How do flame retardant solutions affect the combustion process of materials, especially during the pyrolysis, ignition and flame propagation stages?

Flame retardant solutions have a significant impact on the combustion process of materials, especially during the three critical stages of pyrolysis, ignition and flame propagation.

1. Pyrolysis stage
Pyrolysis is the initial stage of the material combustion process and involves the chemical decomposition of the material at high temperatures. Flame retardant solutions affect the pyrolysis stage in several ways:
Increase pyrolysis temperature: Flame retardants absorb heat and increase the material's pyrolysis temperature, requiring higher external temperatures to initiate the material's pyrolysis reaction. This reduces the likelihood of the material pyrolyzing at lower temperatures.
Reduce the pyrolysis rate: Flame retardants can catalyze the pyrolysis process of the material, reducing its pyrolysis rate. This means that even at high temperatures, the material will pyrolyze more slowly, reducing the production of flammable gases.
Increase remaining carbon: Flame retardants can cause the material to produce more solid carbonization instead of flammable gases during the pyrolysis process. These chars cover the surface of the material and form a protective layer, further inhibiting the progress of the pyrolysis reaction.

2. Fire stage
Ignition is a critical stage in the material combustion process and involves the mixing of flammable gases with oxygen and reaching a temperature to initiate combustion. The impact of flame retardant solutions during the fire stage is mainly reflected in:
Inhibiting free radical chain reactions: Flame retardants can capture free radicals in combustion reactions, such as OH radicals, thereby interrupting the free radical chain reaction and preventing the initiation of flames.
Reduce combustion temperature: Flame retardants release non-combustible gases during the combustion process. These gases can lower the temperature of the burning area and make it difficult to maintain the flame.

3. Flame propagation stage
Flame propagation is the final stage of the combustion process and involves the spread and spread of flame across the surface of a material. The impact of flame retardant solutions during the flame propagation stage mainly includes:
Form a protective layer: Flame retardants will melt, vaporize or form a carbonized layer at high temperatures, covering the surface of the material. This protective layer blocks the transfer of heat and oxygen, slowing the spread of flames.
Reduce the heat release rate: Flame retardants can reduce the heat release rate of the material, reduce the burning intensity of the flame, and slow down the spread of the flame.
To sum up, flame retardant solutions have significant effects on the combustion process of materials by increasing pyrolysis temperature, reducing pyrolysis rate, increasing residual carbon, inhibiting free radical chain reactions, reducing combustion temperature and forming protective layers. effects, especially in the three critical stages of pyrolysis, ignition and flame propagation. These effects work together to make flame retardant materials show better flame retardant properties in fires.