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

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

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

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

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

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

Developing highly efficient and multifunctional epoxy resins (EPs) that overcome the shortcomings of flammability and brittleness is crucial for pursuing sustainable and safe application but remains a huge challenge. In this paper, a novel biomass-containing intumescent flame retardant containing a rigid–flexible and multi-siloxane bridge structure (DPB) was synthesized using siloxane; 9,10-dihydro-9-oxa-10-phosphaphenanthrene 10-oxide (DOPO); and biomass vanillin. DPB could facilitate the formation of a carbon residual with an intumescent structure, which effectively blocked the propagation of heat and oxygen. As a result, the peak heat release rate (pHRR) and total heat release (THR) of DPB/EP-7.5 decreased by 38.8% and 45.0%, respectively. In terms of mechanical properties, the tensile and flexural elongations at break of DPB/EP-7.5 increased by 77.2% and 105.3%, respectively. Impressively, DPB/EP-7.5 had excellent dielectric properties, with a dielectric constant of 2.5–2.9. This was due to the Si-O bonds (multi-siloxane bridges) contained in DPB/EP, which can quench the polarization behavior of the hydroxyl group. This paper provides a facile strategy for the preparation of multifunctional EP, which will pave the way for the promotion and application of EP in the high-end field. [ABSTRACT FROM AUTHOR]

One of the current challenges in the development of flame retardants is the preparation of an environmentally friendly multi-element synergistic flame retardant to improve the flame retardancy, mechanical performance, and thermal performance of composites. This study synthesized an organic flame retardant (APH) using (3-aminopropyl) triethoxysilane (KH-550), 1,4-phthalaadehyde, 1,5-diaminonaphthalene, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as raw materials, through the Kabachnik-Fields reaction. Adding APH to epoxy resin (EP) composites could greatly improve their flame retardancy. For instance, UL-94 with 4 wt% APH/EP reached the V-0 rating and had an LOI as high as 31.2%. Additionally, the peak heat release rate (PHRR), average heat release rate (AvHRR), total heat release (THR), and total smoke produced (TSP) of 4% APH/EP were 34.1%, 31.8%, 15.2%, and 38.4% lower than EP, respectively. The addition of APH improved the mechanical performance and thermal performance of the composites. After adding 1% APH, the impact strength increased by 15.0%, which was attributed to the good compatibility between APH and EP. The TG and DSC analyses revealed that the APH/EP composites that incorporated rigid naphthalene ring groups had higher glass transition temperatures (Tg) and a higher amount of char residue (C700). The pyrolysis products of APH/EP were systematically investigated, and the results revealed that flame retardancy of APH was realized by the condensed-phase mechanism. APH has good compatibility with EP, excellent thermal performance, enhanced mechanical performance and rational flame retardancy, and the combustion products of the as-prepared composites complied with the green and environmental protection standards which are also broadly applied in industry. [ABSTRACT FROM AUTHOR]

To solve the problems of low flame retardant efficiency and weak low-temperature performance of asphalt modified by conventional flame retardants (CFR), in this study, halloysite nanotubes (HNTs) and CFR were used to prepare nanocomposite flame retardants (NCFR) to modify asphalt. A fluorescence microscope (FM), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscope/energy dispersive spectrometer (SEM/EDS) were used to characterize the microstructure of NCFR-modified asphalt. An oxygen index meter, Cleveland open cup, and cone calorimeter were used to test the flame retardant properties of the asphalt. A dynamic shear rheometer, bending beam rheometer, and force ductility tester were used to test the rheological properties of asphalt. At the same time, flame retardant–modified asphalt mixtures were prepared to verify the flame retardancy and road performance of the flame retardant–modified asphalt. The research results showed that the asphalt modified with 8% CFR and 1% HNTs (MA/CFR/1% HNTs) showed better dispersibility. The increase of limiting oxygen index and self-ignition temperature and the decrease of heat release rate and smoke production rate of MA/CFR/1% HNTs indicated that it has good flame retardancy. At 64°C, compared with modified asphalt (MA), the rutting factor of MA/CFR/1% HNTs increased by 88.17%, the creep recovery increased, and the irreversible creep decreased, indicating that its high-temperature performance improved significantly. At −18°C , compared with that of MA/CFR, the low-temperature creep stiffness of MA/CFR/1% HNTs decreased by 36 MPa and the creep rate of MA/CFR/1% HNTs increased by 0.034, indicating that only 1% HNTs can improve the effect of degraded CFR on the low-temperature performance of MA. Simultaneously, MA/CFR and MA/CFR/1% HNTs can improve the high-temperature performance and water stability of asphalt mixtures. Adding 1% HNTs to a MA/CFR-modified asphalt mixture can improve the low-temperature performance of the asphalt mixture to the level of the low-temperature performance of the modified asphalt mixture. In summary, the modification of asphalt with 1% HNTs and 8% CFR can effectively improve the flame retardant efficiency and significantly improve the road performance of asphalt. [ABSTRACT FROM AUTHOR]

Blends of tannic acid （TA) /poly(vinyl alcohol）（PVA） are prepared by compression molding and the effect of different TA/PVA ratios on the flame retardant properties of the TA-PVA blends is studied. The flammability of TA-PVA blends is assessed using cone calorimetry， thermogravimetric analysis （TGA), differential scanning calorimetry （DSC)，UL-94 tester and LOI tester. The addition of TA can improve the flame retardancy of PVA through hydrogen bonding between TA and PVA. The more the content of TA in the TA-PVA blends, the better the thermal stability of TA-PVA and the glass transition temperature of TA-PVA. When the ratio of n（TA) ∶ n(PVA）is 1∶50， the LOI value of TA-PVA is 31. 6% and UL-94 grade reaches V-1 level， the peak heat release rate of TA-PVA decreases from 634. 9 kW/m² to 328. 1 kW/m² and smoke production rate decreases from 0. 18 m² /s to 0. 10 m2 /s. [ABSTRACT FROM AUTHOR]

ZIF-8@APP was prepared by in situ growth of ZIF-8 on the surface of ammonium polyphosphate (APP) through co-precipitation method. The ZIF-8@APP/EP composites were prepared by adding ZIF-8@APP into epoxy resin (EP). The composites with loading of ZIF-8@APP showed good flame retardancy, smoke suppression and mechanical properties simultaneously. The limiting oxygen index (LOI) of the flame retarded composites containing 10 wt% of ZIF-8@APP was 32.6% and the UL-94 test reached V-0. Meanwhile, the peak heat release rate and total heat release of the composites with 5 wt% of ZIF-8@APP were reduced by 60.8 and 35.5% compared with pristine epoxy resin. The ZIF-8 particles on APP improved interface actions between APP and EP matrix, which led to the enhancement in mechanical properties of the flame-retardant composites. [ABSTRACT FROM AUTHOR]

In this article, rigid polyurethane foams obtained with the addition of a bio-polyol from rapeseed oil, were modified with the dimethyl propane phosphonate as additive flame retardant and two reactive flame retardants diethyl (hydroxymethyl)phosphonate and diethyl bis-(2-hydroxyethyl)-aminomethylphosphonate. The influence of used flame retardants on the foaming process and characteristic processing times of tested polyurethane systems were determined. The obtained foams were tested in terms of cell structure, physical and mechanical properties, as well as flammability. Modified foams had worse mechanical and thermal insulation properties, caused by lower cellular density and higher anisotropy coefficient in the cross-section parallel to the foam rise direction, compared to unmodified foam. However, the thermal conductivity of all tested foam materials was lower than 25.82 mW/m∙K. The applied modifiers effectively reduced the flammability of rigid polyurethane foams, among others, increasing the oxygen index above 21.4 vol.%, reducing the total heat released by about 41–51% and the rate of heat release by about 2–52%. A correlation between the limiting oxygen index values and both total heat released parameters from the pyrolysis combustion flow calorimetry and cone calorimetry was observed. The correlation was also visible between the value of the heat release capacity (HRC) parameter obtained from the pyrolysis combustion flow calorimetry and the maximum average rate of heat emission (MARHE) from the cone calorimeter test. [ABSTRACT FROM AUTHOR]

The use of flexible polyurethane foam (FPUF) is severely limited due to its flammability and dripping, which can easily cause major fire hazards. Therefore, choosing an appropriate flame retardant to solve this problem is an urgent need. A coating was prepared on the FPUF surface by dipping with phytic acid (PA), Fe2(SO4)3·xH2O, and laponite (LAP). The influence of PA-Fe/LAP coating on FPUF flame-retardant performance was explored by thermal stability, flame retardancy, combustion behavior, and smoke density analysis. FPUF/PA-Fe/LAP has a good performance in the small fire test, which can pass the UL-94 V-0 rating and the limiting oxygen index reaches 24.5%. Meanwhile, the peak heat release rate values and maximum smoke density of FPUF/PA-Fe/LAP are reduced by 38.7% and 38.5% compared with those of neat FPUF. After applying PA-Fe/LAP coating, the value of fire growth rate index decreases from 10.5 kW/(m2·s) to 5.1 kW/(m2·s), dramatically reducing the fire risk. Encouragingly, the effect of PA-Fe/LAP coating on cyclic compression and permanent deformation is small, which is close to that of neat FPUF. This work provides an effective strategy for making a flame-retardant FPUF with antidripping and keeping mechanical properties. [ABSTRACT FROM AUTHOR]

A novel bio-based flame retardant designated AVD has been synthesized in a one-pot process via the reaction of 9,10-dihydro-9-oxa-10-phospha-phenanthrene-10-oxide (DOPO), vanillin (VN), and 2- aminobenzothiazole (ABT). The structure of AVD was confirmed using Fourier transform infrared spectroscopy (FTIR), and 1H and 31P nuclear magnetic resonance spectroscopy (NMR). The curing process, thermal stability, flame retardancy, and mechanical properties of the epoxy resin (EP) modified with AVD have been investigated comprehensively. The extent of curing, the glass transition temperature and the crosslinking density of the blend decreased gradually with increasing AVD content. The thermogravimetric analysis (TGA) was used to demonstrate that the presence of AVD reduced the thermal decomposition rate for EP and enhanced the formation of carbon residue during resin decomposition. A blend of 7.5 wt% AVD (0.52% phosphorus) displays a UL-94V-0 rating and a LOI of 31.1%. Reduction of the peak heat release rate, total heat release rate and total smoke production was 41.26%, 35.70%, and 24.03%, respectively, as compared to the values for pure EP. The improved flame retardancy of the flame retardant epoxy (FREP) may be attributed to the formation of a compact and continuous protective char layer into the condensed phase as well as the release of non-combustible gases and phosphorus-containing radicals from the decomposition of AVD in the gas phase. AVD is a new and efficient biobased flame retardant for epoxy with great prospects for industrial applications. [ABSTRACT FROM AUTHOR]

This paper provides understanding of the fire performance of exposed cross-laminated-timber (CLT) in large enclosures. An office-type configuration has been represented by a 3.75 by 7.6 by 2.4 m high enclosure constructed of non-combustible blockwork walls, with a large opening on one long face. Three experiments are described in which propane-fuelled burners created a line fire that impinged on different ceiling types. The first experiment had a non-combustible ceiling lining in which the burners were set to provide flames that extended approximately halfway along the underside of the ceiling. Two further experiments used exposed 160 mm thick (40-20-40-20-40 mm) loaded CLT panels with a standard polyurethane adhesive between lamella in one experiment and a modified polyurethane adhesive in the other. Measurements included radiative heat flux to the ceiling and the floor, temperatures within the depth of the CLT and the mass loss of the panels. Results show the initial peak rate of heat release with the exposed CLT was up to three times greater when compared with the non-combustible lining. As char formed, this stabilised at approximately one and a half times that of the non-combustible lining. Premature char fall-off (due to bond-line failure) was observed close to the burners in the CLT using standard polyurethane adhesive. However, both exposed CLT ceiling experiments underwent auto-extinction of flaming combustion once the burners were switched off. [ABSTRACT FROM AUTHOR]

[Display omitted] • An organophosphinic acid salt flame retardant DPM was facilely synthesized. • DPM promoted the curing process of epoxy resins. • The low addition of DPM resulted in excellent flame retardancy. • The addition of DPM increased both strength and toughness. Achieving flame retardancy in epoxy resin (EP) while preserving its essential properties, including strength, toughness, and thermal stability, offers considerable challenges in the application of flame retardant EP modifications. In this study, we were successful in synthesizing a novel ionic-based flame retardant, organophosphinic acid salt (DPM), using a simple ionic reaction. DPM possesses a unique structure consisting of rigid groups and flexible chain segments. Fourier transform infrared (FTIR) and nuclear magnetic resonance (NMR) techniques were used to characterise the structure of DPM. Incorporating DPM into the EP yielded remarkable improvements in mechanical properties, reduced fire hazard, enhanced processability, a lower curing temperature, and good thermal stability. The EP/DPM-7.5 composites demonstrated excellent flame retardancy by effortlessly achieving a V-0 rating in vertical combustion (UL-94) testing, while an impressive limited oxygen index (LOI) value of 36.3% was attained, a substantial 42.4% enhancement compared to the EP. Moreover, cone calorimeter (CC) tests revealed that EP/DPM-7.5 exhibited a 41.7% decrease in peak heat release rate (PHRR), a decreased fire growth rate index (FIGRA), and an increased fire performance index (FPI). Additionally, the tensile strength and flexural strength of EP/DPM-7.5 improved by 26.0% and 23.7%, respectively. Comparatively, EP/DPM-5 maintained the glass transition temperature (T g) and thermal stability of the EP while significantly enhancing the impact strength by 85.4%. The newly developed flame retardant, DPM, exhibited excellent comprehensive performance and fire safety characteristics, thereby demonstrating the significant potential for practical applications in flame retardant EP systems. [ABSTRACT FROM AUTHOR]

Polyurea (PU) elastomers have become increasingly popular in recent years due to their exceptional blast mitigation, ballistic protection, and wear resistance properties. However, their applications as protective materials are often limited as a result of their high flammability. In this study, aromatic dianhydrides (ArDAs) were employed to capture the thermal decomposing products of PU during combustion and facilitate the generation of highly heat-resistant aromatic polyimides (i.e., end group capturing effect), thus enhancing the material's char-forming ability and improving its flame retardancy. The ArDAs were found to significantly reduce the peak heat release rate (PHRR), total heat release (THR), total smoke release (TSR), and total CO release (TCO) of PU, and meanwhile increased the amount of char residue. At 20 wt% content of 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA), PHRR, THR, TSR and TCO of PU were reduced by 70.6%, 32.5%, 44.7% and 58.8%, respectively, the char residue was increased by 405%, and the mechanical properties of PU were well maintained (88.5% tensile strength and 91.0% elongation at break of pure PU). These findings demonstrate that ArDAs could serve as a new kind of halogen/phosphorus-free flame retardant for PU elastomers. [Display omitted] • Novel halogen/phosphorus-free flame retardants were designed for PU elastomers. • The flame retardant mechanism is end group capturing by aromatic dianhydrides (ArDAs). • PHRR, THR, TSR and TCO were simultaneously reduced, and char residue was improved. • Both excellent flame retardant property and high mechanical property were achieved. [ABSTRACT FROM AUTHOR]

A rigid aromatic phosphorus‐containing hyperbranched flame retardant structure is synthesized from 10‐(2,5‐dihydroxyphenyl)‐10H‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO‐HQ), tris(4‐hydroxyphenyl)phosphine oxide (THPPO), and 1,4‐terephthaloyl chloride (TPC). The resulting poly‐(DOPO‐HQ/THPPO‐terephthalate) (PDTT) is implemented as a flame retardant into an epoxy resin (EP) at a 10 wt% loading. The effects on EP are compared with those of the monomer DOPO‐HQ and triphenylphosphine oxide (OPPh3) as low molar mass flame retardants. The glass transition temperature, thermal decomposition, flammability (reaction to small flame), and burning behavior of the thermosets are investigated using differential scanning calorimetry, thermogravimetric analysis, pyrolysis combustion flow calorimetry, UL 94‐burning chamber testing, and cone calorimeter measurements. Although P‐contents are low at only 0.6 wt%, the study aims not at attaining V‐0, but at presenting a proof of principle: Epoxy resinswith PDTT show promising fire performance, exhibiting a 25% reduction in total heat evolved (THE), a 30% reduction in peak heat release rate (PHRR) due to flame inhibition (21% reduction in effective heat of combustion (EHC)), and an increase in Tg at the same time. This study indicates that rigid aromatic hyperbranched polymeric structures offer a promising route toward multifunctional flame retardancy. [ABSTRACT FROM AUTHOR]

Phenoxy-phosphazene (PPZ) oligomer (Rabitle® FP100) flame retardant (FR) was successfully incorporated into the colorless and transparent semi-alicyclic polyimide (CPI) film matrix derived from 1,2,4,5-cyclohexanetetracarboxylic dianhydride (CHDA) and 4,4'-oxydianiline (ODA) (PI-a, CHDA-ODA). The PPZ FR showed good miscibility with the PI-a matrix with a loading amount of up to 10 wt% in the composite films. PI-b (CHDA-ODA-FP100-5) film maintained good optical properties with the transmittance of 83.9% at the wavelength of 400 nm, the yellow index (b*) of 3.28, and the haze of 2.14%. PI-b film also showed good flame retardancy with the limiting oxygen indices (LOI) of 41.2% and the flammability rating of UL94 VTM-0. In addition, PI-b film exhibited the obviously reduced heat release rate (HRR) and total smoke production (THR) during the cone calorimeter measurement. At last, PI-b showed the glass transition temperature (Tg) and 5% weight loss temperature (T5%) of 325.0 and 404.3 °C, respectively, which was slightly lower than those of the pristine PI-a film (Tg = 346.8 °C; T5% = 431.6 °C). Continuous PI-b films with a length of 1000 m and a width of 1000 mm were successfully obtained on the demonstration production line by optimizing the processing parameters via the modified solvent cast technology. Similar thermal, optical, and flame retardancy properties and obviously improved tensile properties were observed for the mass production of PI-b film. [ABSTRACT FROM AUTHOR]

Gymnasts can have high exposures to flame retardants (FRs), which are used in gymnastics safety equipment such as the loose foam pit. Therefore, we aimed to reduce gymnast exposure to FRs by replacing the foam in the pit using foam free of additive FR and measuring personal exposure during practice using hand-wipes. To assure maintenance of fire safety we first conducted a flammability study and facilitated a fire inspection for our partner gym. The FR-treated cubes had similar heat release rates to the non-FR treated cubes, required a 11 cm larger flame size applied for 6 s longer to ignite, and took 4 min longer to reach peak flame height. Based on these findings and the presence of other fire safety measures including smoke detectors and a sprinkler system, the local fire and building departments approved replacement of the foam pit with FR-free foam. We then replaced foam in the gym's pit, verified it was free of any additive FRs, and quantified common halogenated and organophosphate FRs on hand-wipes collected from ten collegiate gymnasts before and after practice, pre- and post-intervention. We observed a 5-fold decline in the median mass of FRs found in pit foam that accumulated on hand-wipes during practice among gymnasts who used the foam pit (p = 0.02), indicating that replacing the foam in a pit using materials free of FRs can reduce gymnast exposure to these chemicals during practice. Unlabelled Image • Gymnasts can have elevated exposures to flame retardants from foam pits. • Foam pits with and without flame retardants had similar heat release rates. • We replaced a foam pit in a gym with foam free of additive flame retardants. • Gymnast flame retardant exposure declined 5 fold from this intervention. [ABSTRACT FROM AUTHOR]

[Display omitted] • A novel phosphorus-containing tertiary amine hardener (DCM) is synthesized. • DCM endows epoxy resin with desired heat resistance and char-forming capacity. • DCM improves the mechanical stiffness, robustness and toughness of epoxy resin. • DCM imparts superior flame retardancy and smoke suppression to epoxy resin. Although current phosphorus (P)-based hardeners endowed epoxy resins (EPs) with intrinsic flame retardancy, their addition usually reduced thermal and mechanical properties. In this work, a novel phosphorus-containing tertiary amine hardener (DCM) was synthesized using diphenylphosphinic chloride and 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30), and applied to fabricate high-performance EP/DCM. Introducing P-containing group reduced the reactivity of tertiary amine of DCM, but EP/DCM gelled at 100 °C within 11.3 min, showing modest-temperature curing character. EP/DCM exhibited higher glass-transition temperature (T g) and char yield than virgin EP/DMP-30. Moreover, EP/DCM featured superior mechanical properties, of which the tensile strength, elongation at break and impact strength increased by 61.2%, 72.0% and 198.5%, respectively, relative to those of EP/DMP-30. DCM endowed EP thermosets with remarkable flame retardancy and smoke suppression. The limiting oxygen index (LOI) and UL-94 rating of EP/DCM reached 35.7% and V-0, respectively, with 36.2% and 22.6% reductions in peak heat release rate (PHRR) and peak smoke production rate (PSPR) compared with those of EP/DMP-30. This work pioneers an innovative strategy for creating high-performance EPs with satisfactory heat resistance, fire safety, and mechanical properties by curing with P-containing tertiary amine hardeners. [ABSTRACT FROM AUTHOR]

• Phosphorus-containing 1-vinylimidazole salts are synthesized as crosslinking agents for vinyl ester resins. • Interchain ionic interactions are constructed in vinyl ester resins for the first time. • Highly flame-retardant vinyl ester resins with well-balanced comprehensive performance are obtained. Flame-retardant vinyl ester resins (VER) have long been studied, however, very few flame retardants can efficiently improve the flame retardancy of the resin without deteriorating their other performance. In this work, a kind of liquid phosphorus-containing 1-vinylimidazole salt (called VC) was synthesized in a facile way with a very high yield. Then, VC was used as the flame-retardant crosslinking agent to obtain flame-retardant VER. Curing behaviors, flame retardancy, thermal stability, thermomechanical properties, and mechanical performance of the resin were investigated. VC had good compatibility with VER and the mixture presented a relatively low viscosity. VC/VER showed a high curing activity and can be efficiently cured in moderate conditions. VC was incorporated into the resin mainly by ionic bonds, by which interchain ionic interactions were constructed in the resin. With only 15 wt% additions of VC, the cured VC15/VER easily passed the UL 94 V0 rating and achieved a limiting oxygen index value of 32.7%. In the cone calorimetric test, VC15/VER severally presented a reduction in the peak heat release rate, total heat release rate, and total smoke release rate of 67.8%, 17.1%, and 27.3% compared to VER. VC15/VER showed good thermal stability, had a glass transition temperature of 151 °C (that of VER was 137 °C), and achieved high mechanical performance that can be comparable to VER. Hence, this work proposes a facile strategy for producing flame-retardant thermosets with well-balanced comprehensive performance, which exhibits potential in coatings, composites, and laminates for versatile applications. [ABSTRACT FROM AUTHOR]

[Display omitted] • A cubic metal organic flame retardant with single crystal structure and rich in nitrogen was synthesized by hydrothermal method. • The peak heat release rate of EP composite loaded with 9 phr R1-MOF decreased by 51.3%. • Flame retardant shows high flame retardancy and smoke suppression performance, and significantly reduces the toxicity of EP. • Synergistic flame retardancy between N element and metal ions in metal organic framework ligands. Toxic substances released during the combustion of epoxy resin (EP) not only cause casualties, but also pollute the environment. Hence, aiming at the flammability of EP, a new triazine based metal organic framework (R1-MOF) was successfully synthesized by solvothermal method to reduce the fire resistance of EP. The single crystal structure of MOF was determined by X-ray single crystal diffraction, and the regular hexahedral structure of the crystal was determined by scanning electron microscope. The peak heat release rate, smoke generation rate, CO generation and CO 2 generation of EP composite loaded with 9 per 100 parts of matrix resin (phr) of R1-MOFs were decreased by 51.3, 41.5, 45.3, and 39.1%, respectively, showing high flame retardancy and smoke suppression performance, and significantly reducing the toxicity of EP. It mainly benefited from the flame retardant N element in MOF ligand and the synergistic effect between ligand and metal ions. In this study, a new type of MOF flame retardant was proposed, which provided a new way to design efficient flame retardants, smoke suppressants and detoxification flame retardants. [ABSTRACT FROM AUTHOR]

As one of the most widely used polymers, the intrinsic brittleness and high flammability bring about a stringent requirement for the practical application of epoxy resins (EPs). It is difficult to toughen EP without compromising its mechanical and thermal properties for many conventional toughening agents. Here, a novel furan-derived bio-based polyphosphazene (PFMP) with a flexible backbone and rigid side groups was prepared by the nucleophilic substitution reaction between polydichlorophosphazene (PDCP) and furfuralcohol. The resultant PFMP was incorporated into EP to realize exceptional toughening, strengthening, and flame retardant function. By adding 15% of PFMP, the limit oxygen index value is from 25% (EP) to 33% (EP/PFMP-15) and reaches the UL-94 V-0 rating. According to the cone calorimeter results, EP/PFMP-15 exhibits exceedingly reduced peak heat release rate (pHRR) (50.2%) and total heat release (THR) (49.6%). The significantly increased fire performance index (FPI) and decreased fire growth rate index (FIGRA) of EP/PFMP-15 demonstrate an improvement in its flame retardancy. The catalytic carbonization effect (condensed phase) and radical quenching effect (gas phase) of PFMP account for the greatly improved flame retardancy. Moreover, the impact and tensile tests indicate that PFMP can ameliorate the mechanical performance of EP with a maximum increase of impact strength (111.8%) and elongation at break (35.2%) for EP/PFMP-5. With 15% PFMP added, the tensile strength of EP/PFMP-15 increases by 40.4%. This work demonstrates that PFMP is expected to overcome shortcomings (flammability, toughness, and strength) of EP and spread its applied fields. [Display omitted] • Bio-based polyphosphazene with furfuralcohol side groups (PFMP) was synthesized. • PFMP exhibits evident flame retardant and mechanical enhancement effect on epoxy resins (EP). • The peak heat release rate of EP/PFMP-15 was 50.2% lower than pure EP. • The impact strength of EP/PFMP-5 was 111.8% higher than pure EP. [ABSTRACT FROM AUTHOR]

[Display omitted] • A new flame retardant DOPONH 2 -S was synthesized. • It solved the problems of epoxy resin (EP) including flammability and brittleness. • DOPONH 2 -S achieved high efficiency in reducing THR, P -HRR and EHC of EP. • DOPONH 2 -S increased the impact strength and thermal stability of EP. Epoxy resin (EP) has two shortcomings: flammability and brittleness. Previous studies have improved brittleness or flame retardancy but they will compromise the glass transition temperature (T g) and thermal stability. Herein, a novel DOPO based phosphorus-, nitrogen- and sulfur-co-contained macromolecular flame retardant (DOPONH 2 -S) was synthesized and incorporated into EP to improve its flame retardancy and toughness with not damaging T g and thermal stability. After curing, both T g and the tensile strength of EP-2 improved at the addition of DOPONH 2 -S is 6.75 wt%. Simultaneously, the thermogravimetric analysis (TGA) results showed DOPONH 2 -S is helpful increasing the thermal stability of EP composites and protecting the polymer from further decomposition. In the fire safety test, EP-2 achieved V-0 rating in the vertical burning test and obtained a limiting oxygen index value of 30.5%. In comparison with pure EP, the peak heat release rate, total heat release and effective heat of combustion of EP-4 incorporated with 10.0 wt% DOPONH 2 -S were reduced by 59.1%, 58.5% and 46.3%, respectively. A two-phase mechanism was discussed to explain the combination effect in DOPONH 2 -S. In condensed-phase, rich char residue prevents the exchange of mass and heat during combustion. It also obstructs the release of combustible gases into the combustion zone. In gas-phase, the produced phosphorus- and sulfur-containing free radicals can capture active free radicals (H· and OH·), thus ending the chain reaction of combustion. Moreover, the addition of DOPONH 2 -S apparently improved the impact strength (62.5%). This work provided ideas for the development of multifunctional EP. [ABSTRACT FROM AUTHOR]

Although flame retardants are very effective in reducing the fire hazard of polymeric materials, their presence may be detrimental to mechanical strength. Hence, in order to have a holistic improvement of performance properties, a new approach has been developed wherein biochar is used to host a naturally-occurring flame retardant (lanosol). The issue of loss in mechanical strength of a polymer host is alleviated by the use of biochar. Three different doping procedures were investigated, namely, dry mixing, and chemical and thermal-based doping, to integrate lanosol into the biochar pores. The doped biochar was used to develop wheat gluten-based blends. The mechanical and flammability properties of the blends were assessed. It was found that thermal doping was the most effective in introducing significant amounts of lanosol particles inside the biochar pores. The bioplastic containing chemically, and thermally doped biochar had equal tensile strength (5.2 MPa), which was comparable to that of the unmodified material (5.4 MPa). The thermally doped biochar displayed the lowest cone calorimeter peak heat release rate (636 kW m−2) for combustion and the highest apparent activation energy (32.4 kJ mol−1) for decomposition. Thus, for flame retarding protein-based matrices, the use of additives thermally doped into biochar is recommended to both simultaneously improve fire-resistance and conserve mechanical strength. • Lanosol, a naturally occurring fire retardant, was doped into biochar pores using three methods. • The methods applied were dry mixing, chemical, and thermal doping. • The doped biochars were successfully used to fabricate wheat gluten-based biocomposites. • The most effective impregnation method was thermal doping. • Thermal doping was the best at preserving strength and lowering flammability. [ABSTRACT FROM AUTHOR]

[Display omitted] • A formaldehyde-free and effective flame-retardant coating is developed for EPS foams. • The coating can tightly bind the EPS beads, leading to enhanced mechanical strength and durable thermal insulation. • The resultant EPS composite shows excellent flame-retardant and smoke-suppressant performances. • The flame-retardant and smoke-suppressant mechanism is investigated in detail. Expandable polystyrene (EPS) foam, one of the most widely used thermal insulation of building materials, is highly flammable, while its traditional flame-retardant coating has been severely restricted by the low efficiency and the use of toxic formaldehyde adhesive. Herein, we demonstrate a formaldehyde-free phosphorus-containing polysiloxane coating that acts as both an adhesive and a flame retardant for EPS foams. In this design, on one hand, the high adhesion of the polysiloxane can evenly and tightly bind the EPS beads and expandable graphite (EG, a flame-retardant synergist filler) at a relatively low additive loading, thus leading to durable thermal insulation even under high humidity conditions. On the other hand, the functional coating can promote the formation of P/Si-containing graphited char layers during the combustion of the EPS composite, which can effectively isolate oxygen, heat, combustible compounds, and smoke particles. As a result, the EPS composite showed excellent flame retardancy with a high limiting oxygen index of 36%, a UL-94V-0 rating, and a significantly reduced peak heat release rate (−76%), while the smoke release can be greatly suppressed both in cone calorimetry and smoke density tests. This work provides a new strategy for the design of environmentally friendly coatings, which can give EPS foam high fire safety and excellent comprehensive performance. [ABSTRACT FROM AUTHOR]

Aluminum diethylphosphinate (ADP) was surface modified with the silane coupling agent KH-560, and mixed intumescent flame retardants (IFRs) were prepared with neopentyl glycol (NPG) and melamine (MEL). Then mixed IFRs and zinc borate (ZB) were compounded and added into linear low-density polyethylene (LLDPE) material. The morphology, composition, and structure of LLDPE/IFRs/ZB composites were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy. The maximum limiting oxygen index of LLDPE/IFRs/ZB composites is 28.7%, and the combustion grade is V 0. The thermogravimetric analysis results showed that the thermal degradation rate of LLDPE/IFRs/ZB composites decreased, and the carbon residue reached 15.3 wt% at 700 ℃. The cone calorimeter test showed that peak heat release rate (PHRR), total heat release rate (THR), peak smoke release rate (PSPR), and total flue gas output (TSP) of LLDPE/IFRs/ZB composites decreased by 52.5%, 24.7%, 30%, and 15.5%, respectively, compared with pure LLDPE, significantly improving the flame retardant and smoke suppression performances of LLDPE. The residual carbon analysis shows that the C C and P O C bonds in the modified mixed IFR strengthen the carbon layer structure and form a denser intumescent carbon layer, effectively hindering flame propagation. The experimental results show that the new intumescent flame retardant is a remarkable breakthrough in both flame retardancy and smoke suppression compared with ordinary intumescent flame retardants, and is more suitable for flame retardant polymer materials than traditional intumescent flame retardants. [Display omitted] • A new substance ADP@KH-560 was synthesized by surface modification of ADP with silane coupling agent. • A new mixed intumescent flame retardant was prepared with ADP@KH-560, neopentyl glycol (NPG) and melamine (MEL). • The new mixed intumescent flame retardant was compounded with zinc borate (ZB). • The new mixed intumescent flame retardant has remarkable flame retardant and smoke suppression effect. [ABSTRACT FROM AUTHOR]

Flame retardant nylon/cotton blend fabrics are widely used in the fields of industrial and military protective uniforms. In this research, we investigate the heat release properties and flammability of the 50/50 nylon/cotton blend fabric treated with a self-crosslinkable durable organophosphorus flame retardant system. For the nylon/cotton blend fabric without treatment, the blend has lower total heat release and higher percent char yield than the arithmetic sum of those of cotton and nylon as single fibers. In addition, both the peak heat release rate (PHHR) and the temperature at peak heat release ( T PHRR ) for cotton increases whereas both PHRR and T PHRR decrease for nylon when those two fibers are blended to form a fabric. Thus, the data indicated that interaction takes place between cotton and nylon during the decomposition process of the blend. The presence of the organophosphorus flame retardant system reduces PHRR, T PHRR and increase char formation for both cotton and nylon as single fibers. When the cotton and nylon are blended and then treated with the flame retardant, the PHRR of the blend becomes even lower and the percent char yield of the blend becomes even higher than those of the treated cotton and nylon as single-fiber fabric. The char length for the treated blend decreases compared with that of the treated cotton and nylon as single-fiber fabrics. We conclude that cotton and nylon interact with each other during the degradation process of the treated nylon/cotton blend fabric and such interaction reduces the flammability of the blend fabric. [ABSTRACT FROM AUTHOR]

[Display omitted] • A multifunctional smart fireproof aerogel was fabricated with polyimide and MXene. • The aerogel could trigger the fire-alarm system within 5 s when being burned. • The aerogel exhibited high fire safety and self-extinguished within 1 s. • The aerogel could monitor temperature change in real time. • The aerogel showed excellent mechanical and piezoresistive sensing performance. Multifunctional smart fire-protection aerogels are urgently needed to meet the requirement of the Internet of Everything era. Herein, we fabricated a mechanically robust and high fire-safe polyimide/MXene composite aerogel (denoted as PI@MXene) with sensitive temperature-sensing and fire-warning capability. Thanks to the unique thermoelectric effect and high electrical conductivity of the 2D transition metal carbide (MXene) nanosheet, PI@MXene exhibited a linear relationship between the thermoelectric voltage and the temperature difference, showing sensitive temperature-sensing capability. When being burned, it could repeatedly trigger the fire-warning system in less than 5 s. More importantly, owing to the lamellar barrier and skeleton supporting effect of the MXene nanosheets, PI@MXene exhibited excellent flame retardancy, which self-extinguished within 1 s after exposing to a flame for 60 s and whose peak heat release rate was significantly decreased by 78% compared with PI aerogel. Besides, PI@MXene showed impressive thermal insulation, outstanding thermostability and durable piezoresistive sensing. This work provides a novel strategy to fabricate next-generation multifunctional fireproof aerogel, showing promising applications in intelligent robots, aerospace, and railway transportation. [ABSTRACT FROM AUTHOR]

The aggregation and plasticizing of most 9,10-dihydro-9-oxa-10-phosphaphenanthrene −10-oxide (DOPO) derived additives often result in deteriorating the glass transition temperature and mechanical properties of epoxy resins (EP). To address this issue, an imide-DOPO derivative (BMP) with bulky aromatic structure was successfully synthesized. Benefitting from the space hindering and intermolecular interaction (π-π stacking) of BMP, it does not lead to the loss of glass transition temperature, and only a minor damage of tensile and impact strengths is caused. Additionally, with only 0.78 wt% loading of phosphorus (10 wt% BMP), the EP/BMP 10% achieves UL-94 V-0 and high LOI value of 35%. Simultaneously, both the heat release rate and total smoke production are markedly reduced. More excitingly, BMP exhibits aggregation-induced emission enhancement of fluorescence in the N, N -dimethylformamide/water mixed solution as well as epoxy resin. This work provides a new insight in simultaneously imparting flame retardancy and fluorescence to epoxy resins without losing glass transition temperature. [Display omitted] • Imide-DOPO derivative exhibits aggregation-induced emission enhancement. • Imide-DOPO derivative endows epoxy resin with excellent flame retardancy. • No loss of T g while the improvement of flame retardancy. • Fluorescence is imparted to the flame retardant epoxy resin. [ABSTRACT FROM AUTHOR]

• A novel crosslinkable additive flame retardant was prepared by a facial routine. • A better performance was showed comparing with traditional flame retardant. • A leap in flame-retardant properties was presented after crosslinking. With great chemical and physical properties, epoxy resins (EPs) are used almost everywhere in life and engineering, but poor flame-retardant performance hinders them for a wider use. Traditional flame retardants (the most commonly used and researched) usually have dispersion and migration problems (additive ones) or are difficult to synthesize (reactive ones). Herein, a facile crosslinking strategy is used to make traditional additive flame retardants exhibit much better properties. Firstly, a nitrogen/phosphorus containing additive flame retardant with nitrile groups is designed, successfully synthesized, and directly mixed with EP matrix, the secondary crosslinking reaction of nitrile groups inner the flame retardants will occur in cured EP thermosets which was driven by a facile thermal treatment procedure. Then the properties of the flame retardant mixed and crosslinked EP composites are measured by limiting oxygen index (LOI) test, thermogravimetric analyses (TG), UL-94 vertical burning tests, dynamic mechanical analysis and cone calorimeter test, the results show that the crosslink of the additive flame retardant greatly improved the flame-retardant properties, and with 20 wt% loading content of the crosslinked flame retardant, the LOI value reach 46.2% and the peak heat release rate decreases for 77.4% compared with neat EP, furthermore the heat resistance and dynamic mechanical property of the crosslinked samples also get promoted compared with the physical mixed ones. [ABSTRACT FROM AUTHOR]

[Display omitted] • A multifunctional MXene-based hybrid (Zr-MXene) has been prepared. • 1 wt% of Zr-MXene increases ductility and toughness of TPU by 33% and 88%, respectively. • 1 wt% of Zr-MXene increases the tensile strength and fatigue resistance of TPU. • The addition of Zr-MXene significantly reduce the flammability of TPU. • The peak heat release rate and peak smoke production rate are respectively reduced by 63% and 56%. Thermoplastic polyurethane (TPU) features many important industrial applications, but intrinsic flammability extremely impedes its practical applications. Current fire-retardant strategies often lead to improved flame retardancy but reduced mechanical properties (strength, ductility, and toughness). Hence, to date it has been unsuccessful to design advanced TPU materials that are strong, stretchable, tough, fatigue-and fire-resistant to meet increasing performance portfolio requirements. Here, we report a hybridized fire retardant (Zr-MXene) by in situ facilely loading zirconium amino-tris-(methylenephosphonate) (Zr-AMP) onto the titanium carbide (MXene) surface. Our results show that with 1 wt% of Zr-MXene, the resultant TPU nanocomposites demonstrate a record break strain (2060%) and toughness (316 MJ/m3) to date, in addition to increased tensile strength by 43.4% and improved fatigue resistance relative to the TPU matrix, because of favorable interfacial hydrogen-bonding. Moreover, the resultant TPU material exhibit significantly reduced flammability as a result of the combined physical barrier, catalytical carbonization and diluting effects of Zr-MXene. This work provides a promising strategy for the creation of multifunctional MXene and its polymeric nanocomposites, which hold great promise for many industrial applications. [ABSTRACT FROM AUTHOR]

Epoxy resins (EPs) are a kind of widely used engineering materials, because of their excellent mechanical, chemical and physical properties, but a severe problem they faced is their poor flame retardancy. Single molecule flame retardants have met the bottleneck after the massive researches of the past decade, so, with the development of the polymer technology, hyperbranched flame retardants have been researched and applied, owing to their better and more efficient flame retardancy. Herein, a facile thermal treating procedure was applied to the cured EP thermosets which contained a crosslinkable additive flame retardant to in-situ form a hyperbranched flame retardant. The single molecule flame retardants with N/P elements and crosslinkable nitrile groups were synthesized through an easy method, and physically mixed with EP matrix. After the curing reaction of EP matrix, the thermosets were further treated with a thermal treating procedure, while transferring the single molecule flame retardant into hyperbranched flame retardant, the semi-interpenetrating network was formed at the same time. The flame-retardant properties have been measured by limiting oxygen index (LOI) tests, UL-94 vertical burning tests and cone calorimeter tests, the results showed the flame retardants were extremely efficient and greatly elevated the flame retardancy of EPs, since the 0.5 wt% content could make modified EP samples pass the UL-94 V-0 rate, and with 20 wt% content the LOI value reached 49.5 % and the peak heat release rate reduced for 71.6 % compared with pure EPs. [ABSTRACT FROM AUTHOR]

Shou sugi ban, also known as yakisugi, or just sugi ban, is an aesthetic wood surface treatment that involves charring the surface of dimensional lumber, such as exterior cladding. The goal of this research is to examine the effect of shou sugi ban on the flammability and decay resistance of wood. Several species and variants of commercially available sugi ban were tested. The flammability was examined from the heat release rate curves using the oxygen consumption method and cone calorimeter. Durability was examined with a soil block assay for one white-rot fungus and one brown-rot fungus. The testing showed that the shou sugi ban process did not systematically improve the flammability or durability of the siding. [ABSTRACT FROM AUTHOR]

Lyocell fabrics are widely applied in textiles, however, its high flammability increases the risk of fire. Therefore, to resolve the issue, a novel biomass-based flame retardant with phosphorus and nitrogen elements was designed and synthesized by the reaction of arginine with phosphoric acid and urea. It was then grafted onto the lyocell fabric by a dip-dry-cure technique to prepare durable flame-retardant lyocell fabric (FR-lyocell). X-ray photoelectron spectroscopy (XPS) and Fourier-transform infrared spectroscopy (FTIR) analysis demonstrated that the flame retardant was successfully introduced into the lyocell sample. Thermogravimetric (TG) and Raman analyses confirmed that the modified lyocell fabric featured excellent thermal stability and significantly increased char residue. Vertical combustion results indicated that FR-lyocell before and after washing formed a complete and dense char layer. Thermogravimetric Fourier-transform infrared (TG-FTIR) analysis suggested that incombustible substances (such as H2O and CO2) were produced and played a significant fire retarding role in the gas phase. The cone calorimeter test corroborated that the peak of heat release rate (PHRR) and total heat release (THR) declined by 89.4% and 56.4%, respectively. These results indicated that the flame retardancy of the lyocell fabric was observably ameliorated. [ABSTRACT FROM AUTHOR]

Viscoelastic polyurethane (VEPUR) foams with increased thermal resistance are presented in this article. VEPUR foams were manufactured with the use of various types of flame retardant additives and keratin fibers. The structure of the modified foams was determined by spectrophotometric-(FTIR), thermal-(DSC), and thermogravimetric (TGA) analyses as well as by scanning electron microscopy (SEM). We also assessed the fire resistance, hardness, and comfort coefficient (SAG factor). It was found that the use of keratin filler and flame retardant additives changed the foams' structure and properties as well as their burning behavior. The highest fire resistance was achieved for foams containing keratin and expanding graphite, for which the reduction in heat release rate (HRR) compared to VEPUR foams reached 75%. [ABSTRACT FROM AUTHOR]

In this study, a representative set of thermally thin materials including various lignocellulosic and synthetic fabrics, dense wood, and polypropylene sheets were tested using a cone calorimeter at different heat fluxes. Time-to-ignition, critical heat flux, and peak of heat release rate (pHRR) were the main parameters considered. It appears that the flammability is firstly monitored by the sample weight. Especially, while the burning rate of thermally-thin materials does never reach a steady state in cone calorimeter, their pHRR appears to be mainly driven by the fire load (i.e., the product of sample weight and effective heat of combustion) with no or negligible influence of textile structure. A simple phenomenological model was proposed to calculate the pHRR taking into account only three parameters, namely heat flux, sample weight, and effective heat of combustion. The model allows predicting easily the peak of heat release rate, which is often considered as the main single property informing about the fire hazard. It also allows drawing some conclusions about the flame retardant strategies to reduce the pHRR.. [ABSTRACT FROM AUTHOR]

Wildfires and pests are natural disturbance agents in many forest ecosystems that often contribute to ecological succession, nutrient cycling, and forest species composition. Mongolian pine (Pinus sylvestris var. mongolica) is a coniferous species that plays an important role as an ecological barrier, and is widely spread in northern China. Its wood is loose; its branches, leaves, and cones contain a high level of resin and volatile oils that make the species highly flammable and the stands dominated by the species are very vulnerable to fire. Recently, resinosis on boles of Pinus sylvestris became an epidemic in China. To explore the potential effects of pests on fire, we compared the flammability of Mongolian pine barks with or without resinosis on boles using a cone calorimeter and several combustion analyses. We found that the barks from boles with resinosis had a greater oil content than the healthy trees. The study also indicated that the ignition times of the barks from boles with and without resinosis were 6.00 s (±1.73) and 22.67 s (±1.15), respectively, and that the heat release rate curves were parabolic, with peaks 225.19 and 75.27 kW/m2, respectively, for the two bark types. Additionally, because resinosis was on the low- to mid-bole of infested trees, the barks from boles with resinosis tended to be ignited much easier than those without resinosis. This clearly evidenced that pests could affect fire severity and behavior by increasing forest flammability. More information about the role that pests play in the different forest cover types is needed to increase our understanding of fire danger and to develop sound forest management policies. [ABSTRACT FROM AUTHOR]

We aimed to study the impact of surface modification of basalt fiber (BF) on the mechanical properties of basalt fiber-based epoxy composites. Four different types of pretreatment approaches to BF were used; then a silane coupling agent (KH550) was applied to further modify the pretreated BF, prior to the preparation of epoxy resin (EP)/BF composites. The combination of acetone (pre-treatment) and KH550 (formal surface treatment) for basalt fiber (BT-AT) imparted the EP/BF composite with the best performance in both tensile and impact strengths. Subsequently, such modified BF was introduced into the flame-retardant epoxy composites (EP/AP750) to prepare basalt fiber reinforced flame-retardant epoxy composite (EP/AP750/BF-AT). The fire behaviors of the composites were evaluated by vertical burning test (UL-94), limiting oxygen index (LOI) test and cone calorimetry. In comparison to the flame-retardant properties of EP/AP750, the incorporation of BF-AT slightly reduced LOI value from 26.3% to 25.1%, maintained the good performance in vertical burning test, but increased the peak of the heat release rate. Besides, the thermal properties and mechanical properties of the composites were investigated by thermogravimetric analysis (TGA), universal tensile test, impact test and dynamic mechanical analysis (DMA). [ABSTRACT FROM AUTHOR]

The demand for eco-friendly poly (lactic acid) (PLA) nonwovens grows at a high rate in the past several decades, however, only a little attention has been received for flame retardant PLA nonwoven fabrics. In this work, a novel halogen-free self-intumescent polyelectrolyte tris (hydroxymethyl)-aminomethane polyphosphate (APTris) was synthesized by reacting ammonium polyphosphate with tris (hydroxymethyl) aminomethane, and was then used to improve the fire resistance of PLA nonwovens via a dip-nip process. The flammability characterization indicated the limiting oxygen index value was increased to 30.0% from 18.3%, and the damaged area in the vertical burning test was reduced by about 87.0% by the presence of APTris. The cone calorimeter test results revealed that the peak heat release rate and total heat release of the treated sample were decreased by 41.0% and 28.2% respectively compared with that of the control PLA nonwoven sample. The char residue was increased to 12.3 from 1.7 wt % at 800 °C. It is suggested that the dense char barrier formed at the presence of APTris prevents heat, smoke, and gas transfer, and hence enhance thermal dilatability and flame retardancy of PLA nonwovens. This simple sustainable halogen-free treatment has great potential to produce cleaner commercialized flame-retardant PLA nonwovens. Image 1 • An intumescent polyelectrolyte (APTris) was prepared by ion exchange reaction. • The APTris significantly improved the flame retardancy of PLA nonwovens. • The molten droplet of treated PLA nonwovens was reduced. • The APTris was carbonized to form compact protective layer during combustion. [ABSTRACT FROM AUTHOR]

This work presents the cell structure and selected properties of polyurethane (PUR) foams, based on two types of hydroxylated used cooking oil and additionally modified with three different flame retardants. Bio-polyols from municipal waste oil with different chemical structures were obtained by transesterification with triethanolamine (UCO_TEA) and diethylene glycol (UCO_DEG). Next, these bio-polyols were used to prepare open-cell polyurethane foams of very low apparent densities for thermal insulation applications. In order to obtain foams with reduced flammability, the PUR systems were modified with different amounts (10–30 parts per hundred polyol by weight—php) of flame retardants: TCPP (tris(1-chloro-2-propyl)phosphate), TEP (triethyl phosphate), and DMPP (dimethyl propylphosphonate). The flame retardants caused a decrease of the PUR formulations reactivity. The apparent densities of all the foams were comparable in the range 12–15 kg/m3. The lowest coefficients of thermal conductivity were measured for the open-cell PUR foams modified with DMPP. The lowest values of heat release rate were found for the foams based on the UCO_TEA and UCO_DEG bio-polyols that were modified with 30 php of DMPP. [ABSTRACT FROM AUTHOR]

In this manuscript, the Layer-by-Layer technique is used to modify the surface of flax fabrics using a quad-layer architecture (QL) prior to their assembly in polylactic acid biocomposites. The aim is to produce nanostructured interphases capable of conferring flame retardancy while maintaining mechanical properties. Only 2.5 QL significantly improve the flame retardancy and fire safety of the prepared composites as demonstrated by LOI values of 25.3%, considerably reduced flame spread rates and the substantial reduction in peak of heat release rate (−33%) and maximum average rate of heat emission (−30%) during cone calorimetry. Mechanical testing showed improved modulus and limited reductions in flexural strength. These results make the approach developed in this manuscript very attractive in the design of advanced biocomposites with optimized fire retardancy and mechanical properties. Image 1 • Layer-by-Layer nanostructured interphases are employed for biocomposites • Flame retardant confinement at the interphase avoids matrix degradation • Improved mechanical and flame retardant properties can be simultaneously achieved [ABSTRACT FROM AUTHOR]

The inflammability of asphalt road will promote fire spread in the tunnel and produce lots of toxic smoke. To improve the fire resistance of asphalt pavement, mineral powder flame retardants are generally replaced by flame retardants in equal amounts. In this study, the effects of the synergistic flame retardancy system of halloysite nanotubes (HNTs) and conventional flame retardants (CFR) on the flame retardancy performance and mechanism of asphalt were investigated. Firstly, the flame retardancy properties of the HNTs and CFR composite modified asphalt were investigated based on the Cleveland open cup method (COC), Limiting oxygen index meter (LOI), and Cone calorimeter tests (CCTs). Then, the flame retardancy mechanism of the modified asphalt was studied based on Thermogravimetric analyzer (TGA), Fourier-transform infrared (FTIR), and Scanning electron microscopy (SEM). The results show that adding HNTs could improve the flame retardancy of the CFR modified asphalt binder. When 1 wt % HNTs and 8 wt % CFR were used, the limiting oxygen index of asphalt increased by 40.1%, the ignition temperature increased by 40 °C, while the heat release rate, total heat release, the smoke production rate, total smoke release, and other parameters decreased with varying degrees. Based on TG, FTIR, and SEM, the targeted flame retardancy mechanism and synergistic effect of HNTs/CFR flame retardancy system were revealed and summarized as three stages: (1) Stage 1, aluminum hydroxide (ATH) absorbs heat through thermal decomposition and inhibits the decomposition of lightweight components in asphalt; (2) Stage 2, aluminum diethyl phosphate (ADP) decomposes and produces organic phosphoric acid, which catalyzes crosslinking and ring thickening of asphalt and the quenching effect of phosphorus free radicals to block the combustion; and (3) Stage 3, HNTs plays an important role in increasing the integrity and density of the barrier layer. In addition, the Al2O3 produced by the decomposition of ATH, the carbon layer formed by the ADP catalyzed pitch, and HNTs play a significant synergistic effect in the formation of the barrier layer. Thus, the combination of HNTs and CFR has been proved to be a prospective flame retardancy system for asphalt. [ABSTRACT FROM AUTHOR]

Ethylenediamine modified ammonium polyphosphate (EDA-MAPP) and charring-foaming agents (CFA) were prepared using a simple chemical method and further used to make intumescent flame retardant coatings based on epoxy resin. The content of MAPP and CFA was fixed at a ratio of 2:1. Nanoparticles of magnesium aluminate (MgAl2O4 NPs) have been introduced into the flame retardant coating formulation in various quantities to evaluate the promotional action of MgAl2O4 NPs with a flame retardant coating system. The promotional action of MgAl2O4 NPs on the flame retardant coating formulation was studied using a vertical burning test (UL-94V), limiting oxygen index (LOI), thermogravimetric analysis (TGA) and Fourier transform infra-red spectroscopy (FTIR). The UL-94V results indicated that the addition of MgAl2O4 effectively increased flame retardancy and met the V-0 rating at each concentration. The TGA results revealed that the incorporation of MgAl2O4 NPs at each concentration effectively increased the thermal stability of the flame retardant coating system. Cone-calorimeter experiments show that MgAl2O4 NPs effectively decreased peak heat release rate (PHRR) and total heat release (THR). The FTIR results indicated that MgAl2O4 NPs can react with MAPP and generate a dense char layer that prevents the transfer of oxygen and heat. [ABSTRACT FROM AUTHOR]

Even though casein has an intrinsic potential ability to act as a flame retardant (FR) additive, the research regarding the FR performance of casein filled polymeric composites has not been thoroughly conducted. In the present work, two commercial casein products, such as lactic casein 720 (LAC) and sodium casein 180 (SC), were chosen to investigate their effects on the performances of the polypropylene (PP) composites. The melt compounding and compression moulding processes were employed to fabricate these casein-based composites. Ammonium polyphosphate (APP) was also selected to explore its combined effects in conjunction with casein on the composite's flammability. The cone calorimeter results showed that the addition of casein significantly reduced (66%) the peak heat release rate (PHRR) of the composite compared to that of neat PP. In particular, the combination of LAC and APP led to the formation of more compact and rigid char compared to that for SC based sample; hence, a further reduction (80%) in PHRR and self-extinguishment under a vertical burn test were accomplished. Moreover, the tensile modulus of the composite improved (23%) by the combined effects of LAC and APP. The overall research outcome has established the potential of casein as a natural protein FR reducing a polymer's flammability. [ABSTRACT FROM AUTHOR]

While environmental concerns have caused polymeric brominated primary flame retardants (PolyBrFRs) to be effective replacement monomeric species, few alternatives for antimony trioxide (ATO) have been developed beyond the zinc stannates (ZnSs). Previous research, which explored the interactions of aluminium (AlW), tin (II) (SnW) and zinc (ZnW) tungstates with several phosphorus-containing flame retardants in polyamide 6.6 (PA66), is extended to two PolyBrFRs: brominated polystyrene (BrPS), and poly(pentabromobenzyl acrylate) (BrPBz). On assessing the effect of each tungstate on the thermal degradation and flammability in combination with each PolyBrFR using TGA, UL94, LOI, cone calorimetry and TGA-FTIR, only ZnW and SnW showed significant increases in LOI (>26 vol.%). Both ZnW-BrPS- and ZnW-BrPBz-containing formulations yielded average UL94 ratings ≥ V-2 and TGA char residues (corrected for metals content at 500 °C) in air > 15 wt.%. BrPS-containing samples, especially those containing ZnW and SnW, generated peak heat release rates approximately 50% lower than the equivalent BrPBz samples. These reductions did not correlate with respective increases in LOI, suggesting that tungstate-PolyBrFR combinations influence pre-ignition differently to post-ignition behaviour. Calculated synergistic effectivities indicate that ZnW functions as a synergist in both pre- and post-ignition stages, especially with BrPS. TGA-FTIR and char analyses showed that, in addition to the vapour-phase activity normally associated with PolyBrFRs, condensed-phase processes occurred, especially for the ZnW-PolyBrFR combinations. Additionally, ZnW demonstrated significant smoke-suppressing properties comparable with zinc stannate (ZnS). [ABSTRACT FROM AUTHOR]

The flammability of tropical woods and the effect of a selected fire protection coating were evaluated using a cone calorimeter at a cone radiancy of 35 kW/m2. Three samples were from the South American continent (Cumaru, Garapa, Ipe), and two were from the Asian continent (Kempas and Merbau). Samples were treated with commercial fire retardant (FR) containing ferrous phosphate as an essential component. The untreated samples were used as reference materials that were of particular interest concerning their flammability. It was shown that there is unambiguous correlation between the effective heat of combustion (EHC) and total oxygen consumed (TOC) related to mass lost during burning for both the untreated and treated samples. In the case of Cumaru and Garapa, there exists an inverse relation between the amount of smoke and carbon residue. The decisive effect on the time of ignition was performed by the initial mass of the sample. This is valid for the spruce and the Cumaru, Ipe, and Kempas, both treated and untreated with retardant, while Garapa and Merbau were found to decline. According to the lower maximum average rate of heat emission (MARHE) parameter, a lower flammability was observed for the treated samples of wood, except for Garapa wood. Fire-retardant treated Garapa and Merbau also have a significantly lower time to ignition than untreated ones. [ABSTRACT FROM AUTHOR]

Shape-stabilized phase change material (SSPCM) is a promising thermal energy storage material in energy-saving buildings. However, its flammability leads to a fire risk. The conventional bulk addition method has a limited flame-retardant effect. Herein, a series of surface coatings with various flame retardants were introduced to improve flame retardance of SSPCM. The results showed that all of the coatings had flame-retardant effects on SSPCM; In particular, the EG coating performed the best: the horizontal burning time was the longest, the limiting oxygen index was above 30%, the V0 classification was obtained, the peak heat release rate was sharply decreased from 1137.0 to 392.5 kW/m2 and the burning process was prolonged with the least total smoke production. The flame-retardant mechanism was discussed. As paraffin easily evaporated from the SSPCM at a moderate temperature, it caused flames. After being surface coated, the EG-based coatings first hindered the volatilization of paraffin at a moderate temperature, then expanded and formed thick porous carbon layers at a high temperature to block the transfer of combustibles, oxygen and heat between the bulk and the environment. Therefore, the surface coating strategy achieved a desirable flame-retardant level with fewer flame retardants. [ABSTRACT FROM AUTHOR]