1. Provide a layer of oxygen-insulated coating. For example, the bromide produced during combustion of bromine flame retardants is an oxygen-insulating coating.




2. Formation of free radicals which can react with plastics and play a flame retardant role. Their combustion performance with the reaction products of plastics is very poor.



3. Produce a gas that can smother the flame. For example, antimony trioxide, when it meets HCL emitted by combustion in PVC, it reacts to produce a stuffy gas, i.e. antimony nitrogen oxide.



4. Absorbing the heat generated during combustion plays the role of cooling and slowing down the combustion rate. For example, aluminium hydroxide, whose molecule contains 34% of the chemically associated water, remains stable at most plastic processing temperatures, but begins to decompose at temperatures above 200 degrees Celsius, releasing water vapor. And for every molecule of aluminium hydroxide decomposed, it absorbs 36 kilocalories of heat.