Aluminium diethylphosphinate was tested at 0 – 11 % loading in rigid polyurethane foam (PUR), produced by one-step mixing, water blowing. Fire performance and combustion behaviour were analysed. Dosing of AlPi was noted to deteriorate the foam cell structure. AlPi improved fire behaviour, for example reducing by nearly 50% burning time in the UL94 vertical burn test (achieving UL94-V1 even with low AlPi loading), increasing LOI by nearly one quarter and decreasing peak heat release rate by one fifth (compared to neat PUR). AlPi also reduced hydrocarbons and carbon monoxide emissions during burning. Analysis showed that AlPi caused PUR to form aromatic and aromatic heterocyclic structures in heat decomposition, so improving the strength and compactness of char, in addition to acting to inhibit fire in the gas phase.
“Effect of aluminum diethylphosphinate on flame retardant and thermal properties of rigid polyurethane foam composites”, G. Tang et al., Journal of Thermal Analysis and Calorimetry https://doi.org/10.1007/s10973-019-08897-z