Journal of Thermal Analysis and Calorimetry

, Volume 134, Issue 3, pp 1505–1519 | Cite as

Preparation of a novel mono-component intumescent flame retardant for enhancing the flame retardancy and smoke suppression properties of epoxy resin

  • Long YanEmail author
  • Zhisheng Xu
  • Xinghua Wang
  • Nan Deng
  • Zhiyong Chu


A novel mono-component intumescent flame retardant named pentaerythritol phosphate melamine salt (PPMS)-functionalized expandable graphite (PPMS-EG) was synthesized and carefully characterized by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, scanning electron microscopy (SEM)–energy-dispersive X-ray spectrometry, and thermo-gravimetric (TG) analyses. Then, PPMS-EG was incorporated into epoxy resin (EP) to enhance fire safety. The flammability properties of EP composites were investigated by limiting oxygen index (LOI), UL94 vertical burning test, and cone calorimeter test. As expected, PPMS-EG imparts good flame retardancy to epoxy resin, and EP matrix with 20 mass% PPMS-EG passes the UL94 V-0 rating and the LOI value reaches 27.3%. Cone calorimeter test shows that the incorporation of PPMS-EG dramatically reduces the heat release and smoke production of EP, and the peak heat release rate and peak smoke production rate of EP composite with 15 mass% PPMS-EG are reduced by 68.7% and 46.3%, respectively, compared to those of EP. By comparison with either PPMS or expandable graphite, the same addition of PPMS-EG produces higher flame-retardant and smoke suppression efficiencies in EP matrix due to the formation of a more compact and intumescent char layer, as determined from digital photographs and SEM images. TG results show that PPMS-EG significantly enhances the thermal stability and char-forming ability of EP composites. Char residue analysis reveals that PPMS-EG positively contributes to the formation of more phosphorus-rich cross-linking char and aromatic char in the condensed phase, thus exhibiting a more thermally stable char against the release of heat and smoke. Overall, PPMS-EG can be used as a highly efficient mono-component intumescent flame retardant for preparing super flame-retarded EP composites.

Graphical abstract


Expandable graphite Mono-component intumescent flame retardant Epoxy resin Flammability Thermal behavior 



This work was supported by the National Natural Science Foundation of China (No. 51676210), the Hunan Provincial Natural Science Foundation of China (No. 2018JJ3668), the Postdoctoral Science Foundation of Central South University, and the Project funded by China Postdoctoral Science Foundation (No. 2017M612587).


  1. 1.
    Sut A, Greiser S, Jäger C, Schartel B. Synergy in flame-retarded epoxy resin. J Therm Anal Calorim. 2017;128(1):141–53.CrossRefGoogle Scholar
  2. 2.
    Qiu S, Wang X, Yu B, Feng X, Mu X, Yuen RKK, Hu Y. Flame-retardant-wrapped polyphosphazene nanotubes: a novel strategy for enhancing the flame retardancy and smoke toxicity suppression of epoxy resins. J Hazard Mater. 2017;325:327–39.CrossRefGoogle Scholar
  3. 3.
    Wang X, Hu Y, Song L, Xing W, Lu H, Lv P, Jie G. Flame retardancy and thermal degradation mechanism of epoxy resin composites based on a DOPO substituted organophosphorus oligomer. Polymer. 2010;51:2435–45.CrossRefGoogle Scholar
  4. 4.
    Khalili P, Tshai KY, Hui D, Kong I. Synergistic of ammonium polyphosphate and alumina trihydrate as fire retardants for natural fiber reinforced epoxy composite. Compos Part B Eng. 2017;114:101–10.CrossRefGoogle Scholar
  5. 5.
    Jiao C, Zhang C, Dong J, Chen X, Qian Y, Li S. Combustion behavior and thermal pyrolysis kinetics of flame-retardant epoxy composites based on organic-inorganic intumescent flame retardant. J Therm Anal Calorim. 2015;119:1759–67.CrossRefGoogle Scholar
  6. 6.
    Bourbigot S, Le Bras M, Duquesne S, Rochery M. Recent advances for intumescent polymers. Macromol Mater Eng. 2004;289:499–511.CrossRefGoogle Scholar
  7. 7.
    Zhao X, Gao S, Liu G. A THEIC-based polyphosphate melamine intumescent flame retardant and its flame retardancy properties for polylactide. J Anal Appl Pyrol. 2016;122:24–34.CrossRefGoogle Scholar
  8. 8.
    Zhang F, Sun W, Wang Y, Liu B. Influence of the pentaerythritol phosphate melamine salt content on the combustion and thermal decomposition process of intumescent flame-retardant ethylene-vinyl acetate copolymer composites. J Appl Polym Sci. 2015;132:42148.Google Scholar
  9. 9.
    Makhlouf G, Hassan M, Nour M, Abdel-Monem YK, Abdelkhalik A. Evaluation of fire performance of linear low-density polyethylene containing novel intumescent flame retardant. J Therm Anal Calorim. 2017;130:1031–41.CrossRefGoogle Scholar
  10. 10.
    Zhang P, He Y, Tian S, Fan H, Chen Y, Yan J. Flame retardancy, mechanical, and thermal properties of waterborne polyurethane conjugated with a novel phosphorous-nitrogen intumescent flame retardant. Polym Compos. 2017;38:452–62.CrossRefGoogle Scholar
  11. 11.
    Tang M, Qi F, Chen M, Sun Z, Xu Y, Chen X, Zhang Z, Shen R. Synergistic effects of ammonium polyphosphate and red phosphorus with expandable graphite on flammability and thermal properties of HDPE/EVA blends. Polym Advan Technol. 2016;27:52–60.CrossRefGoogle Scholar
  12. 12.
    Alongi J, Han Z, Bourbigot S. Intumescence: tradition versus novelty. A comprehensive review. Prog Polym Sci. 2015;51:28–73.CrossRefGoogle Scholar
  13. 13.
    Wang X, Kalali EN, Wan J, Wang D. Carbon-family materials for flame retardant polymeric materials. Prog Polym Sci. 2017;69:22–46.CrossRefGoogle Scholar
  14. 14.
    Li Y, Zou J, Zhou S, Chen Y, Zou H, Liang M, Luo W. Effect of expandable graphite particle size on the flame retardant, mechanical, and thermal properties of water-blown semi-rigid polyurethane foam. J Appl Polym Sci. 2014;131(3):1082–90.Google Scholar
  15. 15.
    Luo W, Li Y, Zou H, Liang M. Study of different-sized sulfur-free expandable graphite on morphology and properties of water-blown semi-rigid polyurethane foams. RSC Adv. 2014;4:37302–10.CrossRefGoogle Scholar
  16. 16.
    Laachachi A, Burger N, Apaydin K, Sonnier R, Ferriol M. Is expanded graphite acting as flame retardant in epoxy resin? Polym Degrad Stabil. 2015;117:22–9.CrossRefGoogle Scholar
  17. 17.
    Yang S, Wang J, Huo S, Wang M, Wang J, Zhang B. Synergistic flame-retardant effect of expandable graphite and phosphorus-containing compounds for epoxy resin: strong bonding of different carbon residues. Polym Degrad Stabil. 2016;128:89–98.CrossRefGoogle Scholar
  18. 18.
    Wang N, Xu G, Wu Y, Zhang J, Hu L, Luan H, Fang Q. The influence of expandable graphite on double-layered microcapsules in intumescent flame-retardant natural rubber composites. J Therm Anal Calorim. 2016;123:1239–51.CrossRefGoogle Scholar
  19. 19.
    Xi W, Qian L, Huang Z, Cao Y, Li L. Continuous flame-retardant actions of two phosphate esters with expandable graphite in rigid polyurethane foams. Polym Degrad Stabil. 2016;130:97–102.CrossRefGoogle Scholar
  20. 20.
    Zheng Z, Liu Y, Zhang L, Wang H. Synergistic effect of expandable graphite and intumescent flame retardants on the flame retardancy and thermal stability of polypropylene. J Mater Sci. 2016;51:5857–71.CrossRefGoogle Scholar
  21. 21.
    Liu Y, He J, Yang R. Effects of Dimethyl Methylphosphonate, Aluminum hydroxide, ammonium polyphosphate, and expandable graphite on the flame retardancy and thermal properties of polyisocyanurate-polyurethane foams. Ind Eng Chem Res. 2015;54:5876–84.CrossRefGoogle Scholar
  22. 22.
    Zhu H, Zhu Q, Li J, Tao K, Xue L, Yan Q. Synergistic effect between expandable graphite and ammonium polyphosphate on flame retarded polylactide. Polym Degrad Stabil. 2011;96:183–9.CrossRefGoogle Scholar
  23. 23.
    Han J, Liang G, Gu A, Ye J, Zhang Z, Yuan L. A novel inorganic-organic hybridized intumescent flame retardant and its super flame retarding cyanate ester resins. J Mater Chem A. 2013;1:2169–82.CrossRefGoogle Scholar
  24. 24.
    Chen X, Zhuo J, Song W, Jiao C, Qian Y, Li S. Flame retardant effects of organic inorganic hybrid intumescent flame retardant based on expandable graphite in silicone rubber composites. Polym Adv Technol. 2014;25:1530–7.CrossRefGoogle Scholar
  25. 25.
    Liu D, Zhong X, Shi X, Qi Y, Zhu T, Shao M, Zhang F. Pentaerythritol phosphate melamine salt, a new aggregating reagent for oilfield chemical sand control: preparation, properties, and mechanism. Energy Fuel. 2016;30:2503–13.CrossRefGoogle Scholar
  26. 26.
    Fontaine G, Bourbigot S, Duquesne S. Neutralized flame retardant phosphorus agent: facile synthesis, reaction to fire in PP and synergy with zinc borate. Polym Degrad Stabil. 2008;93(1):68–76.CrossRefGoogle Scholar
  27. 27.
    Wang G, Yang J. Influences of expandable graphite modified by polyethylene glycol on fire protection of waterborne intumescent fire resistive coating. Surf Coat Technol. 2010;204:3599–605.CrossRefGoogle Scholar
  28. 28.
    Huang G, Chen S, Tang S, Gao J. A novel intumescent flame retardant-functionalized graphene: nanocomposite synthesis, characterization, and flammability properties. Mater Chem Phys. 2012;135:938–47.CrossRefGoogle Scholar
  29. 29.
    Wang P, Yang F, Cai Z. Synergistic effect of organo-montmorillonite and DOPO-based oligomer on improving the flame retardancy of epoxy thermoset. J Therm Anal Calorim. 2017;128:1429–41.CrossRefGoogle Scholar
  30. 30.
    Yan L, Xu Z, Wang X. Influence of nano-silica on the flame retardancy and smoke suppression properties of transparent intumescent fire-retardant coatings. Prog Org Coat. 2017;112:319–29.CrossRefGoogle Scholar
  31. 31.
    Ye L, Meng X, Ji X, Li Z, Tang J. Synthesis and characterization of expandable graphite-poly(methyl methacrylate) composite particles and their application to flame retardation of rigid polyurethane foams. Polym Degrad Stabil. 2009;94:971–9.CrossRefGoogle Scholar
  32. 32.
    Si M, Feng J, Hao J, Xu L, Du J. Synergistic flame retardant effects and mechanisms of nano-Sb2O3 in combination with aluminum phosphinate in poly(ethylene terephthalate). Polym Degrad Stabil. 2014;100:70–8.CrossRefGoogle Scholar
  33. 33.
    Xu Z, Yan L, Liu D, Ni T, Peng J, Xu Y. Correlations between measurements of flame-retarded high-density polyethylene composites subjected to three conventional fire tests. In: Harada K, Matsuyama K, Himoto K, Nakamura Y, Wakatsuki K, editors. Fire science and technology 2015. Singapore: Springer; 2017. p. 599–607.CrossRefGoogle Scholar
  34. 34.
    Yang A, Deng C, Chen H, Wei Y, Wang Y. A novel Schiff-base polyphosphate ester: highly-efficient flame retardant for polyurethane elastomer. Polym Degrad Stabil. 2017;144:70–82.CrossRefGoogle Scholar
  35. 35.
    Shi Y, Yu B, Zheng Y, Guo J, Chen B, Pan Z, Hu Y. A combination of POSS and polyphosphazene for reducing fire hazards of epoxy resin. Polym Adv Technol. 2018;29(4):1242–54.CrossRefGoogle Scholar
  36. 36.
    Li H, Hu Z, Zhang S, Gu X, Wang H, Jiang P, Zhao Q. Effects of titanium dioxide on the flammability and char formation of water-based coatings containing intumescent flame retardants. Prog Org Coat. 2015;78:318–24.CrossRefGoogle Scholar
  37. 37.
    Xu Z, Chu Z, Yan L. Enhancing the flame-retardant and smoke suppression properties of transparent intumescent fire-retardant coatings by introducing boric acid as synergistic agent. J Therm Anal Calorim. 2018;133:1241–1252.CrossRefGoogle Scholar
  38. 38.
    Murat Unlu S, Tayfun U, Yildirim B, Dogan M. Effect of boron compounds on fire protection properties of epoxy based intumescent coating. Fire Mater. 2017;41(1):17–28.CrossRefGoogle Scholar
  39. 39.
    Yan L, Xu Z, Wang X. Synergistic effects of organically modified montmorillonite on the flame-retardant and smoke suppression properties of transparent intumescent fire-retardant coatings. Prog Org Coat. 2018;122:107–18.CrossRefGoogle Scholar
  40. 40.
    Guan Y, Huang J, Yang J, Shao Z, Wang Y. An effective way to flame-retard biocomposite with ethanolamine modified ammonium polyphosphate and its flame retardant mechanisms. Ind Eng Chem Res. 2015;54:3524–31.CrossRefGoogle Scholar
  41. 41.
    Yuan B, Fan A, Yang M, Chen X, Hu Y, Bao C, Jiang S, Niu Y, Zhang Y, He S, Dai H. The effects of graphene on the flammability and fire behavior of intumescent flame retardant polypropylene composites at different flame scenarios. Polym Degrad Stabil. 2017;143:42–56.CrossRefGoogle Scholar
  42. 42.
    Wang P, Xia L, Jian R, Ai Y, Zheng X, Chen G, Wang J. Flame-retarding epoxy resin with an efficient P/N/S-containing flame retardant: preparation, thermal stability, and flame retardance. Polym Degrad Stabil. 2018;149:69–77.CrossRefGoogle Scholar

Copyright information

© Akadémiai Kiadó, Budapest, Hungary 2018

Authors and Affiliations

  1. 1.Institute of Disaster Prevention Science and Safety TechnologyCentral South UniversityChangshaChina
  2. 2.School of Civil EngineeringCentral South UniversityChangshaChina

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