Relationship between the thermal degradation chemistry and flammability of commercial flexible polyurethane foams

Abstract

In this article, we report the use of a variety of analytical methods, in particular, solid-state 1H-NMR and 13C-NMR to characterize the relationship between the condensed-phase chemistry and burning behavior as determined by a series of combustion tests for two commercially derived flexible polyurethane foams, one combustion-modified. The combustion tests showed that the foams met several regulatory requirements in terms of their fire performance, whether or not they were combustion-modified. Both foams passed the MV SS 302 and CAL 117 small-flame tests. The nonmodified foam failed the Crib 5 test, but this test had a much larger ignition source. The particular problem with the nonmodified foam was melt drip into the flame zone. This led to a steady maintenance of the fuel feed and a rapid escalation of the fire. In contrast, the combustion-modified foam showed little melt drip and self-extinguished. Thermal analysis data for the two foams showed that melamine acted in part as an endothermic heat sink. This alone did not account for the much reduced melt flow and drip of the combustion-modified foam, but the solid-state 1H-NMR data clearly showed that the molecular mobility of the combustion char from combustion-modified foam was lower than the unmodified foam char, which indicated that the flame-retardant formulation in the combustion-modified foam acted by a condensed-phase mechanism

Thermophysical properties of polyurethane foams and their melts

“…This result supports the manufacturer's information where FR-G-32 only contains halophosphate as FR additive that predominantly performs in the gas phase. FR-Y-36 and FR-LG-38 have a higher nitrogen content than the other foams in Table I, and this is an indication of the presence of melamine [27] as reported by the manufacturer. Good agreement is found between the chemical composition of polyurethane foams used in this research and those reported in the literature [28][29][30].…”

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

“…[16][17][18] The thermal degradation process and its relation to foam ignition have been studied with a variety of analytical and existing fire-test methods. [19][20][21][22] The thermal stability and ignition of a conventional polyurethane foam mainly depend on the composition. 23 When a polyurethane foam is subjected to heat, various polyurethane linkages are broken at different temperatures.…”

Intrinsic flame resistance of polyurethane flexible foams: Unexpectedly low flammability without any flame retardant

“…The LOI value of the MDI‐PUR‐FF is unexpectedly high for flame‐retardant‐free PUR‐FFs. Typically, LOI values are in the range of 17.0 O 2 % to 21.3 O 2 % . Both MDI‐based PUR‐FFs burn with high melt flow, but only the AIRCRAFT‐PUR‐FF shows burning drops.…”