In the field of polymer materials, phosphorus flame retardants, as important "fire guards", play a key role in ensuring the fire safety of materials. There are many types of phosphorus flame retardants, including phosphate esters, ammonium polyphosphate, and melamine phosphate.

Its flame retardant mechanism is diverse. In terms of gas phase flame retardancy, thermal decomposition produces phosphorus-containing free radicals, such as PO・, etc. These free radicals can capture highly active free radicals (such as H・, OH・) generated during the combustion process, interrupt the combustion chain reaction, and inhibit the spread of flames. In terms of condensed phase flame retardancy, it can promote the formation of a carbon layer on the surface of the polymer material. The carbon layer is like a barrier for heat and oxygen insulation, preventing heat from transferring to the inside of the material and reducing the generation of combustible gases. For example, ammonium polyphosphate first decomposes at high temperature to produce ammonia and polyphosphoric acid, and polyphosphoric acid further dehydrates to form pyrophosphoric acid with strong dehydration effect, which promotes the dehydration and carbonization of polymers and forms a stable carbon layer structure.

In practical applications, phosphorus-based flame retardants are widely used in polymer materials such as plastics, rubber, and fibers. In plastic products, such as electronic and electrical housings, wire and cable insulation layers, etc., adding phosphorus-based flame retardants can make them reach a higher flame retardant level, such as UL94 V-0 level, effectively reducing the risk of fire. In rubber products, it can be used to make conveyor belts, tires, etc. to improve their fire resistance. In the field of fibers, synthetic fibers such as polyester and nylon can be flame-retarded and used to make firefighting suits, work clothes, etc. to ensure the safety of personnel in fire environments.