Cone Calorimetry Test Results Research Articles

Preparation and properties of multilayer core-shell structure ammonium polyphosphate synergistic with THEIC for flame retardant LDPE

In this paper, a new type of highly efficient intumescent flame-retardant low-density polyethylene composite was prepared using two key technologies, namely, microencapsulation encapsulation technology and novel carbon formation technology. Precisely, β-cyclodextrin encapsulated modified ammonium polyphosphate@melamine formaldehyde resin (β-CDMCAPP@MF) was prepared by using Si-IFR synergistic flame retardant effect combined with the gel-solution method, and then flame retardant low-density polyethylene (LDPE) was prepared by compounding with tris-(2-hydroxyethyl) isocyanate (THEIC). The results showed that β-CDMCAPP@MF was modified with MF, β-CD, and silica coating. This modification resulted in excellent hydrophobicity and good compatibility with LDPE. The addition of IFR containing β-CDMCAPP@MF significantly improved the flame retardancy of the LDPE composites. Specifically, when 30 wt% of β-CDMCAPP@MF was added, the ultimate oxygen index of the composites reached 24.7 %, and V-0 grade and the tensile strength went 11.41 MPa. Compared with IFR/LDPE with the same proportion of MF@MCAPP and β-CD@MCAPP, the ultimate oxygen indices were increased by 9.72 % and 12.15 %, respectively. The introduction of THEIC into the flame retardant system resulted in a LOI value of 36.5 % and an FRI value of 2.523, which is 32.33 % higher than that of the composites containing 30 wt% of the flame retardant system (without THEIC). Cone calorimetry test results showed that introducing β-CDMCAPP@MF and THEIC significantly improved the smoke emission.

Peacock flaunting tail inspired-multiple interactions between black phosphorene and glass powder with safety shield fire of epoxy resin

Black phosphorene (BP) has caused widespread attention for excellent dimension effects and thermal stability. Herein, glass powder (GP), a waste from ceramic production, is blended with black phosphorene (GBP) for reducing the fire hazard of epoxy resin (EP) matrix. Density functional theory (DFT) reveals that the adsorption energy between BP and SiO2 and Al2O3 are −3.55 and −4.27 eV, respectively, indicating a strong interaction between BP and GP. The results of cone calorimetry test (CCT) indicate that the flame retardant performance of EP can tremendously promote through adding 1.5 wt% GBP nanosheets, for instance, the peak heat release rate (pHRR) and the total heat release (THR) are decreased by 27.76 % and 31.42 %, respectively. Epoxy composites with only 1.5 wt% GBP nanosheets can reach UL-94 V-0 rating level with a limit oxygen index (LOI) of 29.7. These positive results are attributed to the collaborative function of physical obstacle, free radicals capturing and catalytic char formation between BP and GP components. In addition, the thermal conductivity decreased by 8.91 %, and the tensile strength increased by 39.99 % with the 1.5 wt% addition amount of GBP nanosheets. This work has a promising foreground for exploiting the resue of waste to satisfy the requirement of sustainable practical applications.

The synergistic flame retardant effect of biobased phytic acid arginine salt and hydroxylated montmorillonite in polybutylenes succinate

In this research, hydroxylated nano montmorillonite (DK2) was used as a synergistic agent in combination with phytic acid arginine salt (PaArg). The flame retardancy and mechanical properties of PBS with different amounts of PaArg and DK2 were studied. Furthermore, the synergistic effect and mechanism of PaArg and DK2 in PBS were explored. The results showed that adding 23.5 % PaArg and 1.5 % DK2 increased the limiting oxygen index value (LOI) of the composite to 31.4 %, passing the UL 94 V-0 rating. By adding 25 % PaArg alone, the LOI value of the composite is 26.2 %, and the vertical burning test result is only V-2 rating. The cone calorimetry test results show that the peak heat release rate, total heat release rate, and total smoke production of PBS/23.5 % PaArg/1.5 % DK2 composite are 55.8 %, 17.1 %, and 44.7 % lower than those of PBS/25 % PaArg composite, respectively. All the results showed that PaArg and DK2 exhibited good synergistic flame retardancy in PBS. In addition, the impact strength and bending strength test results show that the impact strength and bending strength of PBS/23.5 %PaArg/1.5 %DK2 composite are higher than those of PBS/25%PaArg composite. This work improved the flame retardant efficiency of biobased flame retardants in PBS.

Hierarchical NiO/Al2O3 nanostructure for highly effective smoke and toxic gases suppression of polymer Materials: Experimental and theoretical investigation

There is still a lack of in-depth investigation of the suppression mechanism for polymeric materials. Herein, based on the density functional theory (DFT) study, the flame retardancy, smoke, and toxic gases suppression mechanisms of hierarchical NiO/Al2O3 nanostructures in thermoplastic polyurethane (TPU) are in-depth revealed. The incorporation of NiO/Al2O3-S into TPU leads to a significant reduction in total smoke release by 41.9%, and peak CO production rate by 47.8% (Cone calorimetry test results). Besides, the NiO/Al2O3-S results in a remarkable decrease of 48% in Dsmax during the smoke density test. Most importantly, based on DFT calculations, incorporating catalysts enhances the adsorption energy of CO, O2, and CO2 on the surface of TPU nanocomposites, thereby facilitating CO oxidation reactions. This is conducive to reducing flue gas emissions and toxicity levels. This work introduces DFT into the flame retardancy research of polymer materials, thus providing reliable guidance for designing highly effective smoke suppressants.

Flame retardancy and smoke suppression effect of an organic–inorganic hybrid containing phosphaphenanthrene‐modified magnesium hydroxide/zinc borate on epoxy resin

AbstractTo improve the flame retardancy and smoke suppression effect of epoxy resin (EP), a new organic–inorganic hybrid (MH@ZB‐ODOPB) was fabricated. First, hierarchical‐structured particles (MH@ZB) were prepared by gradually depositing zinc borate (ZB) on the surface of magnesium hydroxide (MH) via a heterogeneous deposition process. Second, MH@ZB was modified with 10‐(2,5‐dihydroxyphenyl)‐10‐hydro‐9‐oxa‐10‐phospha‐phenanthrene‐10‐oxide (ODOPB) to obtain MH@ZB‐ODOPB. Finally, the chemical structure and form of MH@ZB‐ODOPB were analyzed via X‐ray diffraction, Fourier transform infrared spectroscopy, X‐ray photoelectron spectroscopy, and scanning electron microscopy. The characterization results show that ZB was loaded onto the surface of MH, and ODOPB was grafted on the surface of MH@ZB. The cone calorimetry test results show that when 7.5 wt% MH@ZB‐ODOPB was added into EP, the peak heat release rates, total heat release, total smoke production, and peak smoke production rates decreased by 51.8%, 42.4%, 58.1%, and 66.1%, respectively. Moreover, EP/MH@ZB‐ODOPB exhibited a limiting oxygen index of 33%. These results show that the incorporation of MH@ZB‐ODOPB into EP composites considerably improved the flame retardancy and smoke suppression properties of EP composites. The double action of MH@ZB‐ODOPB in condensed and gas phases was investigated by analyzing the carbon residue and pyrolysis gas. Furthermore, the implementation of ODOPB improves the mechanical properties of EP composites.

Alloying synergistic flame retardant effect improving fire resistance and mechanical properties of polyamide 6

AbstractThe alloying synergistic flame retardant effect was studied by using polyetherimide (PEI) and aluminum diethylphosphinate (ADP) for polyamide 6 (PA6), which can endow PA6 composites with excellent mechanical properties and flame retardancy simultaneously. On the one hand, because the molecular structures of PEI and PA6 are similar, adding PEI with PA6 can form PEI‐PA6 alloy by the hydrogen bond effect and nice homogeneous phase, which can endow PA6 composites with excellent mechanical properties. On the other hand, the test results of flame retardancy show that 9ADP/10PEI‐PA6 composite can obtain higher LOI value (LOI = 31%), and excellent flame retardant rating (UL94 V‐0) with 9%ADP and 10%PEI. From the results of cone calorimetry test, the pk‐HRR and THR of 9ADP/10PEI‐PA6 are reduced by 24.4% and 24.7%, respectively, compared to PA6, and higher char residue rate was obtained, which shows that ADP combined with PEI‐PA6 alloying exerts an excellent flame retardant synergistic effect. Through the study of flame retardant mechanism found that ADP works together with PEI can effectively increase the quenching effect in the gas phase, promote thermal stability, and delay the decomposition process of PA6 matrix during the combustion process. Meanwhile, it also increases the char yield to exert a synergistic effect in the condensed phase by ADP/PEI‐PA6. The residual char rate reached 36.6%, higher than neat PA6 about 4.6 wt.%. Thus, the alloying flame retardant method using ADP/PEI‐PA6 can endow PA6 with better flame retardancy and more excellent mechanical properties. Importantly, it provides a new direction for developing high‐performance halogen‐free flame retardant materials.

An eco-friendly and intumescent P/N/S-containing flame retardant coating for polyamide 6 fabric

This study focused on the construction of an eco-friendly and intumescent flame retardant (FR) coating for polyamide 6 (PA6) fabric. The intumescent FR coating, consisting of phytic acid, pentaerythritol and thiourea, was deposited onto PA6 fabric through dip-coating technique. The FR performance, anti-dripping ability, thermal stability, combustion behavior and mechanical property of the coated PA6 fabrics were explored. The severe dripping of coated PA6 fabric was totally eliminated, achieving an excellent FR performance at a low P (2.2%) and S (3.4%) content. Correspondingly, the LOI increased to 28.8% versus 23.2% of pristine one, displaying good flame retardancy. The char residue analyses confirmed the intumescent FR behavior of coated PA6 fabrics. The intumescent char layer played a major role in isolating the exchange of combustibles, oxygen and heat, leading to the significant reduction in heat release performance. The results of cone calorimetry test showed that the peak heat release rate and average effective heat of combustion of coated PA6 fabric decreased by about 36.5% and 34.4%, respectively versus pristine one. Meanwhile, the sulfur-based gases captured free radicals to interrupt the continuous combustion, leading to the significantly improved flame retardancy. Furthermore, the FR coating exerted little influence on the mechanical performance of PA6 fabric.

Assembling MXene with bio-phytic acid: Improving the fire safety and comprehensive properties of epoxy resin

Phytic acid (PA)-modified MXene (P-MXene) was prepared combination selective etching with assemble method, and was mixed with epoxy resin (EP) to investigated its flame retardancy, thermal conductivity, conductivity and mechanical properties. P-MXene exhibited two-dimensional single layer structure and had good char-forming property with 86.7% char residue at 800 °C. The cone calorimetry test results showed that P-MXene endowed EP with excellent flame retardancy. Compared with pure EP, the peak heat release rate, peak smoke release rate, peak CO generation rate, and peak CO2 generation rate of EP composites with 2 phr P-MXene decreased by 38.6%, 31.6%, 38.7% and 40.6%, respectively. The flame retardant mechanism was attributed to physical barrier, catalyzing carbonization effect, oxidative thermal degradation and physical barrier effect. Additionally, the conductivity and mechanical properties of EP composites were slightly reduced. This work provides a promising method to design multifunctional polymers.

Synergistic effects of aryl diazonium modified Few-Layer black Phosphorus/Ultrafine rare earth yttrium oxide with enhancing flame retardancy and catalytic smoke toxicity suppression of epoxy resin

Black phosphorus (BP), as a promising star of two-dimensional (2D) van der Waals family, has attracted extensive attention for its characteristic dimension effects, mechanical properties and thermal stability. Herein, we report a facile strategy of integrating aryl diazonium modified few Layer black phosphorus with loading of ultrafine yttrium oxide (BP-NH-Y), for reducing the fire hazard of epoxy resin (EP). The results of cone calorimetry test results manifest that the flame retardancy of EP can significantly improve by adding 2 wt% BP-NH-Y, for instance, the peak heat release rate (pHRR) and the total heat release (THR) is reduced by 47.0% and 48.1%, respectively. Especially, adding the BP-NH-Y nanosheets distinctly inhibite the diffusion of EP pyrolysis products (such as toxic CO, hydrocarbons etc.) during flaming. In particular, epoxy composites with only 1.0 wt% BP-NH-Y were able to achieve UL-94 V-0 rating with an oxygen index of more than 30. This work may have a promising prospect for developing efficient covalent functionalized BP nanosheets to meet the needs of sustainable applications.

The preparation of ionic liquid doped graphene composite and its synergistic flame retardant effect with hexaphenoxy cyclotriphosphazene on epoxy resin

<p indent=0mm>In this article, ionic liquid doped graphene (GnP@ILs) was successfully synthesized by green and environmentally friendly wet ball milling from expandable graphite and 1-butyl-3-methylimidazole hexafluorophosphate ionic liquid ([BMIM]PF₆), and its surface morphology, crystal structure and chemical structure were characterized. GnP@ILs alone or mixed with hexaphenoxy cyclotriphosphazene (HPCTP) was added to epoxy resin (EP) to study its effect on the comprehensive properties of EP composites. Limiting oxygen index (LOI), vertical combustion (UL-94) and cone calorimetry test results show that GnP@ILs can improve the fire resistance of EP composites, and the EP composites (EP/7.2wt%HPCTP/1.8wt%GnP@ILs) has the best flame retardant performance, with an LOI of 33.8%, and has passed the UL<sc>-94 V</sc> 0 rate. The peak heat release rate and total heat release rate of EP/7.2wt%HPCTP/1.8wt%GnP@ILs were decreased by 55.54% and 44.28%, respectively. At the same time, the addition of [BMIM]PF₆ enhanced the interface compatibility between the flame retardant and EP, and the tensile strength and impact strength of EP composites were significantly improved.

An efficient and eco‐friendly route to prepare graphene nanosheet and its effect on the flammability of polypropylene composites

AbstractA rapid, green, and cost‐effective route for the preparation of graphene nanosheets (GRNs) from their layered bulks by the ultrasonic together with mechanical grinding was reported. The whole exfoliation process of synthesizing GRNs lasted just 2 hours without involvement of any acid solvent or other organic solvents; only one kind of waste biomass as adhesive could be used. The structure and morphology of GRNs were characterized and then was then introduced into polypropylene by melt blending, and the cone calorimetry test results indicated that the presence of GRNs could enhance the flame retardancy of PP composite.

Eco-friendly flame retardant and dripping-resistant of polyester/cotton blend fabrics through layer-by-layer assembly fully bio-based chitosan/phytic acid coating

Polyester/cotton blend fabrics are widely used in clothing and household textiles which combine the comfort of cotton and excellent mechanical strength of polyester. However, their high flammability due to the special “wick effect” resulting from the different thermal decomposition process of cotton and polyester causes greatly potential fire hazards. In this study, fully bio-based intumescent flame retardant (IFR) coating of chitosan/phytic acid (CS/PA) was layer-by-layer (LBL) assembly constructed on polyester/cotton blend fabrics. The LOI value of polyester/cotton blend fabric which was LBL assembly coated by 20 bilayers CS/PA reached 29.2%. And the dripping of coated fabric was eliminated. The results of cone calorimetry test confirmed CS/PA coating greatly improved the flame retardancy of polyester/cotton blend fabrics. Thermogravimetric analysis (TGA) results showed CS/PA coating changed the thermal decomposition process to promote the char formation of polyester/cotton blend fabrics. CS/PA coating on fabric could form the IFR system which acts through both condensed phase action by the catalysis dehydration reaction to forming stable char and gas phase action by the blowing effect. This research provides a new strategy to eco-friendly flame retardant and dripping-resistant for polyester/cotton blend fabrics by bio-based IFR system through facile LBL assembly method.

Waste to resource: preparation of an efficient adsorbent and its sustainable utilization in flame retardant polyurethane composites.

In order to realize the comprehensive utilization of industrial solid waste and the treatment of water eutrophication, the flower-like magnesium hydroxide (MH) was synthesized from phosphorus tailings by sulfuric acid hydrolysis and a hydrothermal method and then was modified with a metal organic framework (MOF) to remove the phosphates enriched in water through adsorption. Both MH and MOF-modified MH (MH@MOF) presented good removal performance of phosphates. The phosphate-adsorbed composites (MH–P and MH@MOF–P) were sustainably used as effective flame retardants for thermoplastic polyurethane (TPU) at low loadings by a solution blending method. The cone calorimetry test results showed that MH@MOF–P can significantly reduce the heat release rate (HRR), smoke production rate (SPR), total smoke release (TSR), CO release rate and CO2 release rate of TPU composites, compared with those of neat TPU. The novel strategy proposed in this work is of great significance for resource recycling, environmental governance and improving fire safety of polymer materials.

Preparation of flame-retardant/dyed cotton fabrics: flame retardancy, dyeing performance and flame retardant/dyed mechanism

An environmentally friendly phosphorous-nitrogen synergistic flame retardant, 6-monochloro-1,3,5-triazine-4-p-aminobenzenesulfonate-2-methylphosphinic acid dimethyl ester (CTSGP), was synthesized and applied to improve the thermal stability of cotton fabrics. The chemical structure of GTSGP was analyzed by Fourier transform infrared spectroscopy, and the appearance of its group characteristic peaks indicated that the compound was successfully prepared. The flame retardant reacted with the hydroxyl groups of cotton fabrics to constitute covalent bonds that bunch firmly to the surface. The flame retardancy of the treated cotton fabrics was evaluated by the limiting oxygen index (LOI) and vertical flammability test. The results showed that the LOI value of cotton fabrics treated by CTSGP increased from 18.0 to 29.0%, the length of char residue was only 62 mm without after-flame time and after-glow time. The thermogravimetric and cone calorimetry test results showed that the char-forming ability of the treated cotton fabrics was significantly improved and the peak heat release rate decreased from 144.23 to 11.64 kW/m2. Besides, the mixed dyeing behavior of GTSGP and reactive dyes showed that the cotton fabrics can obtain the ideal color and flame retardant performance at the same time. The color fastness to wet rubbing of the flame-retardant/dyed fabrics reaches 4, and the softness is slightly improved compared with untreated cotton fabrics. The non-flammable nitrogen gas and organophosphate carbon layer generated by the treated cotton fabrics during combustion contribute to the flame resistance of fabrics. A reactive phosphor-nitrogen flame retardant (CTSGP) was synthesized and applied to cotton fabrics to obtain excellent flame retardant property.

Improving flame retardancy and self-cleaning performance of cotton fabric via a coating of in-situ growing layered double hydroxides (LDHs) on polydopamine

In order to improve flame retardancy and soiling resistance of cotton fabric, a safe coating was fabricated on its surface. At first dopamine was polymerized on the cotton surface to be polydopamine (PDA), and then layered double hydroxides (LDHs) grew in situ on the platform of PDA by the coordination of catechol groups and metal ions. Cone calorimetry test results showed the coating reduced heat and smoke release during burning. Most important, more than 94% smoke was suppressed by the PDA-LDHs coating. Little cotton left after combustion but more than 10.2% of char was remained for the treated fabric by PDA-LDHs. On the other hand further covered by polydimethylsiloxane (PDMS), the treated cotton exhibited enhanced resistance to soiling and became more durable. For more than 96% oil/water separation efficiency, the treated cotton fabric can be expected to be an ideal filtration material.

Flame retardant effect and mechanism of nanosized NiO as synergist in PLA/APP/CSi-MCA composites

Abstract Intumescent flame retardants (IFRs) are widely used in preparing functional polymer composites , but it is still a challenge to improve their flame retardant efficiency. Herein nanosized nickel oxide (NiO) as synergist was incorporated into poly( l -lactic acid)/ammonium polyphosphate/silicone-containing macromolecular charring agent (PLA/APP/CSi-MCA) composites with the aim of improving their flame retardancy. According to limited oxygen index (LOI), vertical burning (UL-94) and cone calorimetry test results, the obtained PLA composites showed a LOI value as high as 33.0%, V0 ratting in UL-94 and 63.1% reduction for PHRR with the incorporation of 1 wt% NiO. The flame retardancy mechanism was also discussed by analyzing residual char structure and the composition of the liquid degradation products. It was found that the carbon layer contained two types of chars: APP and CSi-MCA could form char 1 via esterification and cross-linking reaction, while the PLA matrix could produce char 2 via the catalyzing carbonization of CSi-MCA and NiO to generate MWCNTs. The combination of char 1 and char 2 with better barrier effect resulted in the improvement on flame retardancy of PLA composites.

Boron nitride nanosheets decorated by bismuth ferrite particles: preparation, characterization, and effect on flame-retardant performance of epoxy resin

Bismuth ferrite nanoparticle decorated boron nitride nanosheets (denoted as BF-BNNS) were first prepared as hybrid flame retardants by a hydrothermal route. The microstructure and morphology of the as-prepared BF-BNNS were investigated by x-ray diffraction, Fourier transform infrared spectrometry and transmission electron microscopy. Furthermore, the as-prepared BF-BNNS nano-fillers were incorporated into epoxy resin (EP) matrix of 3 wt% in order to reduce the fire risks of EP; and their effect on the flame-retardant performance and thermal stability of EP was examined by cone calorimetry and thermogravimetric analysis, respectively. Cone calorimetry test results show that BF-BNNS as the nano-fillers contribute to reduce the peak heat release rate, peak smoke production release, and toxic CO production of EP by 34.7%, 35.6%, and 50.0%, respectively, showing good flame-retardant ability. And thermogravimetry analysis presents that the as-prepared BF-BNNS/EP nanocomposite exhibits a high char yield at elevated temperatures in air and nitrogen. Besides, thermogravimetry analysis–infrared spectrometry tests show that the volatile products of BF-BNNS/EP such as hydrocarbon compounds, aromatic compounds and CO were suppressed significantly. This is because layered structure BNNS function as the physical barrier while BF with catalytic activity promotes the char formation, thereby effectively inhibiting the transfer and diffusion of heat and mass and significantly reducing the fire risks of EP.

Application of metallic phytates to poly(vinyl chloride) as efficient biobased phosphorous flame retardants

ABSTRACTSimple, direct precipitation was used to synthesize green, renewable, biobased flame retardants. Copper phytate (Cu–Phyt), zinc phytate, aluminum phytate, and tin phytate (Sn–Phyt) were synthesized. Thermogravimetric analysis performed in N2 revealed that the metallic phytate (M–Phyt, where M is Cu, Zn, Al, or Sn) salts showed good charring. The limiting oxygen index (LOI), cone calorimetry (CONE) test data, tensile strength, and impact toughness were measured for flexible poly(vinyl chloride) (PVC) containing 15 wt % M–Phyt salts. The PVC/Sn–Phyt LOI rose from 24.9 to 30.3%, and the PVC/Sn–Phyt mechanical properties were on par with those of the pure PVC. The CONE test results indicate that PVC/Cu–Phyt showed the lowest total smoke production (TSP) and peak heat‐release rate (pHRR) among the samples. The TSP and pHRR of PVC/Cu–Phyt were 15.77 m2 and 181.77 kW/m2, respectively, 62.63 and 44.48% lower than those of the neat PVC. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46601.

Latent curing epoxy system with excellent thermal stability, flame retardance and dielectric property

To obtain a latent curing epoxy system with satisfactory thermal stability, flame retardance and dielectric properties, imidazolium dibenzo[c,e][1,2]oxaphosphate (IDOP) was synthesized by a facile way and utilized as a latent flame-retardant curing agent for epoxy resins (EP). It was confirmed that IDOP/EP one-pack system kept reactive inert near room temperature and cured efficiently under heating with a moderate heat release. The curing procedure was explored by X-ray photoelectron spectroscopy (XPS), confirming that the flame-retardant group was incorporated into epoxy chains by covalent and/or ionic bonds, hence the intrinsic flame retardance and excellent thermal stability were given to the cured resins finally. With only 15 wt% IDOP additions, the limiting oxygen index (LOI) increased to 37.0% from 20.5% of the reference sample, and UL-94 V-0 rating was achieved. The results of cone calorimetry test further certified that IDOP/EP showed satisfactory flame retardance dominating in gaseous phase, which was confirmed by the results of thermogravimetric analysis/infrared spectrometry (TG-IR). The thermal mechanical behavior of IDOP/EP was also evaluated by dynamic mechanical analysis (DMA). Especially, the incorporation of the flame-retardant group didn’t deteriorate the dielectric properties of the cured resin. Benefiting from the advances, the latent curing epoxy system with excellent comprehensive performance exhibited potential for versatile applications.

Preparation and characterization of surface‐modified ammonium polyphosphate and its effect on the flame retardancy of rigid polyurethane foam

ABSTRACTA functional surface‐modification agent was synthesized via a reaction between hexachlorocyclotriphosphazene and γ‐aminopropyl triethoxysilane. Ammonium polyphosphate (APP) was modified with this agent and then incorporated into a rigid polyurethane foam (RPUF). Fourier transform infrared spectroscopy, 1H‐NMR, and X‐ray photoelectron spectroscopy were used to characterize the modified ammonium polyphosphate (M‐APP). The results show that the dispersibility was improved and the particle size decreased after the modification. The limiting oxygen index and cone calorimetry test results show that M‐APP enhanced the flame‐retardant properties of RPUF. The peak heat‐release rate of polyurethane (PU)/20% M‐APP decreased by 51.18% compared with that of PU–APP. The scanning electron microscopy results illustrate that M‐APP facilitated the formation of intumescent and compact char. The excellent flame‐retardant performance of M‐APP resulted from the flame‐inhibition and barrier effects, which were attributed to the phosphazene group and the intumescent char, respectively. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 45369.