Six different phosphorus-containing polyols were synthesised from bio-based derivatives of castor oil, soybean oil, sucrose and orange peel, by reacting with DEAP (diethyl allyphosphonate, derived from triethyl phosphite) and 1-thio glycerol (TG). Rigid bio-based polyurethane foams were produced by reaction with isocyanate. The presence of phosphorus-containing polyols (1.5% wt. phosphorus) did not significantly modify foam characteristics (closed cell content, morphology) and enabled to achieve appropriate density, whilst reducing self-extinguishing time by over fifty times (reduced to <2 seconds for 12.5 mm thick sample after 10 seconds open flame) and mass loss in combustion by sixteen times (compared to foam with no phosphorus content). The improved fire performance was related to generation of a surface protecting char layer on the foam. The phosphorus content also showed to reduce total smoke emission (TSR) and smoke release rate (TSR reduced by nearly one half with 1.5% P wt.).
“Sustainable flame-retardant polyurethanes using renewable resources”, S. Bhoyate et al., Industrial Crops & Products 123 (2018) 480–488 https://doi.org/10.1016/j.indcrop.2018.07.025