Cone Calorimetry Test Research Articles

Analysis of Flammability and Smoke Emission of Plastic Materials Used in Construction and Transport

This study provides valuable data on the specific toxic products that could be released from the commercially used, flexible polyurethane foams (FPUFs) during a fire. The steady-state tube furnace (Purser furnace) was used to generate combustion and thermal degradation products under different fire conditions. The concentrations of asphyxiates and irritant gases were determined using a Fourier transform infrared spectroscopy gas analyser. The volatile and semi-volatile organic compounds released in the fire effluents were collected using the solid-phase microextraction technique and identified by gas chromatography with a mass selective detector. In addition, the thermal stability of the FPUFs was evaluated by simultaneous thermal analysis. The cone calorimetry test was used to determine the flame retardancy of the selected materials. The obtained results show that the emission of carbon monoxide and hydrogen cyanide during the thermal degradation and combustion of the tested foams exceeded the permissible values and pose a serious threat to human life and health. Moreover, substituted benzenes, aldehydes, and polycyclic hydrocarbons were found in the released gases during all of the test conditions.

Study on the preparation of flame retardant plywood by intercalation of phosphorus and nitrogen flame retardants modified with Mg/Al-LDH

Wood-based material is widely used as a construction material due to its good mechanical properties, low production costs, and sustainability. However, its flammability limits applications in the field of construction. In this study, the two new phosphorus-nitrogen flame retardants were intercalated and modified with Mg/Al-LDH (abbreviated as UCPR-LDH and MCPR-LDH) and the resulting organic-inorganic synergistic flame retardants were prepared for formaldehyde-free flame retardant plywood. The results showed that the best intercalation effect was achieved with a mass ratio of 4:1 for LDH to UCPR and 2:1 for LDH to MCPR. The cone calorimetry test reveals that the total heat release of UCPR-LDH plywood is less than 8 MJ/m2 during 300 s of combustion, and the MCPR-LDH plywood reduces total smoke production by 70.6%. Meanwhile, the flame retardancy index (FRI) for the modified plywood was all “good”. Due to the synergistic effect of phosphorus and nitrogen flame retardants and LDH, the modified plywood exhibited good carbon-forming performance and higher graphitization during combustion, which play a role in cohesive phase protection and impeding the transfer of heat and combustible materials. In addition, the bonding strength of flame retardant-modified plywood decreased a little, but still meets industry standards. This work provides an environmental-friendly and simple method to prepare flame-retardant wood materials for construction applications.

Synthesis and evaluation of an eco-friendly and durable flame-retardant cotton fabrics based on a high-phosphorous-content

Cotton fabrics are extremely flammable. Therefore, ammonium salt of dipentaerythritol hexaphosphoric acid (ADPHPA), a novel reactive phosphorus flame retardant without halogen and formaldehyde, was synthesized by solvent-free synthesis method. Surface chemical graft modification was chosen to introduce flame retardant, imparting its flame retardancy and washability. SEM indicated that ADPHPA entered the interior of cotton fiber, which was grafted with OH of control cotton fabrics (CCF) by forming POC covalent bonds to obtain treated cotton fabrics (TCF). There were no apparent differences in the fiber morphology and crystal structure after treatment according to SEM and XRD analysis. TG analysis demonstrated that the decomposition process of TCF was changed compared with CCF, while lower heat release rate and total heat release of TCF indicated its combustion efficiency was also reduced based on cone calorimetry test. Meanwhile, in the durability test, TCF had undergone 50 laundering cycles (LCs) in accordance with AATCC-61-2013 3A standard and had a short vertical combustion charcoal length, which were able to be regard as durable flame-retardant fabrics. The mechanical properties of TCF decreased to a degree, but did not affect the actual use of cotton fabrics. Taken as a whole, ADPHPA has research significance and development potential as a durable phosphorus-based flame retardant.

Phase change material microcapsules with DOPO/Cu modified halloysite nanotubes for thermal controlling of buildings: Thermophysical properties, flame retardant performance and thermal comfort levels

Although the microencapsulated phase change material (MPCM) with organic core-shell structure is an effective means to encapsulate phase change material (PCM), it has the defects of low thermal conductivity and flammability. Herein, the flame retardant halloysite nanotubes (c-HNTs) doped by 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and Cu nanoparticles were successfully inserted in the MPCM to form a highway to heat transfer. The related examination and surface morphology showed that the DOPO structure anchored by Cu nanoparticles was grafted on the surface of halloysite nanotubes (HNTs) and the c-HNTs were successfully embedded in MPCM. The thermogravimetric analysis (TGA) proved that c-MPCM has the best thermal stability when compared to other samples, which is caused by the presence of c-HNTs. The differential scanning calorimetry (DSC) test indicated that MPCM delays the heat transfer to the capric acid while the HNTs improve this situation as thermal conduction channels. Then, the MPCM samples were added to the epoxy resin (EP). In the cone calorimetry test, we found that the heat and smoke release rate of EP composite is obviously reduced. Finally, the temperature control ability test of MPCM demonstrated that the EP composite with c-HNTs has the minimum temperature fluctuation. These properties will greatly stimulate the application of c-MPCM in insulation materials.

Bifunctional modification of cotton fabrics treated with a novel polysiloxane-based polymer: Flame-retardant and hydrophobic properties

Single-function textile auxiliaries are gradually unable to meet the requirements of the consumer market. Here, a novel polysiloxane-based polymer (HSCP) toward flame-retardant and hydrophobic bifunctional modification of cotton fabrics was synthesized using hydrogen-containing silicone oil and 3-(Dimethylphosphono)-N-methylolpropionamide as raw materials. The results of the Fourier transform infrared spectra (FT-IR), scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) confirmed that HSCP was processed to surface of cotton fabrics. For all treated cotton fabrics, their limiting oxygen index (LOI) values and damage lengths after the vertical burning test showed different degrees of increase and decrease, respectively, in terms of flame retardancy. Thermogravimetric (TG) and cone calorimetry tests showed that the thermal degradation process and combustion pathway of all treated cotton fabrics were significantly changed in comparison to the previous state. Moreover, the water contact angle test of cotton fabrics before and after treatment indicated that HSCP was also equipped with hydrophobic property. It was found that the water contact angles of cotton fabrics treated with 250 g/L, 350 g/L and 450 g/L of HSCP were enhanced to 140°, 150° and 158°, respectively. Overall, the analysis of these results identifies that HSCP has both flame retardant and hydrophobic functions on cotton fabrics.

Multi-chambered flame retardant microcapsules containing bisphenol A-bis (diphenyl phosphate) and zinc borate prepared by Pickering emulsions polymerization and their application in water-borne polyacrylic acid coatings

Multi-chambered flame retardant microcapsules (ZB-FRM) containing bisphenol A-bis(diphenyl phosphate) (BDP) and zinc borate (ZB) with calcium alginate (CA) shells were prepared by Pickering emulsions polymerization. The aim was to microencapsulate BDP to form a CA shell with many hydroxyl groups, improve its compatibility with aqueous polyacrylic acid (PAA), and reduce the flammability of PAA by using the flame suppression ability of BDP. Next, the high smoke generation caused by BDP was suppressed and the mechanical properties of the flame retardant coating were improved by introducing ZB in the shell layer. The thermal properties of the microcapsules, the mechanical and flame retardant properties in aqueous substrates, and smoke generation during cone calorimetry tests were tested. It was found that ZB-FRM had good compatibility with PAA. The introduction of ZB-FRM increased PAA's limiting oxygen index (LOI) to 25.5% and vertical combustion level to V-0. ZB improved the thermal stability of the microcapsules, the mechanical properties of the flame retardant coating, and the reduced smoke from BDP by 19.9%. However, ZB inhibited the initial flame retardant mechanism of BDP, resulting in a slight decrease in LOI, but still, a 6.9% improvement compared to pure PAA.

A high durable polysaccharide flame retardant based on phosphorus element for cotton fabrics

A novel polysaccharide flame retardant 2,6-dimethoxy polysaccharide ammonium phosphate (DOPSAP), was synthesized and characterized using nuclear magnetic resonance (NMR) and Fourier-transform infrared (FT-IR) spectroscopy. The characterization results of cotton samples suggested that DOPSAP was successfully grafted onto the cotton fabric through P-O-C covalent bonds. The char length and limiting oxygen index (LOI) of cotton fabrics treated with 30 wt% DOPSAP were 42 mm and 49.4%, and remained at 52 mm and 37.5% after 50 LCs in the violent washing conditions (AATCC 61–2013 3A washing standard), respectively. These results indicated that cotton fabrics treated with DOPSAP had excellent flame retardancy and durability. In the thermogravimetric (TG) analysis, the treated cotton retained 40.8% of the char residual at high temperature under N2 atmosphere. The total heat release (THR) of DOPSAP-treated cotton fabrics reduced from 4.2 to 2.1 MJ/m2 compared to untreated cotton fabrics in the cone calorimetry test. These results showed that DOPSAP inhibited the heat release of cotton fabrics during combustion by promoting the dehydration of cotton fabrics to produce more char, exhibiting a cohesive phase flame-retardant mechanism. The mechanical properties of the treated cotton fabric were remained well. The results showed that the flame retardant with relative high molecule based on polysaccharide and introducing more P element through P-C bonds are effective ways to improve the durability and flame retardancy of treated cotton.

Preparation and Properties of Smoke Suppressive Silicone Oil Modified by Dicyandiamide

In order to improve the smoke suppression of silicone oil, relatively high nitrogen content silicone oil was synthesized by the reaction of dicyandiamide (DCD) and epoxy-terminated silicone oil (ETSO) and named DCDSO. The molecular structure of DCDSO was characterized by Fourier transform infrared spectroscopy (FT-IR) and nuclear magnetic resonance spectroscopy (NMR). The flame ignition and cone calorimetry test (CCT) were used to investigate the smoke suppression effect of DCDSO. The results showed that the introduction of DCD significantly improved the smoke suppression performance of DCDSO. When the molar ratio of the epoxy group in ETSO and the primary amino group in DCD was 1:1.3, the flame height and the total smoke production were significantly reduced. Thermogravimetric analysis (TGA), thermogravimetric infrared analysis (TG-IR) and thermal field emission scanning electron microscopy (SEM) were used to explore the mechanism of smoke suppression. The mechanism of smoke suppression is that the introduction of DCD reduces the rearrangement decomposition, promotes the free radical oxidation decomposition and the formation of condensed phase, and thus reduces the generation and release of smoke.

Effect of a bio-based copolymer containing lysine, dopamine and triazine on flame retardancy and mechanical properties of thermoplastic polyurethane/ammonium polyphosphate

A bio-based copolymer (TDDL) containing lysine, dopamine, triazine was synthesized using cyanuric chloride, dopamine and lysine, respectively. The TDDL was used as a charring agent and ammonium polyphosphate (APP) was used as an acid source to improve the flame retardancy of thermoplastic polyurethane (TPU). The flame retardancy and thermal degradation behaviors of TPU blends were investigated using UL-94 vertical burning, limiting oxygen index (LOI), cone calorimetry tests and thermal gravimetric analysis (TGA). TPU blend containing 8 wt% APP displays a UL-94 V0 rating and a LOI value 30.0 vol%. While TPU blend containing 6 wt% APP/TDDL displays a UL-94 V0 and a LOI 29.6 vol% suggesting good synergistic effect between TDDL and APP. In addition, TDDL reduces the heat release rate of TPU/APP blend, and promotes the formation of a perfect char layer during the combustion process, and suppresses the release of combustible gas and smoke. Moreover, TPU blends have better modulus and elongation at break than those of TPU.

Influence of the Crystal Structure of Melamine Trimetaphosphate 2D Supramolecules on the Properties of Polyamide 6.

To explore the influence of the crystal structure difference of melamine trimetaphosphate (MAP) on the application performance of its polymer composites, an intumescent flame retardant with the optimal crystal type was designed and synthesized to improve the mechanical properties and flame retardancy of polyamide 6 (PA6). I-MAP and II-MAP were obtained using different concentrations of MA and sodium trimetaphosphate (STMP) in an acidic aqueous solution. The morphology, chemical composition, and thermal stability were comprehensively characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). The dispersion, mechanical properties, and flame retardancy of PA6/I-MAP and PA6/II-MAP were evaluated by SEM, stress and strain, limiting oxygen index test (LOI), vertical burning test (UL-94), cone calorimetry (CONE) test, and char residue analysis. The conclusion is as follows: I-MAP and II-MAP have a greater influence on the physical properties of PA6 but less influence on the chemical properties. Compared with PA6/I-MAP, the tensile strength of PA6/II-MAP is 104.7% higher, the flame rating reaches V-0, and PHRR is reduced by 11.2%.

Study on the flame retardancy of carrageenan fiber papers

Abstract Carrageenan fibers crosslinked with trivalent metal ions (Al3+ or Fe3+) were prepared into carrageenan fiber paper (Al/CAP, Fe/CAP) by the Rapid Kothen method, and their flame-retardant mechanism and flame retardancy were studied through LOI, VF, SEM, CONE, and TGA testing. The results showed that Al/CAP exhibited good flame retardancy and thermal stability, and its LOI value reached 52%. Meanwhile, the afterflame time and afterglow time of Al/CAP were 0 and 1 s, respectively, which indicated that it was not ignited and almost had no smoldering phenomenon. The flame-retardant performance of Fe/CAP is inferior to that of Al/CAP, with LOI of 32, but the total smoke emission (TSP) of Fe/CAP is lower in cone calorimetry test. Thus, CAPs (especially Al/CAP) can be widely used in the flame-retardant paper industry, due to their flame retardancy and environmental protection.

P/N Flame Retardant Based on a Pyrimidine Ring for Improving the Flame Retardancy, Mechanical Properties, and Smoke Suppression of Epoxy Resin

A P/N flame-retardant TBD based on a pyrimidine ring was devised and developed by reacting 2,4,6-triaminopyrimidine, benzaldehyde, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide to create a less toxic, low-smoke, and mechanically improved the flame-retardant epoxy resin (EP). The EP modified using TBD exhibited good transparency, which was attributed to the outstanding compatibility of TBD with the EP. With a phosphorus content of only 0.65%, EP/TBD10 passed the V-0 rating of the UL-94 test, and the limited oxygen index increased from 27.1% (pure EP) to 38.1%. In the cone calorimetry test (CCT), the peak heat release rate and the total heat release decreased by 34.9 and 45.7%, respectively, compared to pure EP. In addition, the modified cured EP exhibited good mechanical properties owing to the action of rigid groups and the formation of hydrogen bonds, and the tensile strength and modulus as well as the flexural strength and modulus of the samples were improved. In the smoke density test, EP/TBD20 received the ratings of HL1 and HL2 in Ds(4) and VOF4, respectively, according to EN45545-2. All results indicate that TBD is an efficient flame retardant that can enhance the flame retardancy and mechanical properties of the curing EP and reduce its smoke density, making it suitable for use in the rail transportation industry.

Development of Multifunctional Flame-Retardant Gel Coatings for Automotive Applications

Due to strict safety regulations, the automotive industry requires an effective reduction of flammability in polymer components. Flame retardants are usually added to the polymer matrix, affecting the viscosity of the matrix. Another possible solution is the application of coatings containing flame retardants, which can additionally ensure good surface quality and protection against external influences. In our research, the flammability of reference and flame retarded gelcoat base materials was investigated using oxygen index (LOI), UL-94, and mass loss type cone calorimetry (MLC) tests. Based on the flammability tests, the best results were obtained with the gelcoat formulation containing 15%P ammonium polyphosphate (APP) and the mixed formulation containing 5%P APP and 5%P resorcinol bis(diphenyl phosphate) (RDP), with a 55% and 64% reduction in the total heat release compared to the reference gelcoat, respectively. The two best-performing coatings were applied to polypropylene (PP) samples. 15%P APP reduced the peak heat release rate of PP by 89% compared to the reference. The gelcoat formulation containing 15%P APP was applied to polyurethane (PUR) automotive components, where the coating reduced the maximum heat release rate by 53% and shifted the time to peak heat release rate by 447 s.

MoS2 supported on acid activated kaolinite used in the kaolinite-epoxy resin composites for suppressing smoke toxicity and degradation

By growing molybdenum disulfide (MoS2) on the surface of acidified kaolinite (A-Kaol) to obtain MoS2@A-Kaol compounds, which effectively suppressed the toxic smoke and soot, enhanced thermal stability and ageing resistance of the epoxy resin (EP). In the cone calorimetry test, the total smoke production (TSP) reached 3917.6 m2; while the TSP value decreased to 2575.5 m2 after adding 3 wt% MoS2@A-Kaol; MoS2@A-Kaol slowed down the mass loss and promoted the char residue of EP composite increased to 11.3%. In TGA test, the temperature of 50% mass loss (T50%) was postponed from 388 °C to 414 °C and the residue increased to 8.7% after adding 3 wt% MoS2@A-Kaol, indicating the thermal degradation of the EP was postponed and its thermal stability was improved. The released smoke and soot were filtrated by a non-woven PP fabric, which documented MoS2@A-Kaol reduced the toxic aromatic volatiles. The tensile and impact strength of the EP was mostly kept by 3 wt% MoS2@A-Kaol after UV ageing for 72 h. Based on all the results, the smoke suppression and anti-ageing mechanism was disclosed. This work provided a feasible solution to improve the comprehensive properties of EP with low amount of filler.

Cross Network Composite Aerogel Towards Robust and Fire‐Resist Thermal Insulation Material

Thermal insulation materials with excellent fire safety and mechanical performances are urgently desired. Herein, novel cross network composite aerogels (CNCAs) are designed with cationic amylopectin and polyvinyl alcohol that act as the macromolecular framework and montmorillonite and borax that act as the functional binders. The CNCAs demonstrate low density (0.033–0.043 g cm−3), high strength (5.1–18.4 MPa), and anisotropic thermal conductivity. Furthermore, they exhibit high fire safety (limiting oxygen index > 50, UL‐94 V‐0 rating, and negligible heat and smoke release under cone calorimetry testing condition). Particularly, the after‐fire residue can still have an excellent load capacity with a compression modulus of 3.7 MPa. Based on the energy‐dispersive X‐ray spectroscopy results, up to avg. 91.3% of the carbon from the organic polymers remains in the residue. These characteristics not only ensure the safe use of the CNCAs but also expand their application fields and improve their durability.

New Polymer Composites with Aluminum Phosphates as Hybrid Flame Retardants.

Polymeric aluminum organophosphates are a class of nanostructured aluminum-based compounds that can be considered organic and inorganic hybrid materials. Aluminum phosphates have attracted considerable interest due to their ability to enhance composite materials' mechanical characteristics, lightweight, and thermal properties. Extensive studies have shown the potential of aluminum organophosphates as a component in the development of fire-retardant materials. Aluminum-organophosphorus hybrid (APH) materials have been prepared by reacting aluminum oxide hydroxide (boehmite) with alkyl and aryl phosphoric acids and used to prepare composites with epoxy resin. Boehmite is an aluminum oxide hydroxide (γ-AlO(OH)) mineral, a component of the aluminum ore bauxite. In this work, the composites based on epoxy resin Epidian 601 and commercial curing agent IDA were obtained. Pure boehmite and APH hybrids were added as flame retardants. FTIR and TGA analysis showed that obtained APH possesses a hybrid structure, high thermostability, and various morphologies. These new APH were incorporated into epoxy resin. The infrared spectroscopy confirmed the structure of hybrids and composites. Pyrolysis combustion flow calorimetry (PCFC) and cone calorimeter analyses were performed to assess the flame retardant properties of the composites. The results showed that the incorporation of 17 wt% APH allows a reduction of heat release rate but to a limited extent in comparison to pure boehmite, which is due to the different decomposition mechanisms of both boehmite and hybrids. The cone calorimetry test showed that residue contents correspond quite well to the mineral fraction from boehmite only. The hybrid APHs appear no more efficient than pure boehmite because the mineral fraction in APH is reduced while phosphate fraction cannot promote significant charring.

Developing flame-retardant, antibacterial cotton fabric by incorporating a linear polysiloxane-based coating

So as to meet the increasing demand of cotton fabrics in different fire safety scenarios, it is imperative to develop treatment agents with both flame retardant and antibacterial effects. Using linear polysiloxane as raw material, (DMH-BPMS) hydantoin-bromopropylmethylsiloxane was synthesized under mild conditions, which was mixed with ammonium polyphosphate (APP) and sodium alginate and coated on cotton fabrics. The structure of DMH-BPMS was characterized by Fourier transform infrared spectroscopy. The limiting oxygen index (LOI) and the vertical flammability test (VFT) show that the LOI value of DMH-BPMS/APP/Cotton can reach 29.8 %, and the char length was 9.6 cm, when the mass ratio of DMH-BPMS to APP is 3:2. Thermogravimetric analysis showed that DMH-BPMS/APP/Cotton had good thermal stability. Under nitrogen conditions at 750 ℃, the char residue rate is still as high as 38.93 %, which is higher than that (12.76 %) of cotton. Cone calorimetry test showed that the total heat release of DMH-BPMS/APP/Cotton decreased, the CO 2 release decreased, and TSP (total smoke production) decreased by 36 % compared with APP/Cotton. DMH-BPMS/APP/Cotton has an amazing antibacterial effect on Escherichia coli and Staphylococcus aureus, and the antibacterial rate can reach 97.8 % and 99.0 %. The whiteness of DMH-BPMS/APP/Cotton was 14.9 % lower than that of cotton. When the concentration of DMH-BPMS was 450 g/L, the maximum breaking strength of DMH-BPMS/APP/cotton in warp and weft directions increased by 48 % and 55 %. • It provides a new flame retardant and antibacterial multifunctional coating for cotton fabric. • It can effectively reduce the smoke emission of cotton fabrics treated with ammonium polyphosphate alone when burning. • One step method can effectively reduce energy consumption and improve production efficiency instead of two-step method.

A novel composite coating containing P/N/B and bio-based compounds for flame retardant modification of polyester/cotton blend fabrics

Herein, a novel composite coating containing P/N/B and bio-based compounds was developed and applied to the flame-retardant finishing of polyester/cotton (T/C) blend fabrics. The flame-retardant coating was prepared with a combination of triethanolamine borate, diethylenetriamine pentamethylene phosphonic acid and calcium alginate. The combined characterization of scanning electron microscopy (SEM) and energy dispersive spectrometer (EDS) proved that the coating system has been successfully processed to the surface of T/C blend fabrics. The results of limiting oxygen index (LOI), horizontal flammability test (HFT) and vertical flammability test (VFT) showed that the P/N/B/Ca-T/C blend fabrics obtained good flame retardancy and exhibited excellent char-forming ability. Meanwhile, the thermal stability and combustion behavior of the blend fabrics before and after coating were evaluated by thermogravimetric (TG) and cone calorimetry tests. Obviously, the flame-retardant coating transformed the thermal degradation process of T/C blend fabrics and suppressed their heat and smoke release during combustion. Furthermore, Fourier transform infrared (FTIR) spectroscopy of char layers and thermogravimetric-Fourier transform infrared spectroscopy (TG-IR) analysis indicated that the composite coating exerted flame retardancy to T/C blend fabrics in both the condensed and gas phases.

A flame retardant containing dicyandiamide and aluminum hypophosphite for polyethylene

Polyethylene (PE) is a widely used industrial plastic, but its flammable feature limits its further application. A novel composite based on dicyandiamide (DICY) and aluminum hypophosphite (AHP) was integrated into PE. FT-IR confirmed the chemical structures of the composite. During vertical burning and limiting oxygen index tests, the UL-94 flame retardant grade reached level V-0 and the LOI index increased from 18.8 % to 26.3 % when the ratio of AHP and DICY was 4: 1 (occupying 20 wt% of PE). The CCT tests showed the peak heat release rate of 4-AHP/DICY (AHP: DICY = 4: 1) decreased from 620.3 to 323.4 kW/m2 compared with pure PE. Moreover, the carbon residue of 4-AHP/DICY was higher than that of other samples. After cone calorimetry tests, a compact and stable carbon layer formed on the surface of PE composites through the digital photographs and SEM images of the char residue.

Effect of sepiolite on properties of silicone rubber/melamine/starch/sepiolite flame retardant composites

AbstractIn this work, a novel silicone rubber composite with low smoke, good mechanical property, and excellent flame retardant was prepared by introducing melamine (MEL), starch (St), and sepiolite (SEP) into SR. The effect of the amount of SEP on the mechanical properties of SR composites was investigated. The results showed that the mechanical properties were optimal when the amount of SEP was 30 phr. The tensile sections of the composites were characterized by SEM. The flame retardant properties of the composites were evaluated by oxygen index, vertical combustion, and cone calorimetry test (CCT). The thermal stability of the composites was tested by TGA. The flame retardant mechanism of the composites was also discussed. It was found that the strength and stability of the carbon layer of the composite were remarkably enhanced, and the flame retardant properties of the materials were improved with the addition of SEP. The SEM images of CCT carbon residues revealed that the carbon layer of the composite with SEP was more stable and had fewer cracks than that without SEP. This work provides new insights for the preparation of high‐performance SR composite.