytic combustion process. Density functional theory (DFT) calculation reveals that Cu nanoparticles catalyze the purification of toxic gases such as CO and NO. [Display omitted] • Two novel catalytic-type flame retardants (HNT@PZF-Cu and HNT@PNF–Cu) were incorporated to EP to decrease its fire hazards. • Cu nanoparticles loaded on HNT@PZF-Cu instead of HNT@PNF–Cu show high catalytic thermal rearrangement of polyphosphazne. • HNT@PZF-Cu promotes the rapid carbonization of EP nanocomposites and the formation of stable char. • Cu nanoparticles loaded on the HNT-based carriers catalyze the carbonization and purify the toxic gases. • Density functional theory (DFT) calculation reveals that Cu nanoparticles catalyze the conversion of CO and NO. [ABSTRACT FROM AUTHOR]

Mitigating the fire hazards of epoxy resin (EP) and simultaneously improving mechanical properties have always been a goal pursued by polymeric scientists. Herein, we prepared a lithium-containing hepta-isobutyl-POSS (ibu-T 7 -Li-POSS). The chemical structure of ibu-T 7 -Li-POSS was well characterized. Just via tuning the ethanol solution concentration, we can obtain zero-dimensional (0D) spherical nanoparticles, two-dimensional (2D) ultrathin mono-layer nanoflakes, three-dimensional (3D) multiple-layered lamellae and hexagonal petal-shaped micron-size crystal based on ibu-T 7 -Li-POSS. Regular macroscopic octahedron single crystal of ibu-T 7 -Li-POSS was analisized by single crystal X-ray diffraction. The prepared ibu-T 7 -Li-POSS was incorporated into EP to improve the mechanical properties and enhance the fire safety. When the ibu-T 7 -Li-POSS content was 1 wt%, the flexural strength of EP-1 was enhanced from 81.8 MPa of EP to 110 MPa. The incorporation of ibu-T 7 -Li-POSS can apparently decrease the dielectric constant and loss of EP nanocomposites. Moreover, when 5 wt% of ibu-T 7 -Li-POSS was incorporated into EP, the reduction of peak of heat release rate (p-HRR), peak of smoke production rate (p-SPR) and peak of CO production rate (p-COP) reached to 34.1%, 38.6% and 40.6%, respectively. Therefore, our findings provide a considerable promotion for the facile preparation of low-dimensional environment-friendly nano-/micron-flame retardants based on metal-containing polyhedral oligomeric silsesquioxane (M-POSS) compounds. [Display omitted] • A novel metal-POSS (ibu-T 7 -Li-POSS) is firstly synthesized via one-pot method. • Controllable dimensional ibu-T 7 -Li-POSS nano-/micron-crystals are fabricated. • Thermal stability and mechanical properties of EP nanocomposites are improved by introducing ibu-T 7 -Li-POSS. • Ibu-T 7 -Li-POSS apparently reduces fire hazards of the formed EP nanocomposites. • The mechanism of catalytic charring of lithium for EP is illustrated in detail. [ABSTRACT FROM AUTHOR]

Scientific researches have been focused on finding halogen-free solutions as effective as halogenated ones owing to environmental and health problems in recent years. This fact is the main driving force for upcoming academic works in the flame retardancy field. Boron compounds, are high potential flame retardant additive in polymer based materials owing to their low toxicity, molecular diversity, and various ways of flame retardant action. They have been used solely or as an adjuvant in combination with mineral fillers, intumescent systems, phosphorus, halogen, nitrogen, silicone and carbon containing additives. This review provides a comprehensive description of the flame retardant effect of boron compounds with general flame retardant mechanisms in natural polymers, biocomposite applications, thermoplastics, elastomers, and thermosets as well as the synergistic effect studies with other flame retardant additives. This review covers the related studies until the end of 2020. Remarkable future research opportunities and some challenges are also suggested. [Display omitted] [ABSTRACT FROM AUTHOR]

Plastic combustion has adverse impacts on air quality and human health. In this work, a novel non-aromatic Si, P, N-containing hyperbranched flame retardant (HPNSi) was synthesized and proposed to epoxy resin. The modified epoxy exhibits not only reduced fire hazards and less smoke production in favor of eco-friendly, but also remarkable mechanical properties and lower curing temperature for facile processability. With 6 wt% incorporation, the peak heat release and total smoke production were reduced by 29.6% and 20.7%, respectively, and the time to ignition (TTI) increased as well as the fire growth rate (FIGRA) dropped off, which is of vital significance for saving lives in a fire. Meanwhile, the impact strength and flexural strength greatly enhanced by 72.9% and 22.0%, while its curing temperature was lower than that of controlled EP system. Interestingly, we also found that the solid carbon particles on the char surface apparently reduced from SEM image. The blending of its unique non-aromatic hyperbranched structure containing Si, P, N with epoxy architecture was responsible for the desirable integrated enhancement. The broad possibilities in the field of flame-retardant plastic with reduced fire hazards and excellent integrated performance enable the novel hyperbranched flame retardant a bright future for application. [Display omitted] • Non-aromatic Si, P, N-hyperbranched FR was synthesized by facile polycondensation. • Significantly enhanced flame retardancy and low smoke release were achieved. • The HPNSi/EP exhibits outstanding mechanical properties and rapid curing rate. • Phosphorus group introduce to hyperbranched architecture led to great enhancement. • SEM show that HPNSi may inhibit carbon particle release on the char surface. [ABSTRACT FROM AUTHOR]

A self-healing coating containing polyethyleneimine (PEI)/ammonium polyphosphate (APP) polyelectrolyte complex was successfully prepared, and then was deposited on flexible polyurethane foam (FPUF) in association with graphene oxide (GO) via a simple dip-nip process to improve the flame retardancy and mechanical property. The vertical burning test revealed that the FPUF coated with PEI/APP and GO extinguished immediately after removing the igniter. The cone calorimeter results demonstrated that the coating effectively reduced the peak heat release rate by 63.8%. The char analysis suggested that PEI/APP formed an intumescent char structure and released inert gases, whilst GO improved the compactness of the char layer. Furthermore, the compressive strength of the coated foam sample was increased by 175.0% compared to that of the control FPUF sample. The mechanical properties analysis and morphology observation proved that the PEI/APP-GO coating had self-healing ability. This unique intrinsic self-healing coating provides a new opportunity for imparting flame retardancy and excellent mechanical property to foam materials used in many commercial cases. [Display omitted] • PEI/APP-rGO was coated on the foam via a dip-nip process. • The coating improved the flame retardancy and eliminated the melt dripping. • The coating significantly increased the mechanical properties. • The coating showed excellent durability and self-healing ability. [ABSTRACT FROM AUTHOR]

Polyurethane (PU) sponge has a wide range of applications in our daily life. Unfortunately, the PU sponge is highly flammable and becomes a breeding ground for bacteria, thereby threatening human health and life. To date, it remains a challenge to improve the flame retardant and antibacterial properties of PU sponge simultaneously without destroying its inherent elasticity and flexibility. Here we report a novel composite coating on the PU sponge using bioderived phytic acid and sodium lignosulfonate via a facile soaking method. Compared to the pristine sponge, the coated PU sponge can reach a 32% reduction in peak heat release rate during cone calorimeter test, and prevent melt dripping after being ignited by a butane torch and the flame can be self-extinguished after the torch is removed. The resultant composite coating also demonstrates a killing rate of 99% against Staphylococcus aureus. Meanwhile, the coated PU sponge can retain the inherent elasticity and flexibility even after 500 cycles of compression. Furthermore, the coating materials are easily recyclable, which provide a useful reference for multifunctional treatment of sponge and cyclic utilization of resources. [ABSTRACT FROM AUTHOR]

An urgent need is to reduce the flammability of polymers and manage their toxic thermal decomposition products. Although conventional halogenated, metallic and phosphorus-based flame retardants (FRs) proved effective, they are known to cause major damage to human health and the environment. Containing carbon nanomaterials as a new class of flame retarding additives, polymer nanocomposites have displayed high flame retardancy, mechanical performance and electrical and thermal conductivity – a feat unmatched by conventional FRs. In this article we review very recent advances in carbon nanomaterials as FRs for polymers and composites as well as new understanding of the underpinning flame retarding mechanisms. Carbon nanomaterials, i.e. graphene, carbon nanotubes and carbon black, are discussed as the alternatives to conventional fillers due to their effectiveness in improving the polymers' flammability, mechanical properties and conductivity. The synergy between carbon-based nanofillers and conventional FRs is comprehensively reviewed, concluding that adding small fractions of carbon nanomaterials with conventional FRs into polymers can not only synergistically improve the flame retardancy but result in multifunctionalities such as thermal and electrical conductivity, without compromising the polymers' mechanical performance. Chemically or physically combining carbon nanomaterials with other compounds or nanoadditives containing phosphorus and nitorgen elements can create significant synergies for multifunctional polymers and composites to attain superior flame-retardant properties. [ABSTRACT FROM AUTHOR]

Organic-inorganic hybrid flame retardant technology integrates independent ingredients into a whole, thus showing advantage of simultaneous improvement in flame retardant, smoke suppressant and mechanical properties of polymers over traditional flame retardants. In this work, a novel organic-inorganic hybrid flame retardant denoted as IR-MOF-3-Mel was synthesized by covalent hybridization of isoreticular metal-organic framework-3 (IR-MOF-3) with melamine. A relatively low amount of IR-MOF-3-Mel nanoparticles dramatically decreased the fire risk of epoxy resin (EP). Specifically, the EP with only 2.0 wt% of IR-MOF-3-Mel achieved a limiting oxygen index (LOI) of 30.5% as well as a UL-94 V-0 classification, whereas its counterpart with 2.0 wt% of IR-MOF-3 showed a LOI of 25.0% and no classification in UL-94 test. Furthermore, the peak heat release rate, total heat release and smoke production rate of the EP with 2.0 wt% of IR-MOF-3-Mel was declined by 74.0%, 71.4% and 35.6%, respectively, compared to neat EP. Additionally, the glass transition temperature, the tensile strength, and the young's modulus were 11 °C, 38%, and 27% higher than those of neat EP, respectively. The flame retardant mechanism analysis clarified that IR-MOF-3-Mel contributed to formation of a char layer with a high level of thermal resistance and graphitization which accounted for significantly reduced fire risks. Image 1 • With only 1.5 wt% of IR-MOF-3-Mel, the EP composite achieved a UL-94 V-0 rating. • 2.0 wt% of IR-MOF-3-Mel leads to an unprecedented reduction in both PHRR (−74.0%) and THR (−71.4%) of epoxy composites. • IR-MOF-3-Mel hybrid also shows good smoke suppression effect. • 2.0 wt% of IR-MOF-3-Mel improves the tensile strength by 38% compared to neat EP. [ABSTRACT FROM AUTHOR]

Phosphonate esters may be used as flame retardants for flammable polymers, but always face low flame-retardant efficiency and melt dripping. Until now, no remarkable progress was made in solving the above two defects, thus tremendously affecting their applications as flame retardants. In current work, from the chemistry viewpoint, we designed and synthesized poly(2-butyne-1,4-diol phenylphosphonate) (PPBP) containing alkynyl group to break through above-mentioned defects. Compared with the corresponding control sample poly(1,4-butanediol phenylphosphonate) (PPBOP) without alkynyl, thermal analysis revealed that residual char of the PPBP with C C bonds increased to 45.0%, much higher than 1.6% for the PPBOP without C C bonds, and greatly increased by 27 folds. Various measurements and kinetic analysis were used to investigate the underlying cause for the leap in charring. It turns out that PPBP was involved in a unique decomposing and crosslinking process upon heating, which played a vital role in the leap in charring for PPBP. The leap in charring might afford polymers better flame retardancy through condensed phase. After incorporation of the PPBP into thermoplastic polyurethane (TPU), burning tests illustrated that PPBP not only endowed TPU with excellent flame retardancy and anti-melt dripping performance, but also resulted in extremely low heat release rate and smoke production rate, correspondingly decreased by 70.7% and 53.9% compared with those of TPU. Various measurements further confirmed that the charring caused by PPBP itself and the enhanced charring of TPU induced by PPBP played a crucial role in the remarkable superior flame retardancy of TPU/PPBP. [ABSTRACT FROM AUTHOR]

Metal organic frameworks (MOFs)-derived flame retardants have been recently emerged as a new class of additives in polymeric materials to reduce the fire hazard during application in situations that require high fire safety. In terms of tailored chemical components, tunable nanostructure and abundant porosity, MOFs-based flame retardants display charming features compared to the traditional ones. Typical MOFs, such as zeolitic imidazolate frameworks (ZIFs), MILs (MIL for Materials Institute Lavoisier), UiOs (UiO for University of Oslo), combined with newly designed counterparts, have been employed directly or utilized after modification in variety of universal plastics including epoxy resin, polyurethane, poly(lactic acid), polystyrene, etc. A work need to be come out to run through the research process and methods recently reported surrounding this novel technology. This review article born at the right moment aims to summarize the most relevant and up-to-date advances in MOFs and their derivatives for flame retardant polymeric materials mainly in the past three years. The main block sheds light on the mentality of designing for MOFs-based flame retardants via structural and molecular devise. Special attention will be paid to the flame retardant efficiency and corresponding mechanism of different kinds of MOFs-based flame retardants in polymer composites. The above introduction develops in line with pristine MOFs, MOFs as synergist, modified MOFs, MOFs' hybrids and MOF derivatives. Finally, we will provide a brief comment on forthcoming research opportunities and challenges for future growth of MOFs-based flame retardants in polymeric materials. Image 1 [ABSTRACT FROM AUTHOR]

To realize green, light weight, strong, tough and additional functionalities in polymer composites is challenging and has attracted great attention recently. Nature has provided perfect models such as mussel and silk to guide the design and fabrication of manmade materials with these merits. Herein, two bio-inspired strategies are combined to construct a strong, tough, and flame retarding composites. Mussel-adhesive-inspired polydopamine nanotube (PDANT) with high aspect ratio is first prepared by using a readily removable ammonium molybdate nanowire as template. PDANT/poly(vinyl alcohol) (PVA) composites with abundant and arranged interfacial hydrogen bonds (H-bonds) that mimic the hierarchically and densely assembled H-bonds in nanocrystallines reinforced spider silk are then fabricated by solution casting. Tensile test reveals that these designs have significantly improved the strength and ductility of composites as compared to neat PVA and polydopamine nanoparticles reinforced PVA. Moreover, limiting oxygen index and vertical burning test indicate that PDANT could also act as excellent flame retardant to enhance the flame resistance of composites, owing to the percolation network of PDANT in matrix and the good radical scavenging ability of PDANT. Our finding underlines the great potential of PDANT as green alternative of inorganic nanotubes for strong, tough, and flame retarding polymer composites. [ABSTRACT FROM AUTHOR]

Due to the worldwide awareness about environmental issues, there is an increasing demand for the development of low cost and ecofriendly materials. In this work, natural fabrics of Manicaria saccifera (MS), a palm tree from the Americas, were used to prepare polybenzoxazine-based bio-composites. These materials were initially developed as bidirectional alkaline-treated fabrics impregnated with benzoxazine resins (prepregs) and then cured in a hot-press. The good compatibility between matrix and reinforcement was confirmed by scanning electron microscopy (SEM), which showed that alkaline treatment led to a more homogeneous fabric surface, achieving improved interfacial interaction. The dynamic mechanical analysis revealed elevated glass transition temperatures (>115 °C) and crosslinking degrees. The results of tensile and flexural tests showed high elastic modulus, with values around 2 GPa. Thermal analyses indicate the great flame retardant performance of these bio-based materials due to their high char yields and LOI values. Therefore, this study suggests the elevate potential of these highly bio-based composites, comprising more than 60% of natural matter, to be used in high-performance applications, especially where flame-retardancy is required, like construction, aerospace or automotive industries. [ABSTRACT FROM AUTHOR]

The creation of high-performance polylactic acid (PLA) materials combining excellent mechanical robustness and flame-retardant performances are essential to meet demanding performances requirements for their practical applications in industry. Despite encouraging advances, current strategies by introducing toughening agents and flame retardants usually show compromised mechanical strength/ductility because of the irrational interphase reaction design of multi-component polymer blends. To date it remains challenging to robust and flame-retardant PLA via controlling interphase reactions. We, herein, report the rational design of mechanically robust and flame-retardant PLA by in situ manipulating interphase reactions between PLA, epoxidized soybean oil (ESO), a biobased and inexpensive toughening agent, and ammonia polyphosphate (APP), an effective eco-friendly flame retardant. We show that in addition to a high tensile strength of 42.0 MPa, as-designed PLA/ESO/APP ternary blend exhibits a high extensibility of 165% and a fracture toughness as high as 46 MJ/m3, which are respectively 21 and 14 folds of that of the bulk PLA. Meanwhile, a desired V-0 rating and a high limited oxygen index of 30.2% are achieved. Such outstanding performance portfolios are enabled by the rational manipulation of interphase reactions, leading to the in situ formation of favorable phase structures. This work offers an innovative methodology for facilely and massively creating high-performance multi-component polymer blends by tailoring interphase reactions, and contributes to expanding the extensive applications of PLA. Image 1 • Advanced PLA/ESO/APP ternary blends have been rationally designed via manipulating interphase reactions. • As-designed PLA/ESO/APP blend exhibits a large extensibility of 165% and a fracture toughness as high as 46 MJ/m3. • The PLA/ESO/APP ternary blend retains a high tensile strength of 42.0 MPa. • The PLA/ESO/APP blend can pass a V-0 rating in addition to showing a high LOI of 30.2%. [ABSTRACT FROM AUTHOR]

Fibre reinforced composites (FRCs) have been increasingly used in the prefabricated building (PB) industry owing to its high strength-to-weight ratio, ease of application and flexibility in manufacturing. FRCs can be used in PBs for both structural and non-structural applications. The major hindrance for composite elements in PB is their fire performance. Depending on applications, there will be different requirements for FRCs on the fire resistance and vertical flame spread. There is limited information available to structural and façade engineers/designers on fire safety of FRCs especially for PBs. Therefore, this paper provides the overview on the fire performance FRCs in PBs with a special focus on fibre reinforced polymer and textile reinforced concrete. • Fire performance of fibre reinforced composites (FRCs) • Structural and non-structural application of FRCs in prefabricated building (PB) • Basis fire design requirements for PB • Potential research studies needed for fire safety of PB with FRCs elements [ABSTRACT FROM AUTHOR]

A bio-flame retardant filler was synthesized via the self-polymerization of dopamine hydrochloride in alkaline condition, yielding nano-sized polydopamine (nano-PDA) particles ranging between 50 and 100 nm in diameters. Adding a small amount (2 wt%) of the nano-PDA particles into an epoxy can remarkably reduce the value of peak heat release rate by 53.6%, exceeding the performance aluminum trihydroxide (ATH) particles at 10 wt%. The significant improvement in flame retardancy at a relatively low loading of PDA has been found to originate from several key mechanisms including radical scavenging, higher char yield, and production of CO 2. Furthermore, the addition of nano-PDA in the epoxy resin increased the tensile strength by ~6%. In contrast, the addition of common flame retardant, such as ATH, to achieve the same increase in flame retardancy of epoxy would reduce the tensile strength by 22%. This improvement in mechanical properties is attributed to the better bonding between PDA particles with epoxy than ATH with epoxy. [ABSTRACT FROM AUTHOR]

Last years have witnessed great advances in minimizing the flammability of the polylactic acid (PLA) bioplastic. Unfortunately, to date there remains an urgent lack of a facile strategy to develop highly effective flame retardants for PLA. Herein, we report one-pot scalable fabrication of an oligomeric phosphoramide, phenyl phosphonic piperazine (PPP), via a one-step condensation polymerization. PPP can finely disperse within the PLA matrix showing a submicron-grained structure with a domain size of 100–300 nm. The addition of 3 wt% PPP increases the limiting oxygen index (LOI) of PLA to 32.5 vol%, and a V-0 rating is achieved. Such high flame retardancy is mainly attributed to the free radical quenching, gas dilution and the thermal barrier action of the char layer. Moreover, the PLA/3%PPP composite retains a tensile strength of 55.4 MPa. This work provides a facile and scalable approach to preparing high-performance flame retardant PLA materials. Image 1 • An oligomeric polyphosphoramide (PPP) was facilely synthesized by a one-pot condensation reaction. • The PLA/PPP composites exhibit unique submicron-grained microstructures. • Adding only 3 wt% PPP enables PLA to achieve V-0 rating and an LOI value as high as 32.5%. • The flame retardancy of PPP is mainly attributed to the radical quenching effect of and gas dilution effects. • The final PLA maintains high mechanical strength due to uniform dispersion of PPP and strong interfaces. [ABSTRACT FROM AUTHOR]

It is still a big challenge to develop high performance polymer foams with outstanding flame retardancy and high thermal stability through a facile strategy. Herein, starting from synthesizing phenylethynyl end-capped all-aromatic liquid crystalline polyester with good processability, a new kind of flame retarding liquid crystalline thermosetting foam (LCTF) was fabricated without adding additional flame retardant and foaming agent. LCTF simultaneously shows outstanding flame retardancy (UL94‒V0 grade, 36.4% of limit oxygen index), excellent smoke suppression and high thermal stability, which are the best values reported so far among intrinsic flame retarding foams. The mechanism of outstanding flame retardancy is revealed by investigating chemical and morphological structures with the aid of three-dimensional reconstruction of morphology. Roles from gas phase and condensed phase are proved to be responsible for unique flame retardancy. The application of LCTF in thermal insulation was also evaluated. Image 1 [ABSTRACT FROM AUTHOR]

A novel intumescent flame retardant (IFR) system composed of ammonium polyphosphate and poly (1,3-diaminopropane-1,3,5-triazine-o-bicyclic pentaerythritol phosphate) (APP/PDTBP) was mixed with polyethylene to prepare the continuous glass fibre reinforced polyethylene (CGF/PE) unidirectional prepregs by melt impregnation process, and then the CGF/PE/IFR composite laminate were consolidated by hot compression moulding method. The flame retardancy, thermal stability and mechanical properties of CGF/PE/IFR composite laminates were investigated by limiting oxygen index, vertical burning test, cone calorimetric test, thermogravimetric analysis, tensile and flexural strength tests, mode I interlaminar fracture toughness test, and scanning electron microscopy (SEM). The flame retardancy of CGF/PE composite laminates increased with the increase of IFR system loading, which attributes to the formation of intumescent char layer from flame retardants and the weakening of wicking actions of glass fibres. The mechanical properties increased and then decreased with addition of flame retardants, except for the flexural strength with continuous increase. The SEM images showed that IFR system had toughening effect and could improved the strength of fibre-matrix interface. Based on the mechanical properties and the flame retardancy, when the matrix contains 30 wt% IFR system, the CGF/PE/IFR composite laminate had the best comprehensive performance. Image 1 [ABSTRACT FROM AUTHOR]

In order to effectively reduce fire hazards while retaining excellent mechanical properties of flexible polyvinyl chloride (PVC), a novel core-shell-structured flame retardant, i.e., activated carbon spheres-supported NiCo 2 (CO 3) 1·5 (OH) 3 hybrid material (ACS@BNCC), was synthesized and dry-modified by 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquids ([BMIM] PF 6) before mixing with PVC. The results of the limiting oxygen index (LOI) and cone calorimeter test (CCT) showed that 2 phr ILs-ACS@BNCC could endow PVC with outstanding fire-resistant and smoke suppression properties. The synergistic effect of ACS@BNCC and [BMIM] PF 6 increased the LOI to 29.1%, and reduced the peak heat release rate, peak smoke production rate, and total smoke production of pure PVC by 37.0%, 62.0%, and 45.1%, respectively. The flame retardant mechanism was proposed. The 2 phr ILs-ACS@BNCC mainly had physical barrier, catalytic carbonization, endothermic and dilution effects. In addition, since [BMIM] PF 6 enhanced the interface compatibility between PVC and ACS@BNCC, the tensile strength, elongation at break, and impact strength of 2 phr ILs-ACS@BNCC/PVC were significantly improved compared with those of ACS@BNCC/PVC. This kind of PVC composite with outstanding flame retardant, smoke suppression and mechanical properties will substantially expand the application of PVC. Image 1 • A perfect core-shell flame retardant ACS@BNCC was designed and synthesized. • ACS@BNCC and [BMIM] PF 6 exerted a synergistic flame retardant effect in PVC. • The flame-retardant mechanism of ILs-ACS@BNCC was proposed. • The mechanical property of PVC was improved due to the presence of [BMIM] PF 6. [ABSTRACT FROM AUTHOR]

This study addresses three very important aspects of sustainable development of new flame re-tardant material, i.e. in situ solvent free synthesis of flame retardant macromolecules during thermal processing of polymers, their leaching behavior from the polymer matrix and their preliminary toxicity assessment. Polyamide 6 (PA6) was functionalized by a novel reactive extrusion process. In situ synthesis of phosphine oxide based macromolecules was obtained via Michael addition reaction of divinyl phenyl phosphine oxide (DVPPO) and piperazine during the reactive extrusion process. The formation of phosphine oxide macromolecules (oligomers and low molecular weight polymers) were confirmed by NMR study of the modified PA6 polymer and UPLC-MS analysis of extracts from PA6 samples. Elemental analysis of the modified PA6 after the extraction with chloroform and water confirmed retention of majority of phosphorus species, confirming the beneficial effect of large macromolecular additives. This non-leaching behavior of modified PA6 is an important requirement for thin walled substrates like fibers and films where long-term durability is very important. The reactive extruded PA6 was successfully processed into textile fibers via melt spinning process in a laboratory spinning plant. The presence of phosphine oxide macromolecules in PA6 matrix had a lubricating effect, which has influence in the thermal processing and final properties of the fiber. The modified PA6 was evaluated for fire performance in small-scale fire tests where it showed improved fire performance. Moreover, the preliminary toxicity assessment of the relatively unknown DVPPO, via a well-established in vitro platform showed no adverse effects on cell viability. Image 1 [ABSTRACT FROM AUTHOR]

It is a challenge to prepare a flame retardant polymer membrane with high transparency through addition of flame retardants all the time. In the present paper, a compounding method based on hydrogen bonding complexation is used to realize molecule-scale dispersion of a N–P flame retardant (guanidine phosphate (GP)) in poly(vinyl alcohol) (PVA) membrane by the interaction of their intermolecular hydrogen bonds. In this way, a PVA membrane with high transparence can be successfully obtained. Vertical combustion, micro-scale combustion calorimetric, thermo-gravimetric analysis, Fourier transform infrared spectroscopy and scanning electron microscope are employed to evaluate the flame retardancy and analyze the corresponding mechanisms. The GP flame retardant PVA membrane with high transparence improves the tensile strength by 47% and achieves UL94 VTM-0 rating when the content of GP is 15 wt%. It shows that the interaction between GP and PVA effectively promote formation of the continuous and stable char in the condensed phase. [ABSTRACT FROM AUTHOR]

Polyether amine (PEA) was chemically introduced onto urea-formaldehyde (UF) chains for the purpose of toughening UF foams via reactions of PEA involved hydroxymethylation and condensation in UF system. Through introduction of PEA component, the curing process of UF-b-PEA proceeded within a broader temperature range, and the curing peak shifted to a higher temperature. Compared with neat UF foam, UF-b-PEA foams exhibited polygonal open cells with larger cell size, longer strut length and higher open porosity. During cyclic compression, the Mullins effect and the area in the hysteresis loop were reduced for UF-b-PEA foam, indicating outstanding compression resilience and compressive stability of the foam. Due to the open-cellular structure of foam and excellent flexibility of PEA component, the critical force of Euler buckling (F c) decreased obviously, indicating the deformability of UF-b-PEA foams was improved without fracture of strut during reversible deformation. Besides, UF-b-PEA foams showed outstanding flame retardancy. Image 1 [ABSTRACT FROM AUTHOR]

The SiO 2 @metal organic framework (Universitetet i Oslo-66, UiO-66) core–shell microspheres were constructed through covalent linkage between amine groups in UiO-66-NH 2 and epoxy groups on the surface of silica. The morphology and size of the SiO 2 @UiO-66 core–shell microspheres could be simply controlled by tuning the ratio between UiO-66-NH 2 and epoxy terminated silica (E-SiO 2). As observed by TEM, the SiO 2 @UiO-66 hybrids showed better dispersion state within epoxy matrix compared to either E-SiO 2 or UiO-66-NH 2. The incorporation of SiO 2 @UiO-66 hybrids slightly promoted the thermal degradation of the resultant epoxy composites but improved residual yield. The dynamic mechanical analysis results indicated that the SiO 2 @UiO-66 hybrids slightly increased the glass transition temperature and the modulus. The SiO 2 @UiO-66 hybrids exhibited higher efficiency in reducing the heat release rate and the smoke production rate compared to either E-SiO 2 or UiO-66-NH 2. The influence of the component ratio in SiO 2 @UiO-66 on flame retardancy of the epoxy composites was also studied by cone calorimeter. Specifically, the SiO 2 @UiO-66 hybrid with medium ratio (SiO 2 @UiO-66-2) exhibited maximum reduction in peak heat release rate (−31%), total heat release (−23%) and total smoke production (−16%). The char residues were investigated by the Fourier transform infrared spectra, scanning electron microscopy and X-ray photoelectron spectroscopy, which demonstrated that the enhanced flame retardancy of EP/SiO 2 @UiO-66-2 was attributable to the continual morphology and high thermal resistance originated from the presence of the silicon and zirconium complex. These favorable characteristics including high flame retardant efficiency and good smoke suppression make SiO 2 @UiO-66 hybrids promising for flame retardant polymers application. • The SiO 2 @UiO-66 hybrids showed core–shell microsphere structure. • The addition of 3 wt% SiO 2 @UiO-66-2 caused 31% reduction in peak heat release rate. • The addition of 3 wt% SiO 2 @UiO-66-2 led to 16% reduction in total smoke production. [ABSTRACT FROM AUTHOR]