What combustion byproducts will polymer flame retardants produce at high temperatures?

Polymer flame retardants can produce various combustion byproducts at high temperatures depending on their chemical composition. Here are some examples of combustion byproducts from different types of flame retardants:

Halogenated Flame Retardants (e.g., Bromine or Chlorine-based):
When halogenated flame retardants decompose at high temperatures, they can produce hydrogen halides (such as HBr or HCl), which are acidic gases that can contribute to the formation of harmful and corrosive substances like halonic acids when they come into contact with atmospheric moisture.

Phosphorus-based Flame Retardants:
Phosphorus-containing flame retardants may produce phosphoric acid (H3PO4) and polyphosphoric acid when they decompose. These can form a protective char layer that helps to insulate the material below from the heat source.

Inorganic Hydroxides (e.g., Aluminum Hydroxide, Magnesium Hydroxide):
Inorganic hydroxides like aluminum hydroxide (ATH) and magnesium hydroxide (MDH) decompose endothermically to release water vapor (H2O) and form stable metal oxides (Al2O3, MgO). This process can help to cool the material and reduce the release of flammable volatiles.

Silicon-based Flame Retardants:
Silicon compounds, as a newer class of flame retardants, can produce silicon oxide (SiO2) and other silicate materials when they decompose. These compounds are generally considered to be less harmful and can contribute to the formation of a protective char layer.

Nitrogen-based Flame Retardants:
Nitrogen-containing flame retardants may produce non-flammable gases such as ammonia (NH3) and nitrogen (N2), which can act as a gaseous diluent to reduce the concentration of oxygen and flammable gases.

Boron-based Flame Retardants:
Boron compounds can form a glassy protective layer that acts as a barrier to heat and oxygen. The decomposition of borates can also lead to the production of boric oxide (B2O3), which can contribute to the char formation.

It's important to note that the specific byproducts can vary depending on the exact chemical composition of the flame retardant, the presence of other additives or polymers, and the combustion conditions. Additionally, while some flame retardants are being phased out due to environmental or health concerns, there is ongoing research into developing safer and more effective alternatives.