Research on the flame-retardant mechanism of a new-type polyurethane coating system

The flame-retardant (FR) mechanism resulting from an intumescent system of the FR formulation: polyurethane polymer/ammonium polyphosphate/triazine carbonific (PU/APP/Carbonific) was studied. The FR properties (LOI) of the system were strongly improved in comparison with the system PU. The FR mechanism of the system 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 ¹³C) spectroscopy. 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.