Preparation of a chitosan‐based flame‐retardant synergist and its application in flame‐retardant polypropylene

A novel flame‐retardant synergist, chitosan/urea compound based phosphonic acid melamine salt (HUMCS), was synthesized and characterized by Fourier transform infrared spectroscopy and ³¹P‐NMR. Subsequently, HUMCS was added to a fire‐retardant polypropylene (PP) compound containing an intumescent flame‐retardant (IFR) system to improve its flame‐retardant properties. The PP/IFR/HUMCS composites were characterized by limiting oxygen index (LOI) tests, vertical burning tests (UL‐94 tests), microscale combustion calorimetry tests, and thermogravimetric analysis to study the combustion behavior and thermal stability. The addition of 3 wt % HUMCS increased the LOI from 31.4 to 33.0. The addition of HUMCS at a low additive amount reduced the peak heat‐release rate, total heat release, and heat‐release capacity obviously. Furthermore, scanning electron micrographs of char residues revealed that HUMCS could prevent the IFR–PP composites from forming a dense and compact multicell char, which could effectively protect the substrate material from combusting. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40845.     

Synthesis of polyhydric alcohol/ethanol phosphate flame retardant and its application in PU rigid foams

Two types of polyhydric alcohol/ethanol phosphates (PAEPs) were synthesized by a two‐step reaction using phosphorus oxychloride, ethanol, and polyhydric alcohol (glycerol and pentaerythritol). First, phosphorus oxychloride was reacted with ethanol to form a mixture of diethyl chlorophosphate and tri‐ethyl phosphate, and then PAEPs were prepared by the reaction between the above mixture and polyhydric alcohol. The chemical structures of PAEPs were characterized by ¹H NMR, and the elemental compositions were analyzed by X‐ray photoelectron spectroscopy (XPS). The degradation behavior of the PAEPs and their solubility in polyols were studied. The results indicated the PAEPs could be well dissolved in polyols. When PAEPs were used as flame retardant for PU rigid foams at a content of 8 wt %, the char residue of polyurethane foam at 800°C increased from 17.2 to 28% in average, and the peak heat release rate (pHRR) of polyurethane foam decreased significantly from 207 to 133 kW/m². In addition, PURF with PAEPs showed remarkable intumescent property. The results indicated that PAEPs were effective condensed phase flame retardant with char catalytic and intumescent property. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42298.     

Effects of Zinc Phytate on Flame Retardancy and Thermal Degradation Behaviors of Intumescent Flame-retardant Polypropylene

In this paper, zinc phytate was prepared and used as a synergist in intumescent flame-retarded polypropylene composites. The results showed that the polypropylene composites with 17?wt% intumescent flame retardant and 2?wt% zinc phytate have a limiting oxygen index 29.2 and achieve the UL-94?V-0 rating. Moreover, the peak heat release rate of the polypropylene composites decreases from 374 to 275?kW/m². Real-time Fourier-transform infrared spectroscopy showed that the zinc phytate delays the emission of carbon dioxide indicating that zinc phytate slows the degradation of polypropylene which regulates the suitability of intumescent flame-retardant system in polypropylene.     

Enhancement of wollastonite on flame retardancy and mechanical properties of PP/IFR composite

Wollastonite, a natural calcium metasilicate possessing acicular crystal habit structure, was used together with intumescent flame retardant (IFR) to flame retard polypropylene (PP). The synergistic effects between wollastonite and IFR were investigated using limiting oxygen index (LOI) test, cone calorimeter test, thermogravimetric analysis, scanning electron microscope‐energy dispersive spectrometer (SEM‐EDS), etc. The results revealed that wollastonite could effectively improve mechanical properties and flame retardancy of the PP/IFR composite. When 2.0 wt% wollastonite substituted for the same amount of IFR in the composite, the impact strength was enhanced from 4.6 kJ/m² to 6.8 kJ/m², which was increased by 47.1%. Meanwhile, the LOI was increased from 33.0% to 35.5%, a UL‐94V‐0 rating was achieved and the peak heat release rate decreased substantially from 314.4 kW/m² to 262.8 kW/m². Furthermore, the SEM‐EDS results provided positive evidence that the quality of char layer of the PP/IFR/wollastonite was superior to that of the PP/IFR composite due to synergism between wollastonite and IFR. POLYM. COMPOS., 35:158–166, 2014. © 2013 Society of Plastics Engineers     

Flame‐retardant and mechanical properties of high‐density rigid polyurethane foams filled with decabrominated dipheny ethane and expandable graphite

The article reported the flame‐retardant and the mechanical properties of expandable graphite (EG), an intumescent type, and decabrominated dipheny ethane (DBDPE), a gas‐phase type of flame‐retardant‐containing high‐density rigid polyurethane foams (RPUF) with a constant density of 0.5g/cm³. The results indicated that both EG and DBDPE could effectively interdict the burning of RPUF, besides, the EG exhibited more effective flame retardancy than the DBDPE. When the flame‐retardant loadings were 20 wt %, the LOI value of DBDPE‐filled RPUF increased to 33 vol %, while, surprisingly, the EG‐filled RPUF reached 41 vol %. Unfortunately, when they were both simultaneously added into RPUF, there was not any flame‐retardant synergistic effect. Although EG had outstanding flame retardancy, the compressive strength and modulus of 20 wt % EG‐filled RPUF dropped to only 9.1MPa and 229.7MPa respectively, which were lower than those of DBDPE (12.4 MPa and 246.8 MPa). The phenomena were ascribed to the different flame‐retardant mechanisms of EG and DBDPE, which were verified by scanning electronic microscope (SEM) observation of the burned surfaces. Besides, the dynamical mechanical analysis (DMA) demonstrated that the additions of EG and DBDPE made the glass transition temperature shift to the high temperatures, and the EG‐filled RPUF had the higher storage modulus. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Synthesis of bio-based reactive N/P flame retardant and its curing and flame retarding behavior in epoxy resins

In this study, a pioneering bio-based nitrogen–phosphorus flame retardant and curing accelerator named oxime-phosphazene hexakis [(4-(hydroxyimino) 2-methoxy) phenoxy] cyclotriphosphazene (HAPV) was successfully synthesized using hexachlorocyclotriphosphazene and vanillin. When 5 wt % HAPV was added into epoxy, the limiting oxygen index increased from 22% to 27% and passed UL-94 V-0 (UL is defined as Underwriters Laboratories) rating. Meanwhile, with the addition 5 wt% HAPV, the apparent activation energy (E_a) of HAPV/EP decreased from 20.22 to 67.15 kJ/mol, and the pHRR value was suppressed from 581.21 to 330.18 kW/m². It was due to that the HAPV quenched the combustion chain reaction through the gas phase and condensed phase, forming a dense char layer for blocking the heat transfer. Overall, the study provides an environmentally friendly epoxy flame retardant curing accelerator that shows great potential in epoxy flame retardant applications.     

Flame resistance and foaming properties of NBR compounds with halogen‐free flame retardants

Acrylonitrile butadiene rubber (NBR) foams compounded with various halogen‐free flame retardants were prepared. The influence of nonhalogen flame retardants on the flame resistance and foaming properties of the NBR compounds were investigated. The foaming properties (expandability 980%–1050%, closed‐cell structure) of NBR compounds with expandable graphite (EG) and ammonium polyphosphate (APP) flame retardants were similar to the NBR base compounds which contained primarily aluminum hydroxide (ATH). The heat release capacity (HRC) ranged from 10 to 74 J/g‐K, the average heat release rate (A‐HRR) ranged from 8 to 60 kW/m², and the total heat release (THR) ranged from 2.6 to 7.3 MJ/m² for the nonhalogenated NBR foams with closed‐cell structure and were significantly decreased upon increasing the amounts of flame retardants. This reduction is attributed to the hard char formation and production of water from the interaction with ATH. The limiting oxygen index (LOI) and time to ignition (TTI) show opposite results. The smoke density (0.050–0.037) of the NBR foams with EG flame retardant was decreased when compared to the NBR foam (0.107). The EG flame retardant was more effective than the phosphorus/nitrogen flame retardants in reducing the HRR and smoke density. The use of both ATH and EG is very effective in improving flame resistance. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Flame retarding effect of graphite in rotationally molded polyethylene/graphite composites

Linear low‐density polyethylene (LLDPE) compounds containing 10 wt % graphite fillers were rotationally molded into flat sheets. Flame retardancy was studied using cone calorimeter tests conducted at a radiative heat flux of 35 kW/m². Only the expandable graphite, an established flame retardant for polyethylene, significantly reduced the peak heat release rate. Compared with the neat polyethylene, it was easier to ignite the LLDPE composites containing carbon black, expandable graphite, and exfoliated graphite. However, rather unexpectedly, the inclusion of flake graphite increased the time to ignition by up to 80%. Simulations conducted with the ThermaKin numerical pyrolysis software suggest that increased reflectivity was mainly responsible for this effect. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41472.     

Influences of 4ZnO·B2O3·H2O whisker based intumescent flame retardant on the mechanical,flame retardant and smoke suppression properties of polypropylene composites

In this work, the influences of 4ZnO·B₂O₃·H₂O zinc borate (ZB) whisker based intumescent flame retardant (IFR) containing ammonium polyphosphate and dipentaerythritol on the mechanical, flame retardant and smoke suppression properties of polypropylene (PP) composites were characterized by the universal testing machine, UL-94, limiting oxygen index (LOI), and cone calorimeter tests, respectively. The results indicate that only 1 phr of ZB could effectively improve the LOI value and slow down the burning rate of PP composite. The peak heat release rate, average of HRR, total heat release, peak smoke production rate, and total smoke production values are all decreased from 413.8 kW/m², 166.3 kW/m², 82.3 MJ/m², 0.0995 m²/s, and 17.9 m² for PPc/20IFR composite to 267.8 kW/m², 128.3 kW/m², 66.8 MJ/m², 0.0478 m²/s, and 12.6 m² for PPc/20IFR/1ZB composite, respectively. The scanning electron microscopy images, energy dispersive spectrometry, and Raman spectra of char residue reveal that ZB is helpful to form a compact and graphitized intumescent char residue so that the heat diffusion and oxygen transmission are greatly hindered. The thermogravimetry analysis-fourier transform infrared spectroscopy (TGA-FTIR) results show that less combustible volatiles and more H₂O vapor are generated with the appearance of ZB. Hence, the combustion mechanism in gas phase is suppressed.     

Synergistic effect of phosphorus-containing nanosponges on intumescent flame-retardant polypropylene

A novel nanosponge (NS) was synthesized via the crosslinking of β-cyclodextrin with epoxy resin. Subsequently, a phosphorus-containing nanosponge (P–NS) was prepared by the absorbance of resorcinol bis(diphenyl phosphate) into the NS, and it was used as a synergistic agent of intumescent flame retardance in a polypropylene (PP)/melamine pyrophosphate/pentaerythritol composite. The synergistic effect between P–NS and the intumescent flame retardant (IFR) was investigated by thermogravimetry, limiting oxygen index (LOI) testing, vertical burning (UL-94) testing, cone calorimeter testing, and scanning electron microscopy (SEM). The results show that P–NS significantly improved the flame retardancy of the PP/IFR composite. When 3.0 wt % P–NS replaced the same amount of IFR in the composite, the LOI value increased from 29.0 to 32.5%, the UL-94 rating was enhanced from V-1 to V-0, and the peak heat release rate decreased substantially from 343 to 235 kW/m². Simultaneously, the total heat release and mass loss rate decreased dramatically. Furthermore, the SEM results show that the quality of char formation of the PP/IFR/P–NS was superior to that of the PP/IFR composite. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Flame retardancy and thermal properties of organoclay and phosphorous compound synergistically modified epoxy resin

Phosphorous flame retardants (PFRs) are common halogen‐free flame retardants. However, the flame retardancy of PFRs has not been fully exploited. Herein, the synergistic flame retardant effect of a typical phosphorous compound, 9,10‐dihydro‐9‐oxa‐10‐phosphaphenanthrene‐10‐oxide (DOPO), and organoclay on epoxy is studied. Results show that the peak of heat release rate (pHRR) and smoke production rate of modified epoxy resin (EP) with both 2.0 wt % phosphorus and 4.0 wt % organoclay are only 40% and 46% of that of neat EP resin, respectively, while the sole use of 2.0 wt % phosphorus only decrease the pHRR to 59% of that of neat EP resin. The structure and thermal decomposition behavior of as‐prepared nanocomposites are analyzed, and a synergistic flame retardant mechanism is proposed. This investigation opens a new approach to obtain halogen‐free EPs with higher flame retardancy and better overall properties than the EPs loaded with DOPO only. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43367.     

Improving the fire performance and smoke suppression of expandable polystyrene foams by coating with multi-dimensional carbon nanoparticles

Expandable graphite (EG) and modified multi-wall carbon nanotubes (ATH-MWNT) were introduced to expandable polystyrene (EPS) foams in order to improve its fire performance. The fire performance of EPS foams was evaluated by limiting the oxygen index (LOI), vertical burning (UL-94), and cone calorimetry tests. The results showed that the presence of 14.3% EG and 4.1% ATH-MWNT increased the LOI value from 18.0 to 30.3%, upgraded the UL-94 rating from no rating to V-0, completely eliminated melt dripping, and significantly decreased the peak heat release rate from 933 to 177 kW/m². Thermal analysis indicated that the thermal stability and char formation were improved by the presence of flame retardants. The char morphology was characterized by scanning electronic microscopy (SEM). It was suggested that the presence of EG and ATH-MWNT could form integrated char layers during combustion, which was beneficial to the formation of an intumescent protective char structure.     

The synthesis and characterization of a novel phosphorus–nitrogen containing flame retardant and its application in epoxy resins

A novel, halogen‐free, phosphorus–nitrogen containing flame retardant 2[4‐(2,4,6‐Tris{4‐[(5,5‐dimethyl‐2‐oxo‐2λ⁵‐[1,3,2]dioxaphosphinan‐2‐yl)hydroxymethyl]phenoxy}‐(1,3,5)‐triazine (TNTP) was successfully synthesized in a three‐step process, and characterized by FTIR, NMR spectroscopy, mass spectra, and elemental analysis. A series of modified DGEBA epoxy resin with different loadings of TNTP were prepared and cured by 4,4‐diaminodiphenylsulfone (DDS). Thermal gravimetric analysis and vertical burning test (UL‐94) were used to evaluate the flame retardancy of TNTP on DGEBA epoxy resin. The results showed that TNTP had a great impact on flame retardancy. All modified thermosets by using TNTP exhibited higher T_g than pure DGEBA/DDS. The loading of TNTP at only 5.0 wt % could result in satisfied flame retardancy (UL‐94, V‐0) together with high char residue (27.3%) at 700°C. The addition of TNTP could dramatically enhance the flame retardancy of DGEBA epoxy resins, which was further confirmed by the analysis of the char residues by scanning electron microscopy and FTIR. Furthermore, no obviously negative effect was found on the Izod impact strength and flexural property of DGEBA epoxy resins when TNTP loading limited in 5.0 wt %. DGEBA/DDS containing 2.5 wt % TNTP could enhance Izod impact strength from 10.47 to 10.94 kJ m^?2, and showed no appreciable effect on the flexural property (85.20 MPa) comparing with pure DGEBA/DDS (87.03 MPa). Results indicated that TNTP as a phosphorus–nitrogen synergistic intumescent flame retardant could be used for DGEBA epoxy resin. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41079.     

Synthesis of a novel flame retardant containing phosphazene and triazine groups and its enhanced charring effect in poly(lactic acid) resin

A novel flame retardant heax‐[N,N′,N″‐tris‐(2‐amino‐ethyl)‐[1,3,5] triazine‐2,4,6‐triamine] cyclotriphosphazene (HTTCP) containing phosphazene and triazine groups was synthesized and characterized by Fourier transform infrared spectroscopy (FTIR), solid‐state ¹H and ¹³C nuclear magnetic resonance (NMR) spectroscopy. HTTCP was applied to PLA matrix. The results of thermal gravimetric analysis (TGA), the limited oxygen index (LOI), and cone calorimeter test indicated that the HTTCP enhanced the thermal stability and flame retardant properties of PLA. When the mass fraction of HTTCP was 25 wt %, the PLA composite acquired a LOI value of 25.2% and the lower pk‐HRR at 290 kW/m². The excellent flame retardancy of HTTCP was attributed to the group synergistic effect between phosphazene and triazine groups. However, when combined HTTCP with APP (the total amount remaining 25 wt %, the ratio of HTTP to APP are 1:1 and 1:2), high values of LOI (over 40%) and UL94 V‐0 rating without dripping reached simultaneously. Meanwhile, the heat release rate, total heat release and mass loss rate were all decreased dramatically. Scanning electron microscopy (SEM) demonstrated that HTTCP/APP system benefited to the formation of more intumescent, dense, compact char layer on the materials surface which could effectively prevent the underlying material from degradation during burning. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44660.     

Study on the performance of flame‐retardant esterified starch‐modified cassava dregs‐PBS composites

Esterified starch was used as an interfacial modifier to treat the surface of cassava dregs. The treated fiber was used to prepare flame‐retardant poly(butylene succinate) (PBS)/cassava dregs fiber composites with the incorporation of intumescent flame retardants (IFR). The mechanical performance and flame‐retardant properties of composites were investigated. Experimental data showed that an appropriate cassava fiber loading favored the mechanical performance of composites. When the total filler content was 30 wt % [m(cassava dregs):m(IFR) = 1:5], in comparison with those of composite prepared by 30 wt % IFR, the tensile and impact strengths of composite increased by 40 ± 7 and 62 ± 8%, respectively. Besides, the limited oxygen index value of 37.3% and UL‐94 V0 rate of composite could be achieved. Possible flame retardant mechanism was proposed. The combusted residue of incorporated cassava dregs could play a support effect in the three‐dimensional charred layer formed by the combustion products of IFR and PBS. The three‐dimensional intumescent charred layer, and the formation of incombustible gas, such as NH3, play an important role in insulation, oxygen barrier, thereby effectively improving the flame retardancy and thermal stability of composites. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46210.     

Synergistic effects of fumed silica on intumescent flame‐retardant polypropylene

The synergistic effects of fumed silica on the thermal and flame‐retardant properties of intumescent flame retardant (IFR) polypropylene based on the NP phosphorus‐nitrogen compound have been studied by Fourier transfer infrared (FTIR) spectroscopy, cone calorimeter test (CCT), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), limiting oxygen index (LOI), and UL‐94 tests. The LOI and UL‐94 data show that when ≤1 wt % fumed silica substituted for the IFR additive NP can increase 2 to 4% LOI values of the PP blends and keep the V‐0 rating. The data obtained from the CCT tests indicate the heat release rates (HRR) reduce by about 23% for the PP/NP sample with 0.5 wt % fumed silica, whereas the mass loss rates (MLR) and total heat release (THR) values are much lower than those of the PP/NP samples without fume silica. The TGA data demonstrate that a suitable amount of fumed silica can increase the thermal stability and charred residue of the PP/IFR/SiO₂ blends after 500°C. The morphological structures of charred residues observed by SEM give positive evidence that a suitable amount of fumed silica can promote the formation of compact intumescent charred layers and prevent the charred layers from cracking, which effectively protects the underlying polymer from burning. The dynamic FTIR spectra reveal that the synergistic flame‐retardant mechanism of a suitable amount of fumed silica with IFR additive is due to its physical process in the condensed phases. However, a high loading of fumed silica restricts the formation of charred layers with P? O? P and P? O? C complexes formed from burning of polymer materials and destroys the swelling behavior of intumescent charred layers, which deteriorates the flame retardant and thermal properties of the PP/IFR blends. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Preparation of a novel synergistic flame retardant and its application in silicone rubber composites

Dehydration condensation product (DHCP) was prepared by addition and dehydration condensation reactions of 9,10-dihydro-9-oxa-10-phenanthrene-10-oxide (DOPO), vinyl trimethoxysilane, and (3-aminopropyl) triethoxysilane. DHCP-PA with high phosphorus content was prepared by reaction between DHCP and phytic acid (PA). It was then compounded with oxidized multi-walled carbon nanotubes (OMWCNTs) to prepare silicone rubber (SR) flame retardant composites. The results showed that the SR with a small amount of DHCP-PA owned good flame retardant effect. The heat release rate (HRR) was decreased from 436 kW/m² for pure SR to 288 kW/m² for the SR with 5 phr DHCP-PA, and the decreasing degree was 33.9%. After mixing 5 phr DHCP-PA with 1 phr OMWCNTs, the HRR of SR composite was decreased from 436 to 251 kW/m², the smoke production rate was decreased from 0.161 to 0.087 m²/s, the limited oxygen index value was increased from 20.4% to 28.4%, and the flame retardant grade can reach UL94 V-0. In addition, the synergistic flame retardant mechanism was researched and analyzed.     

Effect of modified layered double hydroxide on the flammability of intumescent flame retardant PP nanocomposites

The dodecyl sulfate intercalated CaMgAl-hydrotalcites (layered double hydroxides [LDHs]) were successfully prepared by co-precipitation method, and characterized by X-ray diffraction analysis, infrared spectroscopy (Fourier transform infrared spectra [FT-IR]), thermogravimetry (TG-DTA), scanning electron microscope, and Brunner−Emmet−Teller (BET). The prepared LDHs were added to the intumescent flame retardant (IFR) polypropylene (PP) nanocomposites, and the limiting oxygen index method (LOI), vertical combustion method (UL-94), cone calorimetry (CCT), and other test methods were used to study its thermal stability and combustion performance. The results showed that when the flame retardant was composed of 23 wt% IFR and 2 wt% O-SDS-LDHs, the LOI value of the material was increased to 31.5%, reaching the V-0 level, and the flame retardant performance was significantly improved. The results also showed that there was a significant synergistic effect between IFR and O-SDS-LDHs, which could improve the thermal stability and graphitization degree of PP nanocomposites. In addition, the peak heat release rate, total heat release, and total smoke production of the PP/IFR/O-SDS-LDHs system were 177 kW/m², 101 MJ/m², and 15.4 m², respectively, which were 82.2%, 51.0%, and 23.0% lower than those of pure PP, respectively. These improvements could be attributed to the presence of dense and continuous char layer formed by the synergistic effect.     

Influence of expandable graphite on flame retardancy and thermal stability property of unsaturated polyester resins/organic magnesium hydroxide composites

An eco-friendly flame retardant unsaturated polyester resin (UPR) material was prepared by combination organic magnesium hydroxide (OMH) and expandable graphite (EG). Different from direct addition of magnesium hydroxide (MH) in UPR matrix-like traditional method, OMH as a reactive monomer participates in the polycondensation reaction of UPR was more effective in improving the compatibility of flame retardant with matrix. Interestingly, the flame retardant UPR composites exhibited a more satisfactory flame retardant effect when a certain amount of 8 wt % EG was added into UPR/OMH matrix because of the synergistic effect between OMH and EG, resulted in the limited oxygen index from 21.7 to 28.5% and UL-94 test passed V-0 rating. Moreover, the peak heat release rate, total heat release, and smoke production rate of flame retardant UPR composites significantly reduced. The excellent flame retardancy was due to the formation of a dense and continuous carbon layer in the later stages of combustion. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020 , 137, 47881.     

Preparation of expandable graphite with silicate assistant intercalation and its effect on flame retardancy of ethylene vinyl acetate composite

A halogen‐free intumescent flame retardant expandable graphite composite (EG), with an initial expansion temperature of 202°C and expansion volume of 517 mL g⁻¹, was successfully prepared via a facile two‐step intercalation method, i.e. using KMnO₄ as oxidant and H₂SO₄, Na₂SiO₃·9H₂O as intercalators. The prepared EG flame retardant was characterized by field emission scanning electron microscope, X‐ray diffraction spectroscopy, energy dispersive spectroscopy and Fourier transform infrared spectroscopy. Furthermore, flame retardancy and thermal property of various ethylene vinyl acetate copolymer (EVA) composites, including EVA/EG and EVA/EG/APP (ammonium polyphosphate) specimens, were studied through limiting oxygen index instrument (LOI), vertical combustion UL‐94 rating, thermal gravimetric and differential thermal analysis. The results indicate that the EVA/EG and EVA/EG/APP composites exhibit a better flame retardancy. Addition of EG at a mass fraction of 30% leads LOI of 70EVA/30EG composite improved to 28.7%. Even more, the synergistic effect between EG and APP improves the LOI of 70EVA/10APP /20EG composite to 30.7%. This synergistic efficiency is attributed to the formation of compact and stable layer‐structure, and the prepared EG can make EVA composite reach the UL‐94 level of V‐0. POLYM. COMPOS., 36:1407–1416, 2015. © 2014 Society of Plastics Engineers