Flame-retardant mechanism resulting from an intumescent system

In this work, we studied the flame-retardant (FR) mechanism resulting from an intumescent phenomenon of the FR formulation: polyurethane polymer/ammonium polyphosphate/triazine carbonific (PU/APP/Carbonific). The FR properties (LOI and cone calorimeter) of the system were strongly improved in comparison with the PU and PU/APP systems. Characterization of the FR mechanism of the system PU/APP/Carbonific was carried out using scanning electron microscopy (SEM), elemental analysis (ELA), Fourier transform infrared spectroscopy (FTIR), and magic-angle spinning nuclear magnetic resonance (MAS-NMR C-13) spectroscopy of the solid state. The study shows the formation of organic phosphocarbonaceous esters, aromatic materials, and triazine-containing chars, which participate in the improvement of the fire-retardant properties of the system.