Preparation of a Novel Composite Coating of APP/MMT/APTES on Polyurethane with Improved Flame-Retarding Performance

An environmentally friendly flame retardant coating for polyurethane composed of ammonium polyphosphate(APP)/montmorillonite(MMT)/(3-aminopropyl)triethoxysilane(APTES) has been prepared by deposition on a polyurethane surface through a one-step immersion, enhancing its flame retardancy. The coating of APP/MMT/APTES on the polyurethane sample surface has been verified from XPS and FTIR analysis. In comparison to untreated polyurethane, the amount of char residue after combustion of the flame-retardant polyurethane increases significantly, with a 50.8% increase in limiting oxygen index (LOI). The cone calorimetry test shows that the peak heat release rate (PHRR) and total smoke production (TSP) decreased by 80.28% and 66.7%, respectively. The formation of a dense carbon layer on the polyurethane surface restricts heat feedback from the combustion zone and reduces emission of volatiles. The preparation of polyurethane flame retardant coatings is carried out in an aqueous solution; the process is environmentally friendly and an attractive technology for polymer flame retarding.