Flame retardant performance of a carbon source containing DOPO derivative in PET and epoxy

The combination of gas‐phase and condensed‐phase action will contribute to high quality flame retardant. A novel 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO)‐based flame retardant (DOPO‐DOPC), which contains carbon source was synthesized in favor of conducting the effect of gas‐phase as well as promoting the char formation in condensed‐phase. The chemical structure of DOPO‐DOPC was characterized by nuclear magnetic resonance (NMR) and Fourier transform infrared spectroscopy (FTIR). DOPO–DOPC was used as an additive in poly(ethylene terephthalate) (PET) and epoxy resin (EP). The flame retardancy of PET/DOPO‐DOPC and EP/DOPO‐DOPC composites were studied by limiting oxygen index (LOI) and UL‐94 test. The results showed that the incorporation of DOPO–DOPC into PET or EP could obviously improve their flame retardancy. The LOI values of modified PET or EP, which contained 10 wt % DOPO‐DOPC reached 42.8 and 31.7%, respectively. The thermogravimetric analysis (TGA) results revealed that DOPO–DOPC enhanced the formation of char residues. The Laser Raman spectroscopy (LRS) was used to investigate the carbon structure of thermal oxidation residues. Because of the combination of the gas phase flame retardant effect of DOPO moiety and the promoting formation of char residues in condensed phase, the PET and EP composites exhibited significant improvement toward flame retardancy. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44639.     

Synthesis and properties of a phosphate ester as curing agent in an epoxy resin system

Phosphate ester compounds display good flame retardancy effect in epoxy resin systems. In this paper, several novel phosphate esters, used as curing agents for epoxy resins, were synthesized based on P₂O₅, phosphoric acid, and different types of alcohol. The structures of phosphate esters were characterized by ³¹P nuclear magnetic resonance (³¹P NMR). Then, a series of flame retardant epoxy composites were prepared by curing the epoxy resins (E-44) with the phosphate esters. The flame retardancy and thermal degradation behaviors of flame retardant epoxy composites were investigated by cone calorimeter test (CCT) and thermogravimetric analysis (TGA), respectively. The results of CCT indicated that phosphate esters can significantly decrease heat release rate, total heat release (THR), and smoke production rate. The sample cured by butyl phosphate ester from phosphorus pentoxide, phosphoric acid and butanol showed the best flame retardant performance among all samples. The TGA results showed that phosphate esters could enhance char residues of flame retardant epoxy composites when compared with those of a composite using T31 as a curing agent at high temperature. It may be concluded that good flame retardant properties of flame retardant epoxy composites are related to the formation of a protective phosphorus-rich char layer. These phosphate esters have a good future on flame retardant epoxy composites.     

Preparation of a ternary hybrid of P-g-C3N4@PGS-Ti and its enhancement of the flame retardancy of epoxy resins

A novel ternary hybrid flame retardant named P-g-C₃N₄@PGS-Ti was prepared through step-by-step method. First, titanium dioxide was loaded on PGS to make PGS-Ti (where PGS = palygorskite), and then, PGS-Ti was decorated by phosphor-doped g-C₃N₄ (abbreviated as P-g-C₃N₄) to prepare a ternary flame retardant of P-g-C₃N₄@PGS-Ti. It showed that P-g-C₃N₄@PGS-Ti could efficiently improve the flame retardancy of epoxy resins (EP). The structure and the morphology of P-C₃N₄@PGS-Ti were characterized by Fourier transform infrared spectroscopy, X-ray diffraction, scaanning electron microscopy and hermogravimetric analysis (TGA). The flame retardancy and the burning behavior of 5 wt% P-g-C₃N₄@PGS-Ti composited EP were well investigated through TGA, limiting oxygen index (LOI), cone calorimeter test (CCT) and vertical burning test (UL-94 standard). It was found that the peak heat releasing (pk-HRR) of the EP/P-g-C₃N₄@PGS-Ti composite reduced 36% (from 1459 to 852 kW/m²) with the addition of 5 wt% of P-g-C₃N₄@PGS-Ti flame retardant to the matrix of EP. The combustion residue analysis showed that the EP/P-g-C₃N₄@PGS-Ti composite gained the most continuous and firmest char yield due to the synergistic effect of PGS, TiO₂ and the introducing of P element. The mechanism proved that the combination of gas phase and condensed phase flame-retardant processes were well coordinated to improve the fire retardancy for EP. We tested and studied the mechanical properties of EP/P-g-C₃N₄@PGS-Ti composites. Only 2.4% decreasing of flexural strength and 23.5% decreasing of impact strength in EP/P-g-C₃N₄@PGS-Ti composites compared to pure EP, respectively. But according to the test results of EP/P-g-C₃N₄@PGS-Ti composite material and the control sample in the system, EP/P-g-C₃N₄@PGS-Ti composite material had the highest flexural modulus and impact strength.     

Synthesis of a novel phosphonate flame retardant and its application in epoxy resins

A novel phosphonate flame retardant additive bis(2,6‐dimethyphenyl) phenylphosphonate (BDMPP) was synthesized from phenylphosphonic dichloride and 2,6‐dimethyl phenol, and its chemical structure was characterized by Fourier transform infrared (FTIR) spectroscopy, ¹H and ³¹P nuclear magnetic resonance. The prepared BDMPP and curing agent m‐phenylenediamine were blended into epoxy resins (EP) to prepare flame retardant EP thermosets. The effect of BDMPP on fire retardancy and thermal degradation behavior of EP/BDMPP thermosets was investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter and thermalgravimetric analysis (TGA). The morphologies of char residues of the EP thermosets were investigated by scanning electron microscopy (SEM) and the water resistant properties of thermosets were evaluated by putting the samples into distilled water at 70°C for 168 h. The results demonstrated that the cured EP/14 wt % BDMPP composites with the phosphorus content of 1.11 wt % successfully passed UL‐94 V‐0 flammability rating and the LOI value was as high as 33.8%. The TGA results indicated that the introduction of BDMPP promoted EP matrix decomposed ahead of time compared with that of pure EP and led to a higher char yield at high temperature. The incorporation of BDMPP enhanced the mechanical properties and reduced the moisture absorption of EP thermosets. The morphological structures of char residue revealed that BDMPP benefited to the formation of a more compact and homogeneous char layer on the materials surface during burning, which prevented the heat transmission and diffusion, limit the production of combustible gases and then lead to the reduction of the heat release rate. After water resistance tests, EP/BDMPP thermosets still remained excellent flame retardancy. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42765.     

ZnO对PP/MPP/PEPA膨胀阻燃体系的协同作用

以ZnO为阻燃协效剂,采用多聚磷酸蜜胺(MPP)和笼状季戊四醇磷酸酯(PEPA)复配阻燃剂,制备了具有良好阻燃性能的无卤阻燃PP。研究了ZnO用量对PP阻燃性能和协效作用的影响。结果表明:添加少量的ZnO即可显著提高PP的阻燃性能。当MPP、PEPA和ZnO添加量分别为12%、8%和1%时,阻燃PP的氧指数高达29.5%。TGA、FTIR分析和体式显微镜观测结果表明:添加ZnO可以催化MPP/PEPA间的酯化反应,促进体系成炭,形成更致密的炭层,从而提高材料的阻燃性能。     

Preparation of novel biomass humate flame retardants and their flame retardancy in epoxy resin

Humic acid (HA), a biomass material with plentiful oxygen-containing functional groups, showed huge potential to be considered as a promising charring agent in flame retardancy. In this study, this HA was modified with four different metal ions like Fe²⁺, Mn²⁺, Al³⁺, and Cu²⁺ and finally, introduced into the epoxy resin (EP) to enhance the flame retardancy of the EP and the dispersion of these flame retardants into the EP matrix. When 10 wt% of HA-Fe and HA-Mn were incorporated into EP matrix, the limiting oxygen index (LOI) was increased from 21.2% for EP to 26.6 and 25.3% for the EP composites and the peak heat release rate (pHRR) was reduced by 36 and 35.5%, respectively. Such a significant improvement in flame retardancy was attributed to the catalytic charring of HA in the presence of metal ions, which ultimately increased the residual char formation and produced compact char layers during the combustion process to retard the transfer of heat and combustible gases between the EP composites and the flame zone. Finally, this kind of application provided a feasible way for the development of an environmentally friendly flame retardant with high efficiency, which improved the fire safety of EP matrix.     

磷氮阻燃剂/协效剂对PA9T的阻燃性、热稳定性的影响

探究二乙基次磷酸铝(ADP)、三聚氰胺聚磷酸盐(MPP)及不同协效剂(勃姆石、无水硼酸锌(ZnB)、锡酸锌、三氧化钼)对PA9T阻燃性能的影响,且定量分析阻燃体系的分散性,同时分析阻燃体系的阻燃机理。结果表明:当m(ADP)∶m(MPP)=2∶1,PA9T/ADP/MPP的LOI值为38.5%,UL-94达到V-0级,阻燃效果最佳。PA9T/13.3%ADP/6.7%MPP的实际残炭率高于理论残炭率,表明ADP/MPP的引入促使PA9T在凝聚相交联成炭。协效剂对PA9T阻燃性能的影响程度排序为:ZnB>三氧化钼>锡酸锌>勃姆石。PA9T/FR/ZnB复合材料的烟气释放最低,燃烧后碳氢化合物的释放量显著降低,CO₂释放量提高。复合材料燃烧后形成连续、致密的炭层,且炭层中存在磷酸类物质、碳氧化物及铝氧化物等,具有典型的凝聚相阻燃机理。     

Novel multi-element DOPO derivative toward low-flammability epoxy resin

In order to obtain cured epoxy resin (EP) with satisfactory thermal stability and flame retardancy, a multi-element P/N/Si-containing flame retardant (DPAK) was synthesized by a facile way and was used as a reactive flame retardant to prepare flame-retardant EP. The flame-retardant efficiency of DPAK was subsequently evaluated by limiting oxygen index (LOI), UL-94, and cone calorimeter (CC) test. With a low incorporation amount of DPAK (4 wt%), the resultant EP achieve to UL-94 V-0 rating, and the corresponding LOI value reached to 30%, which was higher than that of EP containing DOPO (2.9 wt%). More importantly, the thermogravimetric analysis (TGA) revealed their higher thermal stability than those of EP containing DOPO. Furthermore, dynamic mechanical analysis (DMA) shown the maintained glass transition temperature of DPAK-EP. The increase of CO/CO₂ ratio in the CC test for the DPAK-EP samples proved the gas-phase activity of DPAK. Additionally, DPAK showed evidence of condensed phase activity by increasing char residue in TGA and CC test. The scanning electronic microscope together with the energy dispersive X-ray spectrometer (SEM–EDX) and X-ray photoelectron spectroscopy (XPS) exhibited that DPAK promoted the formation of compacted phosphorus-silicon char layer. Subsequently, TG-FTIR results indicated that DPAK-EP produced lesser combustible gases than neat sample did, improving flame-retardant properties of epoxy resin.     

纳米Al_2O_3对含磷环氧树脂体系的性能影响

研究了以纳米Al_2O_3作为协同阻燃剂,对EP/DOPO和EP/HPCTP树脂固化物阻燃性能的影响。通过热重分析测试(TGA)、动态热机械分析测试(DMA)、氧指数测定(LOI)及垂直燃烧测试(UL-94)重点探讨了树脂固化物的耐热及阻燃性能。测试结果表明,含磷阻燃剂有助于提高环氧树脂固化物的阻燃性能,但会降低其玻璃化转变温度(Tg)。随着纳米Al_2O_3的加入,残炭率(800℃)、极限氧指数(LOI)得到进一步的提高,并且能够在一定程度上提升树脂固化物的玻璃化转变温度(Tg)和初始热裂解温度(T5%)。     

Study on char reinforcing of different inorganic fillers for expandable fire resistance silicone rubber

Sodium silicate monohydrate (NSH), glass frits (GF) and aluminum hydroxide (ATH) were incorporated into room temperature vulcanized (RTV) silicone rubber (SR) as char reinforcing materials to improve the fire resistance of intumescent flame retardant silicone rubber. SR composites containing only intumescent flame retardant such as phosphorus nitrogen composite flame retardant (NH₂-C) and expandable graphite (EG) were used as comparison samples. Limiting oxygen index (LOI) test, vertical burning test (UL-94), flame resistance test, scanning electron microscopy (SEM) and X-ray diffraction spectroscopy tests, as well as volume variation and compression strength of char residues were used to discuss the effects of the above-mentioned fillers on the fire resistance, char residue strength and char integrity of SR composites. The results showed that SR composite filled with only intumescent flame retardants EG and NH₂-C had excellent flame retardancy. After adding ATH, the char residue was relatively dense and had good compressive strength, but its thermal insulation performance was reduced. GF or NSH reduced the flame retardancy of SR composites, but it obviously played a role in binding combustion residues, forming new crystals and improving the stability of char residues.     

成炭剂和分子筛协同MPP对PA6的阻燃性研究

将聚磷酸三聚氰胺(MPP)作为阻燃剂阻燃PA6,研究了高效成炭(剂CFA)和4A分子筛对MPP阻燃PA6性能的影响,并通过热失重分(析TGA)对材料进行了表征。结果表明:CFA和4A分子筛对MPP具有协效阻燃作用,加速了PA6阻燃时的成炭化学反应,改善了炭层结构。当阻燃体系中添加26%的MPP、4%的CFA和2%的4A分子筛时P,A6的氧指数可达到35%,垂直燃烧通过UL94 V—1级。     

Synthesis of a novel cross‐linked organophosphorus‐nitrogen containing polymer and its application in flame retardant epoxy resins

A novel cross‐linked organophosphorus–nitrogen polymetric flame retardant additive poly(urea tetramethylene phosphonium sulfate) defined as PUTMPS was synthesized by the condensation polymerization between urea and tetrahydroxymethyl phosphonium sulfate. Its chemical structure was well characterized by Fourier transform infrared (FTIR) spectroscopy, ¹³C and ³¹P solid‐state nuclear magnetic resonance. The synthesized PUTMPS and curing agent m‐phenylenediamine were blended into epoxy resins to prepare flame retardant epoxy resin thermosets. The effects of PUTMPS on fire retardancy and thermal degradation behavior of EP/PUTMPS thermosets were investigated by limiting oxygen index (LOI), vertical burning test (UL‐94), cone calorimeter measurement, and thermalgravimetric analysis (TGA) tests. The surface morphologies and chemical compositions of char residues for cured epoxy resins were investigated by scanning electron microscopy and X‐ray photoelectron spectroscopy (XPS), respectively. Water resistant properties of epoxy resin thermosets were evaluated by putting the samples into distilled water at 70°C for 168 h. The results demonstrated that the EP/12 wt% PUTMPS thermosets successfully passed UL‐94 V‐0 flammability rating and the LOI value reached 31.3%. The TGA results indicated that the incorporation of PUTMPS promoted epoxy resin matrix decomposed and char forming ahead of time, which led to a higher char yield and thermal stability for epoxy resin thermosets at high temperature. The morphological structures and analysis of XPS for the char residues of the epoxy resin thermosets shown that PUTMPS benefited to the formation of a sufficient, more compact, and homogeneous char layer with rich flame retardant elements on the materials surface during burning, which prevented the heat transmission and diffusion, limited the production of combustible gases, inhibited the emission of smoke, and then led to the reduction of the heat release rate and smoke produce rate. After water resistance tests, EP/12 wt% PUTMPS thermosets still remained excellent flame retardancy. Copyright © 2015 John Wiley & Sons, Ltd.     

Synthesis and characterization of a DOPO-substitued organophosphorus oligomer and its application in flame retardant epoxy resins

Advanced flame retardant epoxy resins with different contents of poly(DOPO substituted phenyl dimethanol pentaerythritol diphosphonate) (PFR) were prepared. PFR was synthesized from the polycondensation of DOPO-disubstituted benzenedimethanol (TDCA-DOPO) with pentaerythritol diphosphonate dichloride (SPDPC). The flame retardancy and thermal stability of the EP/PFR hybrids were investigated by limiting oxygen index (LOI), UL-94 test and thermogravimetric analysis (TGA) in air. LOI values increased from 21.5 for pure EP to 36.0 for phosphorus-containing resins, and UL-94 V-0 materials were obtained with the 15 wt% PFR. The TGA results indicated that incorporation of PFR significantly enhanced the char yield and the thermal stability of char layer at higher temperature. Differential scanning calorimetry revealed that the EP/PFR composites possessed higher glass transition temperatures than phosphorus-free EP, which was consistent with dynamic mechanical analysis results. The thermal degradation behaviors of the EP/PFR composites were investigated by real time Fourier transform infrared spectra (RTFTIR), thermogravimetric analysis/infrared spectrometry (TG–IR) and direct pyrolysis/mass (DP–MS) analysis. The results suggested that the addition of PFR can reduce the release of combustible gas, trap the H and OH radicals by releasing the PO radical and induce the formation of char layer, thus retard the polymer degradation and combustion process.     

三聚氰胺聚磷酸盐/硼酚醛协效体系阻燃PA66/GF复合材料的研究

采用氮磷型阻燃剂三聚氰胺聚磷酸盐(MPP)与硼改性酚醛树脂(BPF)组成的复合阻燃体系对玻纤(GF)增强尼龙66( PA66)复合材料进行阻燃,获得了阻燃性能优异、力学性能良好的增强复合材料,研究了协效阻燃剂BPF/MPP配比、BPF/MPP用量及GF用量对阻燃复合材料阻燃性能的影响,采用微型燃烧量热和质量保持率分析方法研究了阻燃复合材料的燃烧及成炭行为,对复合阻燃剂的协效机理进行了讨论.结果表明,当BPF在BPF/MPP中的质量分数为15％时,添加25％ BPF/MPP复合阻燃剂可使20％ GF增强PA66复合材料达到V-0( 1.6 mm)阻燃级别,极限氧指数增加至25.3％,拉伸强度、弯曲强度、缺口冲击强度分别为116 MPa,132 MPa,7.1 kJ/m2.该复合材料可满足高性能无卤阻燃的使用要求.     

Excellent role of Cu2O on fire safety of epoxy resin with ammonium polyphosphate based on the construction of self-intumescent flame retardant system

This work reports an effective self-intumescent flame retardant system for epoxy resin (EP) based on the remarkable synergistic effect between Cu₂O and ammonium polyphosphate (APP). The effect of Cu₂O/APP on improving EP's fire performance was evaluated by limited oxygen index (LOI), UL-94, and cone calorimeter test. The optimal mass ratio of Cu₂O: APP was shown to be 2:8. With 15 wt% total flame retardant loading, the EP with optimum Cu₂O/APP formulation reached V-0 classification and high LOI (33.5%), while the EP with APP only got NR and low LOI (26.5%). Additionally, the pHRR, total heat release, total smoke production, CO production of the EP with optimum Cu₂O/APP formulation were primarily decreased. All the improvements were ascribed to the formation of the self-intumescent char layer of EP resulted from the catalyzing effect of Cu₂O for char formation and CO to CO₂ conversion. These findings will consolidate approaches for conferring flame retardancy to flammable polymers or their blends.     

Synthesis of aluminum ethylphenylphosphinate flame retardant and its application in epoxy resin

A novel flame retardant additive, aluminum ethylphenylphosphinate (AEPP), was synthesized from diethyl phenylphosphonite and aluminum chloride hexahydrate, and characterized by FTIR, ¹H NMR, and ³¹P NMR. AEPP was added into diglycidyl ether of bisphenol A epoxy resin (EP) cured by bisphenol A‐formaldehyde novolac resin. The flame retardancy of the cured EP was investigated by limited oxygen index, UL 94 test, and cone calorimeter test. The results revealed that the EP composite containing 15% AEPP had a limited oxygen index value of 28.2% with a UL 94 V‐0 rating. The incorporation of AEPP effectively decreased the peak heat release rate and the total heat release in cone calorimeter test analysis. Scanning electron microscopy results showed that the introduction of AEPP benefited to the formation of a smooth and continuous char layer during combustion of the flame retarded EP. The thermogravimetric analysis results indicated that the incorporation of AEPP promoted the initial decomposition of EP matrix, but AEPP/EP composites had a higher char yield at high temperatures. Moreover, the flexural properties of the flame retarded EP composites were studied.     

Fire,thermal and mechanical properties of TPE composites with systems containing piperazine pyrophosphate (PAPP), melamine phosphate (MPP) and titanium dioxide (TiO2)

ABSTRACT

A novel synergistic flame retardant system containing piperazine pyrophosphate (PAPP) synthesised by polycondensation, melamine phosphate (MPP) and titanium dioxide (TiO₂) was applied to the thermoplastic elastomer (TPE). The char residues of TPE/PAPP/MPP/TiO₂ composites were 23.5 wt-% in N₂ and 17.3 wt-% in air. Meanwhile, the as-obtained composites showed enhanced flame retarding properties including high limit oxygen index (LOI) valuing (37.8 vol.-%) and UL-94 V-0 rating. TGA results indicated that the fire retardant systems significantly altered the initial decomposition temperature (5-20°C) and resulted in the formation of increased residues (23.5 wt-% in N₂ and 17.36 wt-% in air). In addition, the scanning electron microscope (SEM) test and gas analysis proved that char formation was significantly accelerated in this system. Non-combustible gases like ammonia and carbon dioxide could dilute the concentration of combustible gas, and result in the fuel reduction action as the minor. The heat and smoke release behaviours were also measured by cone calorimeter. The tensile strength, elongation at break and notch impact strength of the FR-TPE composite increased by further substituting a portion of the PAPP with MPP and TiO₂. The flame retarding mechanism of this system was also studied by SEM-EDX.     

Carbon nanotubes coated with phosphorus-nitrogen flame retardant and its application in epoxy thermosets

ABSTRACT

Carbon nanotubes coated with phosphorus-nitrogen flame retardant (PDAP-CNTs) were produced. The compositions and structures of PDAP-CNTs were systematically characterized, and the flame retardancy of PDAP-CNTs/EP composites were also tested. The results indicated that PDAP-CNTs demonstrated excellent flame retardancy performance on the flame-retardant EP composites (FR-EP), incorporation of 5.0wt% PDAP-CNTs improved the LOI values of EP from 26.0% to 31.8% and reached UL-94 V-0 classification. The analysis of flame-retardant mechanism indicating the flame-retardant ability of PDAP-CNTs was ascribed to the synergism of the phosphorus-nitrogen containing coating layer (PDAP) and CNTs.     

Synergistic effects of aluminium hypophosphite on the flame retardancy and thermal degradation behaviours of a novel intumescent flame retardant thermoplastic vulcanisate composite

ABSTRACT

The synergistic effects of aluminum hypophosphite (AHP) on the flame retardancy, thermal degradation behaviors of a novel intumescent flame retardant thermoplastic vulcanizate (TPV/IFR) composite were investigated. The results showed that the combination of AHP with IFR showed evident synergistic effects on the increase in the LOI value and reduction of the combustion parameters for the TPV/IFR/AHP composites at the optimum weight ratio of IFR/AHP (6/1) as evidenced by LOI, UL-94 and CCT. The TGA data revealed that AHP could change the degradation behavior of TPV/IFR composites and enhance the thermal stability of the TPV/IFR composites at high temperature. The results of FTIR, EDXS, LRS and SEM demonstrated that TPV/IFR/AHP composites could form more continuous, dense and stable char layer on the materials surface, and consequently improving the flame retardancy. Based on these results, the possible condensed flame retardant mechanism of TPV/IFR/AHP composites was concluded in detail.     

Functionalized Graphene Oxide Based on Hydrogen‐Bonding Interaction in Water: Preparation and Flame‐Retardation on Epoxy Resin

A novel functionalized graphene oxide (f‐GO) decorated with phosphorus/nitrogen (P/N)‐containing molecules is fabricated using a facile water‐based procedure. The chemical structure and micro‐morphology are well characterized by a combination of experimental and theoretical methods. Reactive force field‐based molecular dynamics simulations reveal at the atomic level that the GO sheets are successfully functionalized with P‐N flame‐retardant molecules by means of hydrogen bonds. Subsequently, f‐GO with extremely low loading is introduced into epoxy resin (EP) for reducing its flammability. Thermogravimetric analysis suggests that f‐GO significantly reduces the maximum mass loss rate of EP and enhances the char‐yield during heating. Combined with the results of a microscale combustion calorimeter and limiting oxygen index, EP/f‐GO2 shows better flame retardancy than the other nanocomposites. Furthermore, the presence of 2 wt% f‐GO substantially reduces the fire hazard of EP, resulting in 29.3% decline in the peak heat release rate, as well as 73% and 65% reduction in total smoke production and rate of smoke release, respectively, according to cone calorimetric tests. Based on the analyses of the char layers, f‐GO is determined to promote the formation of a more protective phosphorus‐containing char barrier for EP during combustion, indicating an effective condensed phase flame‐retardant mechanism.