Graphene oxide-filled multilayer coating to improve flame-retardant and smoke suppression properties of flexible polyurethane foam

Abstract

To reduce the flammability of flexible polyurethane (FPU) foams, the graphene oxide (GO) nanosheet filled coatings were deposited on the surface of the FPU foam via layer-by-layer (LbL) assembly method. This consisted of the preparation of the GO using the modified Hummers’ method. The coated FPU foams were then prepared by alternatively submerging the foam into a chitosan solution (0.5 %), a GO suspension (0.1 %), and an alginate solution (0.3 %) until the desired number of trilayers was deposited on the surface of the FPU foam. Scanning electron microscopic images showed that GO-filled coating was evenly distributed on the surface of substrate. Thermogravimetric analysis of the coated FPU foams suggested that the high mass of char residue can be obtained. The cone calorimeter test results of the coated FPU foams showed a reduction in the peak heat release rate (PHRR), peak smoke production rate (SPR), total smoke release (TSR), and peak carbon monoxide (CO) production can be obtained in comparison to the control. In particular, the sample assembled with 10 trilayers had a 8.31 wt % coating mass, which lead to a significant reduction in the peak HRR (59.9 %), peak SPR (45.6 %), TSR (30.5 %), and peak CO production (54.0 %). Such a significant improvement in flame retardancy suggested that the GO nanosheet is a good candidate as a flame-retardant LbL coating to reduce the flammability of FPU foam.