Predicting the fire performance of intumescent fire-retardant coating with inert and oxidative reaction schemes

Accurate evaluation of the performance of Intumescent fire-retardant coating (IFRC) is critical for predicting fire behavior in protected construction. In this work, the pyrolysis performance of IFRC is characterized in both N₂ and air. Comprehensive models based on ThermaKin are developed. A seven-step inert reaction and eight-step oxidative reaction schemes are proposed to describe the pyrolysis of IFRC in N₂ and air. The corresponding kinetic and thermodynamic model parameters are obtained by inversely analyzing the measurements. The obtained comprehensive models are used to simulate the experimental results of cone calorimeter. Both model simulations capture the trend of mass loss rate (MLR) curves. However, the simulation with oxidative reaction scheme presents a faster initial MLR increase rate, higher MLR peak (MLR_peak) and earlier time to MLR_peak with higher R² of 0.91, 0.95 and 0.85 (for the dry film thickness of 1.00 mm, 2.00 mm and 3.00 mm). This is due to the exothermic reactions in air accelerating the IFRC pyrolysis, while the endothermic reactions in N₂ decelerating the IFRC pyrolysis. The model with an oxidative reaction scheme can better predict the performance of IFRC in real-fire scenarios, which may contribute to the evaluation of IFRC in the construction fire design.