7. Intumescent systems

Intumescent systems swell under thermal irradiation, as shown in figure 3 . The material is then protected from the heat flow by a cellular layer with low thermal conductivity. This protective cellular layer also reduces the rate of diffusion of pyrolysis gases from the polymer into the combustion zone, as well as the rate of material degradation. Chemically speaking, the polymer or its degradation products may subsequently react with certain components of the flame retardant. The formulation of this type of protection includes a source of inorganic acid, a polyhydric compound and blowing agents.