Flame retardant mechanism of ATH

Regarding the flame retardant mechanism of aluminium hydroxide, the description of its flame retardant process is not very consistent due to the different categories of polymers. However, with the progress of research, it is mostly believed that the flame retardant effect of aluminium hydroxide is the result of the synergistic effect of several mechanisms.

The flame retardant mechanism can be summarised as follows: 

(1) Heat absorption. Dehydration at 200-350℃ absorbs heat and inhibits the heating of the polymer.

(2) Dilution. Aluminium hydroxide fills the polymer and reduces the concentration of combustible polymers. The water vapour released by the dehydration of aluminium hydroxide dilutes the concentration of flammable gases and oxygen, preventing combustion.

(3) Covering effect. The dehydration of aluminium hydroxide produces a protective film of Al2O3 on the surface of the combustible material, insulating it from combustion. The protective film of alumina, isolated from oxygen, can prevent further combustion. 

 4) Carbonisation. The flame retardant produces a strong dehydrating substance under burning conditions, making the plastic carbonised and less likely to produce combustible volatiles, thus preventing the spread of flame.