Flame Retardant Ethylene-vinyl Acetate Research Articles

High-efficient flame retardant ethylene-vinyl acetate composites by incorporating monomolecular IFR and its pyrolysis behavior

Highly efficient flame retardant and excellent mechanical performance was critical for the application of ethylene vinyl acetate copolymer (EVA) composites. Herein, a monomolecular intumescent flame retardant poly(piperazine methylphosphonic acid pentaerythritol ester) defined as PPMPPE was incorporated into the EVA matrix, and the flame retardancy, mechanical performance of EVA composites were investigated. When 21 wt% PPMPPE was incorporated, the limiting oxygen index (LOI) of 1.6 mm EVA/PPMPPE composites was increased from 18.2 % for neat EVA to 27.5 %, and it achieved UL-94 V-0 grate during vertical burning tests. Meanwhile, the cone calorimetry tests indicated that the peak value of heat release rate and total heat release of FR-EVA composites were obviously reduced by 41.1 % and 27 % compared to neat EVA. The analysis of flame-retarded mechanism for EVA/PPMPPE indicated that PPMPPE facilitated the decomposition of EVA and formed an expanding char layer, and it possessed barrier effect in condensed phase. In addition, the PPMPPE could exert free radicals quenching effect and in gaseous phase. Therefore, the PPMPPE endowed the EVA matrix with good flame-retardant efficiency. Meanwhile, the mechanical performance of EVA/21 wt% PPMPPE composites was well maintained, and its tensile strength and elongation at break decreased by 21.9 % and 14.4 %, respectively. This research work provided a feasibility approach for producing EVA composites with excellent flame-retardant and mechanical performance.

A novel strategy for preparing ethylene‐vinyl acetate composites with high effective flame retardant and smoke suppression performance by incorporating piperazine pyrophosphate and Ce‐MOF

AbstractCerium‐containing metal organic framework defined as Ce‐MOF was prepared and then combined with piperazine pyrophosphate (PAPP) for preparing flame retardant ethylene vinyl acetate (EVA) copolymer composites. The samples of EVA/PAPP/Ce‐MOF achieved UL‐94 V‐0 rating with the limiting oxygen index (LOI) value of 31.3% when 17 wt% PAPP/Ce‐MOF with the mass fraction of 97:3 was introduced. Under the same loading amount of PAPP, the EVA/PAPP only obtained UL‐94 V‐1 rating with the LOI value of 26.9%. Cone calorimeter test confirmed that the total heat release and total smoke production of EVA/PAPP/Ce‐MOF significantly reduced from 132.8 MJ m−2 and 11.5 m2 for EVA/PAPP to 98.8 MJ m−2 and 7.3 m2, with a reduction of 25.6% and 36.5%, respectively. Besides, the maximum smoke density decreased from 488.8 and 375.9 for EVA and EVA/PAPP to 177.5 for EVA/PAPP/Ce‐MOF. It indicated that the addition of Ce‐MOF and PAPP effectively exerted synergistic flame retardant and smoke inhibition effect for EVA. Moreover, the addition of Ce‐MOF enhanced the compatibility of PAPP with EVA matrix, and water resistance of EVA/PAPP/Ce‐MOF was higher than that of EVA/PAPP. The x‐ray photoelectron spectroscopy texts of residual char of EVA composites indicated that the cerium ion complexed with phosphoric acid and polyphosphate generated by the thermal decomposition of PAPP and then more phosphorus elements remained in condensed phase. As a result, the sufficient, crosslinking and dense char layer with excellent intensity was formed, and the heat, combustible gas and smoke were efficiently inhibited. Consequently, the EVA materials were endowed excellent fire safety as well as low heat and smoke release.

Investigations of the improved insulation properties of flame-retardant ethylene vinyl acetate copolymer in the presence of nanocalcined kaolin

Investigations of the improved insulation properties of flame-retardant ethylene vinyl acetate copolymer in the presence of nanocalcined kaolin

A biobased flame retardant towards improvement of flame retardancy and mechanical property of ethylene vinyl acetate

A new biobased flame retardant (MHPA) with remarkable compatibility was synthesized via a facile and low-cost neutralization reaction of magnesium hydroxide (MH) and phytic acid (PA). By blending the prepared MHPA into ethylene vinyl acetate (EVA), the fire retardancy, smoke suppression and mechanical properties of the composites were significantly improved. When 50 wt% of MH was added into EVA matrix, the value of limiting oxygen index (LOI) reached 26.1%. Whereas, when 10 wt% MH in the EVA composites (with initial 50 wt% MH) was replaced by MHPA, the resulted EVA composites had a LOI value of 30.8%, indicating high efficiency of addition of MHPA to improve flame retardancy. Moreover, the heat release rate (HRR) and total smoke production (TSP) of the EVA composites reduced by 54.4% and 27.6%, respectively, suggesting that incorporation of MHPA could effectively hinder rapid degradation of EVA composites during burning process. The fire-retardant mechanism may reside in that the MHPA combined with MH can present the excellent carbonization and expansion effects. This study illustrates that the biobased MHPA has a broad application prospect to develop flame-retardant EVA composites.

Enhanced Flame Retardancy in Ethylene–Vinyl Acetate Copolymer/Magnesium Hydroxide/Polycarbosilane Blends

A polymer ceramic precursor material—polycarbosilane (PCS)—was used as a synergistic additive with magnesium hydroxide (MH) in flame-retardant ethylene–vinyl acetate copolymer (EVA) composites via the melt-blending method. The flame-retardant properties of EVA/MH/PCS were evaluated by the limiting oxygen index (LOI) and a cone calorimeter (CONE). The results revealed a dramatic synergistic effect between PCS and MH, showing a 114% increase in the LOI value and a 46% decrease in the peak heat release rate (pHRR) with the addition of 2 wt.% PCS to the EVA/MH composite. Further study of the residual char by scanning electron microscopy (SEM) proved that a cohesive and compact char formed due to the ceramization of PCS and close packing of spherical magnesium oxide particles. Thermogravimetric analysis coupled with Fourier-transform infrared spectrometry (TG–FTIR) and pyrolysis–gas chromatography coupled with mass spectrometry (Py–GC/MS) were applied to investigate the flame-retardant mechanism of EVA/MH/PCS. The synergistic effect between PCS and MH exerted an impact on the thermal degradation products of EVA/MH/PCS, and acetic products were inhibited in the gas phase.

Synergistic properties of microencapsulated intumescent flame retardant-organically modified montmorillonite/ethylene-vinyl acetate copolymer composites

Flame retardant ethylene-vinyl acetate (EVA) composites were prepared by combination of microencapsulated intumescent flame retardants-ammonium polyphosphate (APP)-pentaerythritol (PER) and organically modified montmorillonite (OMMT). The microencapsulated APP (MCAPP)-microencapsulated PER (MCPER)-OMMT/EVA composites were further characterized through XRD and TEM, confirming OMMT sheets are well dispersed in the matrix as exfoliated or intercalated nanocomposite state. Limiting oxygen index (LOI), TGA, underwriters laboratories 94 vertical burning (UL-94), cone and smoke density test results indicate the synergistic flame retardancy effect between MCAPP-MCPER and OMMT in MCAPP-MCPER-OMMT/EVA composites. Replacing the same amount of MCAPP-MCPER with 3wt% OMMT could improve the LOI value of the MCAPP-MCPER-OMMT/EVA composites from 25.5vol% to 29.5vol%. The UL-94 rating increases from V-2 to V-0. The char residue of MCAPP-MCPER-OMMT/EVA composites is improved from 14.5wt% to 15.9wt% and the smoke density significantly decreases from 154.7 g/s to 97.5 g/s. Besides, the mechanical property of MCAPP-MCPER-OMMT/EVA composites was tested by universal testing machine and dynamic thermomechanical analysis (DMA), the result shows that the flame-retardant MCAPP-MCPER-OMMT/EVA composites has better mechanical properties.

Stretchable and compressible conductive foam based on Cu nanowire/MWCNT/ethylene-vinyl acetate composites for high-mass-loading supercapacitor electrode

Stretchable and compressible conductor with a 3D structure has received widespread attention in smart robotics and deformable electronics, because of its special mechano-electrical properties. However, the poor mechanical properties, low electrical conductivity and unstable performance during deformation process are still the biggest technical bottlenecks. In this work, a stretchable and compressible conductive foam with stable mechano-electrical properties was comprised of copper nanowires (Cu NWs) and multi-walled carbon nanotubes (MWCNTs) that were wrapped firmly on flame-retardant ethylene-vinyl acetate (FR-EVA) skeleton. The 3D porous FR-EVA matrix with sufficient internal space provided a remarkable mechanicaldeformability for the composites foam. Additionally, the excellent conductivity of composites foam was mainly derived from the well-connected Cu NW networks, which were welded by chemical steam reduction method. Finally, the MWCNTs not only significantly improved the adhesion between the Cu NWs and FR-EVA skeleton but also effectively overcame the Cu NWs oxidation. Consequently, the 3D conductive composites foam possessed an excellent electrical conductivity (R = 2.40 Ω), mechanical stability (R/R0 < 1.6, after 100 cycles) and environmental stability (R/R0 < 1.3, exposed 33 days in air). When applied to supercapacitors, the composites foam as an excellent conductive carrier can effectively improve both mass loading and electrochemical performance of active materials. In a three-electrode cell, ~5.6 mg cm−2 of high-mass loading of activated carbon on the composites foam exhibited high specific capacitance, excellent cycle performance and remarkable compressing stability (85.97% of capacitance retention after 500 cycles), which is much better than that of commercialized Ni foam.

Simultaneously improving mechanical strength, hydrophobic property and flame retardancy of ethylene vinyl acetate copolymer/intumescent flame retardant/FeOOH by introducing modified fumed silica

Series of flame-retardant ethylene vinyl acetate (EVA) composites with excellent properties were prepared by adjusting the fraction of fumed silica (FS). The surface morphologies, mechanical property, hydrophobicity, thermal property and the related flame-retardant properties were measured and investigated in details. The scanning electron microscopy (SEM) and mechanical property results showed that the certain addition of FS could effectively improve the interface compatibility between EVA matrix and flame retardant (FR). Moreover, the tensile strength and elongation at break were increased to 20 MPa and 675.0 %, respectively. High hydrophobicity of the EVA composite could also be achieved proved by high contact angle (85°) and low water absorption (0.2 %), respectively. In addition, cone calorimeter test (CCT) results indicated the value of heat rate release of EVA composites decreased by 63.6 % with the addition of FS compared to pure EVA due to the formation of char layer by protecting char residue and insulating fire and heat transmission, which was confirmed by SEM and thermogravimetric analysis (TGA) analysis. Besides, the anti-dripping effect of FS was indicated by limiting oxygen index (LOI) and UL-94.

Flame-retardant ethylene vinyl acetate composite materials by combining additions of aluminum hydroxide and melamine cyanurate: Preparation and characteristic evaluations

There is a great interest to develop efficient fire-resistant materials. While ethylene vinyl acetate (EVA) is a widely used material, it suffers from the problem of relatively high inflammability which seriously hinders its usage as the product material with a high flame-retardant requirement. In this study, a strategy to combine aluminum hydroxide (ATH) and melamine cyanurate (MCA) with EVA was proposed to prepare the EVA composite materials with high flame resistance. It was found that slight addition of MCA could increase the lubricity of EVA and raise the compatibility between EVA and ATH. Thermogravimetric analysis (TGA) indicated that the thermal stability of EVA was improved via adding MCA, which was evidenced by the delayed thermal decomposition temperature. Moreover, the combustion results indicated that the EVA composite with 60 parts per hundred (phr) ATH and 40 phr MCA addition (EVA-60-40) displayed the optimal isolated layer favoring the fire resistance. In addition, the highest limiting oxygen index (LOI) value (27.5%) and V-0 rating of the EVA-60-40 as compared with other components indicated its incombustible nature. These results suggested the synergetic effect of ATH and MCA additions, the high efficiency of the proposed strategy and the wide application prospect of the produced EVA-ATH-MCA composite materials.

Phosphorization of exfoliated graphite for developing flame retardant ethylene vinyl acetate composites

Ammonium polyphosphate (APP) was grafted onto the surface of exfoliated graphite nanoplatelet (GNP) to obtain a novel flame retardant, GNP-g-APP, and thereafter was incorporated into the ethylene vinyl acetate (EVA) to improve its flame retardancy. The chemical structures of the precursors and the target product were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), thermogravimetric analysis (TGA), and energy dispersive X-ray spectroscopy (EDS) techniques. FTIR spectra appeared at 1056 and 1103cm−1 were attributed to POC asymmetric stretching bond, that conformed formation of GNP-g-APP. Thermal stability behaviour and flame retardancy performance of the samples were evaluated by TGA, UL-94, micro-calorimetry, and cone calorimetry. TGA measurements revealed the superiority of GNP-g-APP over GNP. The micro-calorimetry analyses indicated a sharp fall in both the total heat release (THR) and the peak of heat release rate (pHRR) of EVA containing 30wt.% GNP-g-APP, evidenced by a thick char layer formed as barrier. Cone calorimetry confirmed flame-retardant effect of GNP-g-APP featured by a reduction in pHRR (−63 %) and THR (−31.6 %) due to the formation of a cohesive char layer. Although GNP addition sharply decreased the elongation at break of 70/30 (w/w) composites from 500% for neat EVA to 71%, a very promising value of 364% for EVA/GNP-g-APP sample preserved superior flexibility.

Synergistic Effects of Nano-zinc Oxide on Improving the Flame Retardancy of EVA Composites with an Efficient Triazine-Based Charring Agent

The synergistic effect of nano-zinc oxide (nano-ZnO) on the flame retardancy and thermal stability of intumescent flame retardant ethylene–vinyl acetate (EVA/IFR) consisting of novel hyperbranched triazine-based charring agent (HTCFA) and APP was evaluated by limiting oxygen index (LOI), UL-94 measurement, cone calorimeter test (CCT) and thermogravimetric analysis (TGA), and the residue analysis was also carried out through scanning electron microscopy (SEM), fourier transform infrared (FTIR), laser raman spectroscopy (LRS), and X-ray photoelectron spectroscopy (XPS). The results showed that introducing a certain amount of nano-ZnO could obviously enhance LOI value and UL-94 rating, and effectively restrain the combustion performance of EVA/IFR composites, leading to the decrease of heat and smoke release. The addition of 0.5 wt% nano-ZnO into EVA/IFR composite obtained the highest catalytic effectivity (CAT-EFF). TGA results uncovered a distinct synergistic carbonization effect existed between nano-ZnO and IFR, and nano-ZnO could obviously improve the high-temperature thermal stability and promote the char formation of IFR and EVA/IFR. Analysis of final char residues proved that the incorporation of appropriate amount of nano-ZnO contributed to remaining more P and forming more high-quality graphitization char layers with richer P–O–C and P–N cross-linking structures in condensed phase owing to the catalytic carbonization effect of nano-ZnO on IFR system, which played a critical role in remarkable improvement of flame retardancy and smoke suppression properties of composites.

Enhancement of an organic-metallic hybrid charring agent on flame retardancy of ethylene-vinyl acetate copolymer.

An organic triazine charring agent hybrid with zinc oxide (OTCA@ZnO) was prepared and well characterized through Fourier transform infrared spectrometry (FTIR), solid-state nuclear magnetic resonance (SSNMR), transmission electron microscopy (TEM) and thermogravimetric analysis (TGA). The flame retardancy and thermal behaviour of intumescent flame retardant ethylene-vinyl acetate (EVA) composites combining OTCA@ZnO and ammonium polyphosphate (APP) were investigated using limited oxygen index (LOI), UL-94 vertical burning, cone calorimetry and TGA. The structure and morphology of chars were investigated by scanning electron microscopy (SEM), FTIR, laser Raman spectroscopy analysis (LRS) and X-ray photoelectron spectroscopy (XPS). Results revealed that OTCA@ZnO exhibited excellent thermal stability and dispersity after hybridization. The flame retardancy and smoke suppression properties of EVA were significantly improved by introducing APP/OTCA@ZnO. TGA results indicated that APP/OTCA@ZnO presented an excellent synergistic effect and promoted the char formation of EVA composites. Residue analysis results showed more char with high quality connected by richer P–O–C, P–N and P–O–Si structures was formed in APP/OTCA@ZnO system than APP/HOTCA/ZnO system, which consequently suppressed more efficiently the combustion and smoke production due to the in situ catalytic carbonization effect of hybrid.

Improved Flame-Retardant and Ceramifiable Properties of EVA Composites by Combination of Ammonium Polyphosphate and Aluminum Hydroxide.

Ceramifiable flame-retardant ethylene-vinyl acetate (EVA) copolymer composites for wire and cable sheathing materials were prepared through melt compounding with ammonium polyphosphate (APP), aluminum hydroxide (ATH) and fluorophlogopite mica as the addition agents. The effects of ammonium polyphosphate, alumina trihydrate, and APP/ATH hybrid on the flame retardant, as well as on the thermal and ceramifiable properties of EVA composites, were investigated. The results demonstrated that the composites with the ratio of APP:ATH = 1:1 displayed the best flame retardancy and the greatest char residues among the various EVA composites. The tensile strength of the composites was 6.8 MPa, and the residue strength sintered at 1000 °C reached 5.2 MPa. The effect of sintering temperature on the ceramifiable properties, microstructures, and crystalline phases of the sintered specimen was subsequently investigated through X-ray diffraction, Fourier transform infrared, and scanning electron microscopy. The XRD and FTIR results demonstrated that the crystal structure of mica was disintegrated, while magnesium orthophosphate (Mg3(PO4)2) was simultaneously produced at an elevated temperature, indicating that the ceramization of EVA composites had occurred. The SEM results demonstrated that a more continuous and compact microstructure was produced with the rise in the sintering temperature. This contributed to the flexural strength improvement of the ceramics.

Preparation of urea formaldehyde microsphere and its effect on flame retardant ethylene vinyl acetate composites

Urea formaldehyde microsphere (UFM) was prepared and used with organic montmorillonite (OMMT) to modify the flame retardant efficiency of ethylene vinyl acetate copolymer (EVA)/intumescent flame retardant (IFR) composites. The results show that single IFR may modify the flame retardancy of EVA, but its efficiency is not good enough. The EVA composite containing 21 wt% IFR is just classified the UL_94 V2 and has a limiting oxygen index (LOI) 24.7 vol%. Combining UFM with IFR does not improve the flame retardancy of EVA/IFR composites, and blending OMMT with IFR only improves its LOI. Adding 2 wt% UFM, 2 wt% OMMT, and 17 wt% IFR into EVA, it obtains the UL_94 V0 without melt dripping and a LOI 29.0 vol%. Also, the peak heat release rate and total heat release decrease a lot. Good synergistic effects among IFR, UFM, and OMMT improve the char residues and modify the char micromorphology of EVA composites, which provide better protect for the underlying resin.

Synergistic flame-retardant effects of aluminum phosphate and Trimer in ethylene–vinyl acetate composites

A series of flame-retardant ethylene–vinyl acetate (EVA) composites with different contents of aluminum phosphate (AHP) and Trimer were prepared. The synergistic flame-retardant effects of the Trimer with AHP in EVA/AHP blends were studied by limiting oxygen index (LOI) tests, UL-94 tests, cone calorimeter tests, thermogravimetric analysis, and scanning electron microscopy (SEM). The LOI and UL-94 results showed that the system containing AHP and Trimer was very effective in improving the flame retardancy of EVA. When the mass ratio of AHP and Trimer was 3:1, the highest flame retardancy could be obtained, and when the flame-retardant loading was 30 wt%, the EVA/AHP/Trimer (7.5%) sample could achieve the V-0 rating in UL-94 tests, at the same time, its LOI value was 24.4%. The TG and DTG results showed that the addition of flame retardants catalyzes EVA decomposition in the first stage and generates a more stable char residue in the second stage. Consequently, an efficient reduction in the flammability parameters, such as heat release rate, total heat release, smoke production rate, and total smoke production could be observed. In addition, it was observed from the SEM observations of the morphological features that the AHP and Trimer combination, at the optimum proportion, could promote the formation of compact charred layers and prevent their cracking, which effectively protected the underlying materials from burning.

Capitalizing on the molybdenum disulfide/graphene synergy to produce mechanical enhanced flame retardant ethylene-vinyl acetate composites with low aluminum hydroxide loading

We have engineered a flame retardant ethylene-vinyl acetate (EVA) composite which has the similar mechanical properties as polyvinyl chloride (PVC) and therefore may prove to be an alternative material for cable sheathing. Four composites were studied, EVA with aluminum hydroxide (ATH), EVA with ATH and molybdenum disulfide (MoS2), EVA with ATH and graphene nanoplatelets (GNPs), and EVA with all three components. Tensile testing showed nearly identical results for the EVA/ATH and EVA/ATH/MoS2 compounds, while the EVA/ATH/GNPs compound had higher mechanical properties. The compound containing all three components showed further enhanced mechanical properties, indicating that a synergy was established. This was further confirmed using Scanning Electron Microscopy (SEM) where GNPs were seen to increase the dispersion of the MoS2 and ATH components within the polymer matrix. Cone calorimetry test clearly showed a large decrease in heat release rate when GNPs were added, which was further enhanced by adding GNPs and MoS2 together. Application of the UL-94 test showed that only the compound containing 36 wt% of ATH and 2 wt% each of MoS2 and GNPs can achieve the UL-94 V0 rating.

Functionalized nanodiamond as potential synergist in flame-retardant ethylene vinyl acetate

Pristine and phosphorylated detonation nanodiamonds (ND) were incorporated in ethylene vinyl acetate (EVA) as potential synergist agents to improve flame retardancy. Combinations of 5wt% of pristine or modified ND and 20 or 25wt% of Ammonium Polyphosphate (APP) were investigated using ThermoGravimetric Analysis (TGA), Pyrolysis Combustion Flow Calorimeter (PCFC), and Cone Calorimeter (CC). The study of thermal stability shows that APP and pure ND interacts, resulting in the formation of a char residue which is stable up to 750°C. A strong reduction in the peak of HRR at Cone Calorimeter is highlighted for APP/ND combinations. PCFC data show that the peak of heat release rate (pHRR) decreases with the additive content. All these experiments suggest the formation of a thick charring layer, able to protect the material during thermal degradation. SEM micrographs confirm that EVA/APP/ND residues are more cohesive than EVA/APP ones.

Effect of electron beam irradiation and microencapsulation on the flame retardancy of ethylene-vinyl acetate copolymer materials during hot water ageing test

Microencapsulated ammonium polyphosphate (MCAPP) in combination with polyester polyurethane (TPU) was used to flame retardant ethylene-vinyl acetate copolymer (EVA). The EVA composites with different irradiation doses were immersed in hot water (80°C) to accelerate ageing process. The microencapsulation and irradiation dose ensured positive impacts on the properties of the EVA composites in terms of better dimensional stability and flame retardant performance. The microencapsulation of APP could lower its solubility in water and the higher irradiation dose led to the more MCAPP immobilized in three dimensional crosslinked structure of the EVA matrix which could jointly enhance the flame retardant and electrical insulation properties of the EVA composites. So, the EVA composites with 180kGy irradiation dose exhibited better dimensional stability than the EVA composites with 120kGy due to the higher crosslinking degree. Moreover, the higher irradiation dose lead to the more MCAPP immobilizated in crosslinked three-dimensional structure of EVA, enhancing the flame retardancy and electrical insulation properties of the EVA composites. After ageing test in hot water at 80°C for 2 weeks, the EVA/TPU/MCAPP composite with 180kGy could still maintain the UL-94 V-0 rating and the limiting oxygen index (LOI) value was as high as 30%. This investigation indicated the flame retardant EVA cable containing MCAPP could achieve stable properties and lower electrical fire hazard risk during long-term hot water ageing test.

Synergistic effects of pentaerythritol with aluminum hypophosphite in flame retardant ethylene‐vinyl acetate composites

The synergistic effects of pentaerythritol (PER) with aluminum hypophosphite (AHP) in halogen‐free flame retardant EVA/AHP/PER composites have been studied by cone calorimeter test (CCT), limiting oxygen index (LOI), vertical burning test (UL‐94), thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The data obtained from CCT show that the suitable amount of PER could considerably decrease the HRR and SPR values and prolong the combustion time of the EVA/AHP/PER composites. The results from LOI and UL‐94 show that a suitable amount of PER played synergistic effects on EVA/AHP/PER composites which increased the LOI value. The TGA data reveal that PER increased the char residues of the EVA/AHP/PER composites which made the EVA/AHP/PER composites have better thermal stability. SEM measurement results give positive evidence that the compact charred layers formed when 8 wt% AHP is substituted with PER and rich compact char layers could explain the excellent flame retardance. The mechanical properties results indicate that when AHP is substituted with a suitable amount PER, the tensile strength and elongation at break of EVA/AHP/PER composites can be maintained. POLYM. COMPOS., 39:2299–2306, 2018. © 2016 Society of Plastics Engineers

Synergistic effect of ammonium polyphosphate and triazine-based charring agent on the flame retardancy and combustion behavior of ethylene-vinyl acetate copolymer

Triazine-based charring agent poly(4,6-dichloro-N-hydroxyethyl-1,3,5-triazin-2-amine-1,6-diaminohexane) (CNCO-HA) with ammonium polyphosphate (APP) was chosen to prepare intumescent flame retardant ethylene-vinyl acetate copolymer (EVA) composites by melting blending. The synergistic effect of APP and CNCO-HA on the flame retardancy, combustion behavior and flame retardant mechanism of EVA are investigated. The flame retardant properties from limited oxygen index (LOI) and vertical burning test (UL-94) show that the intumescent flame retardant (IFR) shows the best effect when the mass ratio of APP to CNCO-HA is 3:2; and the LOI value of EVA/IFR composite reaches maximum value 30.9% with 30% IFR loading. When the IFR loading is only 20%, the flame retardancy of EVA/IFR still passes UL-94 V-0 rating with LOI value of 28.2%. The cone calorimeter test (CCT) results reveal that IFR clearly changes the combustion behavior of EVA and forms a char layer on the surface of the composites, consequently resulting in obvious reduction of the flammability and smoke production of EVA. The thermogravimetric analysis (TGA) and thermogravimetric analyzer coupled to a mass spectrometer (TGA/MS) results indicate that IFR improves char residue and side chain fragmentation is probably the dominant mechanism of thermal degradation. The morphology observed by digital photos and SEM demonstrate that IFR promotes to form the compact intumescent char layer. The LRS and FTIR results indicate that EVA/IFR forms more connected structures containing POP and POC bonds and polyaromatic structure.