Fabrication of binary hybrid-filled layer-by-layer coatings on flexible polyurethane foams and studies on their flame-retardant and thermal properties

Abstract

A binary hybrid-filled flame-retardant coating, consisting of graphene oxide (GO) and amino-terminated silica nanospheres (KH-550-SiO₂), was fabricated onto a flexible polyurethane (FPU) foam using the layer-by-layer assembly method. The coexistence morphology between GO nanosheets with KH-550-SiO₂, as a percolated network structure, can be observed on the FPU foam surface as shown by the scanning electron microscopy images. The comparative cone test study revealed that the binary hybrid-filled coating had a larger reduction in peak heat release rate (PHRR) (50.9% reduction) and could eliminate the second PHRR for FPU foams compared with the single (GO or KH-550-SiO₂)-filled coating. Such an obvious improvement in flame-retardancy for FPU foam could be ascribed to the barrier effect of the binary hybrid network structure formed, which can reduce the amounts of organic volatiles available for burning, and the heat and oxygen transfers between the flame and underlying foam.