Analysis of mechanical and flame‐retardant properties of flexible polyurethane foams

Abstract In this study, the mechanical and flame‐retardant properties of flexible polyurethane foams (FPUF) were analyzed as a function of the type of flame retardant. FPUF containing equal amounts of two halogenated flame retardants (tris 2‐cloropropyl phosphate [TCPP] and phosphinyl alkyl phosphate ester) and three halogen‐free flame retardants (melamine, melamine cyanurate, and expandable graphite) were considered. The foaming properties of these samples were analyzed by studying the rise time and settling rate using cup foaming. Square foaming was used to analyze the mechanical properties, including density, elongation, tensile strength, and tear strength. In addition, Fourier‐transform infrared spectroscopy was performed, and flame retardancy was evaluated using a horizontal flame test and the limited oxygen index. A cone calorimeter test was also performed to evaluate the combustion characteristics. In FPUF containing the same ratio of flame retardant (15% of the total polyol), the properties of urethane foam blended with expandable graphite were improved; the tensile strength of this blend is 20% higher than that of samples containing melamine, and its peak heat release showed a 70% reduction compared to that of samples containing TCPP. These findings provide valuable reference information for developing flame retardants for fire safety FPUF in the near future.