Flame retardants are a class of additives that prevent plastics from igniting or inhibiting flame propagation. They are often used in modified industries to improve the flame retardancy of plastics.
According to its use can be divided into two types of additive and reactive type, additive type flame retardant is incorporated in the plastic processing of plastics, mostly used in thermoplastics. Reactive flame retardants are chemically bonded to the polymer chains as monomers during polymer synthesis, are mostly used in thermosetting plastics, and some reactive flame retardants are also useful as additive flame retardants.
In accordance with the chemical structure, flame retardants can be divided into inorganic and organic two types, these compounds contain more halogen and phosphorus, and some contain antimony, boron, aluminum and other elements. Today, we focus on the flame retardant flame retardant effect
Flame retardant flame retardant is the polymer material in the combustion process can prevent or inhibit the speed of its physical or chemical changes, specifically, these effects are reflected in the following aspects.
1 endothermic effect
For example, borax has 10 molecules of crystal water, which takes 141.8 kJ / mol of heat as the water of crystallization is released, and as a result of its heat absorption, the temperature of the material is increased Inhibition, resulting in flame retardant effect. The fire-retardant effect of hydrated alumina is also due to its endothermic effect due to heat dehydration. In addition, some thermoplastic polymer cracking often generated droplets, because they can leave the combustion zone to remove heat of reaction, but also can play a certain flame retardant effect.
2 coverage effect
Its role is to generate a stable coating at a higher temperature, or decomposition of foam-like material, covering the surface of the polymer material, the heat generated by the combustion is difficult to pass into the material, the polymer material due to thermal decomposition The resulting flammable gas is difficult to escape, and play a role in isolating the air from the material, thus inhibiting the material cracking, to achieve the effect of flame retardant. Such as phosphate esters and fire-retardant foam coating can play a role in this mechanism.
3 dilution effect
Such materials can generate a large amount of non-flammable gas when heated and decomposed, so that the flammable gas generated from the polymer material and the oxygen in the air are diluted to reach the flammable concentration range, thereby preventing the flaming combustion of the polymer material . Can be used as a diluent gas CO2, NH3, HCl and H2O and so on. Phosphoric acid amine, amine chloride, amine carbonate, etc. can produce such a non-flammable gas heating.
Brominated polystyrene has excellent thermal stability and excellent fluidity. Its high flame retardancy, thermal stability and light stability and good electrical properties such as mechanical and chemical properties, it has good compatibility with engineering plastics, no precipitation, no migration, no frost, antistatic ability Etc.