Posted on 30/01/2023 in Fire Safety
Phosphorus FRs and smoke toxicity.

Lab tests of six aryl phosphate FRs in PC/ABS show reduced fire hazard but increased smoke emission and fire gas toxicity. Six different aryl phosphate PIN FRs (TPP, CDP, RDP, BTPP, BDP and Sol-DP) were tested at 10% w/w loading in 8:1 PC/ABS, with also PTFE anti-drip agent. UL94 fire testing, cone calorimeter, NBS smoke chamber with FTIR and thermal decomposition (TGA) tests were carried out. The PIN FRs reduced fire hazard by preventing flame spread, reducing heat release (-13% to -25%) and delaying ignition. UL 94 V-0 (1.6 mm) was achieved in all but one case. However, smoke production, smoke opacity and emissions of toxic gases (CO, HCN, NOx) were increased with all six aryl phosphates. More stable aryl phosphates (e.g. RDP) tend to result in somewhat lower smoke toxicity than less stable molecules (e.g. TPP). The authors conclude that these aryl phosphate PIN FRs act in the gas phase, are thus effective in reducing fire hazard, but lead to release of incomplete combustion products, so smoke and toxic gases.

TPP = triphenyl phosphate. CDP = cresyl diPhenyl phosphate. RDP = resorcinol bis (diphenyl) phosphate. BTPP = butylated triphenyl phosphate. BDP = bisphenol A bis (diphenyl) phosphate. Sol-DP = fyroflex aryl phosphate.

“Effect of aryl phosphates on toxicity of combustion gases of flame-retardant polycarbonate/acrylonitrile butadiene styrene blends according to EN 45545 railway standard”, A. Sánchez & S. Villanueva, Fire and Materials, 2022, 1–11

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