Study on pyrolysis characteristics, kinetics and flame-retardant mechanism of ultra-thin intumescent fire-retardant coating for steel structures by thermogravimetric analysis and shuffled complex evolution

As one of the most effective fire prevention measures, the ultra-thin intumescent fire-retardant coating (IFRC) is widely used to coat the surface of steel structure in buildings. The aim of this work was to investigate the pyrolysis characteristics, kinetics and flame-retardant mechanism of ultra-thin IFRC for dealing with the fire hazards of steel structures. Thermogravimetric experiments were carried out at multiple heating rates. The thermogravimetric analysis results showed that the whole thermal degradation process could be divided into two stages. In Stage I, the active filler and resin released H2O and other small molecules with the mass loss of 10%. Stage II was assigned to the intramolecular and intermolecular reactions of the matrix resin, catalyst, carbon forming agent and foaming agent in the ultra-thin IFRC, which released the flame-retardant gases NH3, H2O and CO2. The initial kinetic parameters were obtained by the model-free method, and then the shuffled complex evolution (SCE) algorithm was used to optimize these proposed kinetic parameters. Moreover, the predicted pyrolysis curves based on optimized kinetic parameters were compared with experimental data, and the good agreement was achieved. Eventually, the flame-retardant mechanism in different stages was speculated, which could provide the basis and reference for the development and application of the ultra-thin IFRC.