The effects of N,N -(pyromellitoyl)-bis-l-phenylalanine diacid ester glycol on the flame retardancy and physical–mechanical properties of rigid polyurethane foams

Abstract

Flame-retardant rigid polyurethane foams incorporating N,N-(pyromellitoyl)-bis-l-phenylalanine diacid ester glycol have been prepared. After adding N,N-(pyromellitoyl)-bis-l-phenylalanine diacid ester glycol, the density and compressive strength of the polyurethane foams were seen to decrease. The flame retardancy of the polyurethane foams has been characterized by limiting oxygen index, upper limit–94, and cone calorimeter tests. The polyurethane foam with 2.27 wt% N,N-(pyromellitoyl)-bis-l-phenylalanine diacid ester glycol gave a highest limiting oxygen index of 33.4%, and the peak heat release rate of polyurethane foam reduced to 19.5 kW/m² from 47.6 kW/m² of PU-0 without N,N-(pyromellitoyl)-bis-l-phenylalanine diacid ester glycol. Upper limit–94 revealed N,N-(pyromellitoyl)-bis-l-phenylalanine diacid ester glycol did not change the burning rating, and all polyurethane foams had passed V-0 rating. The thermal stability of polyurethane foams has been investigated by thermogravimetric analyzer. N,N-(pyromellitoyl)-bis-l-phenylalanine diacid ester glycol significantly increased the initial decomposition temperature of polyurethane foams and their residues. In addition, the morphology of residual char from the flame-retarded polyurethane foams after cone calorimeter tests has also been characterized by digital photographs. The results indicated that N,N-(pyromellitoyl)-bis-l-phenylalanine diacid ester glycol significantly enhanced the strength and compatibility of the char layer formed by the polyurethane foams. These results indicate that N,N-(pyromellitoyl)-bis-l-phenylalanine diacid ester glycol can improve both the quality and quantity of the char, which has a significant effect on the flame-retardant properties of the foam.

Keywords

Rigid polyurethane foams flame retardancy thermal properties

Get full access to this article

View all access options for this article.

References

Zatorski

Brzozowski

Kolbrecki

New developments in chemical modification of fire-safe rigid polyurethane foams. Polym Degrad Stab 2008; 93(11): 2071–2076.

Levchik

Weil

. Thermal decomposition, combustion and fire-retardancy of polyurethanes—a review of the recent literature. Polym Int 2004; 53(11): 1585–1610.

Chattopadhyay

Webster

DC.

Thermal stability and flame retardancy of polyurethanes. Prog Polym Sci 2009; 34(10): 1068–1133.

Kulesza

Pielichowski

Thermal decomposition of bisphenol A—based polyether urethanes blown with pentane part II—influence of the novel NaH2PO4/NaHSO4 flame retardant system. J Anal Appl Pyrolysis 2006; 76(1–2): 249–253.

Patrick

Sottos

White

SR.

Microvascular based self-healing polymeric foam. Polymer 2012; 53(19): 4231–4240.

König

Kroke

Flame retardancy working mechanism of methyl-DOPO and MPPP in flexible polyurethane foam. Fire Mater 2012; 36(1): 1–15.

Chen

Shao

Wang

et al . Halogen-free flame-retardant flexible polyurethane foam with a novel nitrogen-phosphorus flame retardant. Ind Eng Chem Res 2012; 51(29): 9769–9776.

Sonnenschein

Wendt

BL.

Design and formulation of soybean oil derived flexible polyurethane foams and their underlying polymer structure/property relationships. Polymer 2013; 54(10): 2511–2520.

Usta

Investigation of fire behavior of rigid polyurethane foams containing fly ash and intumescent flame retardant by using a cone calorimeter. J Appl Polym Sci 2012; 124(4): 3372–3382.

10.

Kim

Seo

Lee

et al . Effect of flame retardants on flame retardancy of rigid polyurethane foam. J Korean Inst Gas 2013; 17(5): 75–80.

11.

Zatorski

Brzozowski

Lebek

Production of PUR and PUR-PIR foams with red phosphorus as a flame retardant. Polimery 2005; 50(9): 686–689.

12.

Duquesne

Bras

Bourbigot

et al . Mechanism of fire retardancy of polyurethanes using ammonium polyphosphate. J Appl Polym Sci 2001; 82(13): 3262–3274.

13.

Thirumal

Khastgir

Nando

et al . Halogen-free flame retardant PUF: effect of melamine compounds on mechanical, thermal and flame retardant properties. Polym Degrad Stab 2010; 95(6): 1138–1145.

14.

Chen

Zhao

Yan

et al . Preparation and properties of halogen-free flame retardant polyurethane foams. Adv Mater Res 2012; 418–420: 540–543.

15.

Thirumal

Singha

Khastgir

et al . Halogen-free flame-retardant rigid polyurethane foams: effect of alumina trihydrate and triphenylphosphate on the properties of polyurethane foams. J Appl Polym Sci 2010; 116(4): 2260–2268.

16.

Chen

Huo

Jiao

et al . TG/FTIR characterization of volatile compounds from flame retardant polyurethane foam materials. J Anal Appl Pyrolysis 2013; 100: 186–191.

17.

Zhang

et al . Synergistic effects of hydroxides and dimethyl methylphosphonate on rigid halogen-free and flame-retarding polyurethane foams. J Appl Polym Sci 2013; 128(1): 347–353.

18.

Lorenzetti

Modesti

Gallo

et al . Synthesis of phosphinated polyurethane foams with improved fire behaviour. Polym Degrad Stab 2012; 97(11): 2364–2369.

19.

Bian

Tang

et al . Dependence of flame-retardant properties on density of expandable graphite filled rigid polyurethane foam. J Appl Polym Sci 2007; 104(5): 3347–3355.

20.

Thirumal

Khastgir

Singha

et al . Effect of expandable graphite on the properties of intumescent flame-retardant polyurethane foam. J Appl Polym Sci 2008; 110(5): 2586–2594.

21.

Shi

Xie

et al . Flame retardancy of different-sized expandable graphite particles for high-density rigid polyurethane foams. Polym Int 2006; 55(8): 862–871.

22.

Wolska

Gozdzikiewicz

Ryszkowska

Thermal and mechanical behavior of flexible polyurethane foams modified with graphite and phosphorus fillers. J Mater Sci 2012; 47(15): 5627–5634.

23.

Liu

Yang

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(22): 5876–5884.

24.

Wang

Yang

Wang

YZ.

Physical and chemical effects of diethyl N,N′-diethanol aminomethyl phosphate on flame retardancy of rigid polyurethane foam. J Appl Polym Sci 2001; 82(2): 276–282.

25.

Chen-Yang

Yuan

et al . Preparation and characterization of novel flame retardant (aliphatic phosphate) cyclotriphosphazene-containing polyurethanes. J Appl Polym Sci 2003; 90(5): 1357–1364.

26.

Yuan

Chen

Tsai

et al . Thermally stable and flame-retardant aromatic phosphate and cyclotriphosphazene-containing polyurethanes: synthesis and properties. Polym Adv Technol 2005; 16(5): 393–399.

27.

Chen

Tan

et al . Inherent flame-retardant flexible polyurethane foam with low content of phosphorus-containing cross-linking agent. J Ind Eng Chem Res 2014; 53(3): 1160–1171.

28.

Tang

et al . Synthesis and characterization of thermally stable poly(urethane–imide)s based on novel diols-containing imide and alkynyl groups. High Perform Polym 2013; 25(7): 798–812.