Flexible polyurethane foams (FPUF) are easy to ignite and exhibit rapid flame spread. In this paper, the fire phenomena of two standard foam formulations containing tris(1,3‐dichloro‐2‐propyl) phosphate (FR‐2) and a halogen‐freepoly (ethyl ethylene phosphate) (PNX), respectively, as flame retardants are compared. A multi‐methodological approach is proposed which combines standard fire tests as well as new investigatory approaches. The thermophysical properties of the foams were determined by thermogravimetric analysis (TG), reaction to small flames was studied by means of the limiting oxygen index (LOI) and UL 94 HBF test, and the burning behavior was investigated with the cone calorimeter. Further, temperature development in burning cone calorimeter samples was monitored using thermocouples, and rheological measurements were performed on pyrolyzed material, delivering insight into the dripping behavior of the foams. This paper gives comprehensive insight into the fire phenomena of flame‐retarded FPUFs that are driven by the two‐step decomposition behavior of the foams. LOI and UL 94 HBF tests showed a reduced flammability and reduced tendency to drip for the flame‐retarded foams. TG and cone calorimeter measurements revealed that the two‐step decomposition behavior causes two stages during combustion, namely structural collapse and pool fire. The flame‐retardant mode of action was identified to take place primarily during the foam collapse and be based mainly on flame inhibition. However, some condensed‐phase action was been measured, leading to significantly increased melt viscosity and improved dripping behavior for foams containing PNX.

中文翻译：

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气泡和塌陷：阻燃的软质聚氨酯泡沫的着火现象

柔性聚氨酯泡沫（FPUF）易于点燃，火焰扩散迅速。在本文中，两种分别包含三（1,3-二氯-2-丙基）磷酸酯（FR-2）和无卤聚磷酸乙酯（PNX）作为阻燃剂的标准泡沫配方的着火现象比较。提出了一种多方法的方法，该方法结合了标准的耐火测试和新的调查方法。通过热重分析（TG）确定泡沫的热物理性质，通过极限氧指数（LOI）和UL 94 HBF试验研究对小火焰的反应，并用锥形量热仪研究燃烧行为。此外，使用热电偶监测燃烧的锥形量热计样品中的温度变化，在热解材料上进行流变学测量，从而深入了解泡沫的滴落行为。本文全面了解了阻燃FPUF的着火现象，这些现象是由泡沫的两步分解行为驱动的。LOI和UL 94 HBF测试表明，阻燃泡沫的可燃性降低，滴落趋势降低。TG和锥形量热仪的测量表明，燃烧过程中的两步分解行为导致两个阶段，即结构坍塌和池火。阻燃作用模式主要发生在泡沫破裂期间，并且主要基于火焰抑制作用。但是，我们测量了一些凝结作用，