Layered double hydroxide-decorated flexible polyurethane foam: significantly improved toxic effluent elimination

Abstract

A layered double hydroxide-based fire-blocking coating was deposited on the surface of a flexible polyurethane foam using a layer-by-layer method to improve its thermal stability, flame retardancy and smoke suppression properties. The assembly process was carried out by alternately submerging a flexible polyurethane foam into chitosan solution, layered double-hydroxide suspension and alginate solution. Analysis of the cone calorimeter data indicated that all the coated flexible polyurethane foam showed a lower peak heat release rate (pHRR), total heat release (THR), peak smoke production rate (pSPR), total smoke release (TSR), peak carbon monoxide (CO) level and peak carbon dioxide (CO₂) level compared with the control flexible polyurethane foam. Such a significant improvement in flame retardancy and smoke suppression and a decrease in toxic gas release was ascribed to the physical barrier effect of the layer by layer structure. At the same number of layers, a nickel-aluminum layered double-hydroxide-containing coating performs better than a magnesium-aluminum layered double-hydroxide-filled coating with respect to elimination of toxic effluents from FPUFs.