Ignition, combustion, toxicity, and fire retardancy of polyurethane foams: A comprehensive review

Abstract

This review provides insight into the ignition, combustion, smoke, toxicity, and fire-retardant performance of flexible and rigid polyurethane foams. This review also covers various additive and reactive fireretardant approaches adopted to render polyurethane foams fire-retardant. Literature sources are mostly technical publications, patents, and books published since 1961. It has been found by different workers that polyurethane foams are easily ignitable and highly flammable, support combustion, and burn quite rapidly. They are therefore required to be fire-retardant for different applications. Polyurethane foams during combustion produce a large quantity of vision-obscuring smoke. The toxicity of the combustion products is much higher than that of many other manmade polymers because of the high concentrations of hydrogen cyanide and carbon monoxide. Polyurethane foams have been rendered fire-retardant by the incorporation of phosphorus-containing compounds, halogen-containing compounds, nitrogen-containing additives, silicone-containing products, and miscellaneous organic and inorganic additives. Some heat-resistant groups such as carbodiimide-, isocyanurate-, and nitrogencontaining heterocycles formed with polyurethane foams also render urethane foams fire-retardant. Fire-retardant additives reduce the flammability, smoke level, and toxicity of polyurethane foams with some degradation in other characteristics. It can be concluded that despite many significant attempts, no commercial solution to the fire retardancy of polyurethane foams without some loss of physical and mechanical properties is available.

Investigating the influence of conduit residues on polyurethane plates

“…At 325.00 °C, the mass loss was 45.43%, and complete degradation occurred at 770 °C. The first and second PU decomposition steps correspond to urethane bond-breaking and polyol decomposition, respectively [8,39,50,51] .…”

“…Furthermore, Mancini et al [2,[5][6][7] claims that plastics have low biodegradability and occupy a large amount of space, decreasing the useful life of landfill areas. The effects of degradation can appear after 20-30 years [5,8] . Building companies are improving their construction techniques and optimizing proper waste disposal to meet the current Brazilian legislation (CONAMA Resolution No.…”

“…Polyurethane is a thermoplastic polymer often used in construction works due to its excellent performance as thermal and acoustic insulation [7,8,[13][14][15][16][17] . The physico-chemical properties of polyurethane are important for that purpose [5] .…”

“…The material has suitable mechanical strength to be used as thermal insulation in applications such as precast insulated sandwich wall panels, in ceiling lining or floors, and inside wood frame walls [18][19][20][21] . Singh [8] , however, warns that this is not suitable for surface coating and interior finishes in buildings because it is not resistant to fire. The ignition of polyurethane foams includes all gas-phase processes that occur between the fuel production step and the occurrence of a visible hot flame.…”

“…The ignition of polyurethane foams occurs by the interdiffusion of the flammable gases with air. The basic physical and chemical aspects of gas-phase ignition reactions have been studied by several researchers [7,8,22] . Thus, the introduction of flame retardants is required in those situations [7,8,16,23] .…”