Flame Retardant Definition & Classification
Flame Retardant Definition
Combustion could occur when a substance is heated to its flammable temperature in the presence of oxygen. Flame retardants are generally designed to provide a particular level of resistance to ignition or flame spread. This is achieved by suppressing oxygen availability, building up of char at the surface, inhibiting the combustion reaction within the flame area, or by other mechanisms .
Flame Retardant Classification
Flame retardant can be classified by different methods：
By whether it contains halogens;
Flame retardant can be classified into
Halogen Flame Retardant
Halogen flame retardant works in a gas
By Organic and Inorganic Types;
Flame retardant can also be
Inorganic Flame Retardants
Inorganic flame retardants include aluminum trioxide Al(OH) 3, magnesium hydroxide Mg(OH) 2, Antimony trioxide(sb2o3), ammonium polyphosphate, and red phosphorus, boric acid. This group represents about 50% by volume of the global flame retardant production. The remaining categories are organic FRs.
Inorganic FRs do not evaporate by eﬀect of the combustion heat but decompose in
The endothermic decomposition of aluminum hydroxide primarily leads to the cooling of polymer and the formation of a protective layer of aluminum oxide. Moreover, the formation of water
By chemical category:
By chemical category, FRs can be classified into categories are as the table below:
• Halogenated additives in which brominated FRs are most widely used, halogenatedFRs work in the gas phase above the burning polymer surface by chemically interrupting the flame propagation mechanism.
• Intumescent additives include phosphorus FRs that react with the polymer substrate to produce a char layer which forms an effective barrier between heat source and oxygen and the fuel derived from pyrolysis of the polymer. The efficiency with which a polymer can be flame retarded is related to its inherent tendency to char.
• Spumific additives include inorganic FRs which decompose at the combustion temperature of the polymer to produce inert gases, such as CO2 andH2O, which dilute the combustion gases and hinder burning.
By either reactive or additive.
Reactive flame retardants which used mainly in thermosets(epoxy resin, UP, polyurethane) are chemically bound to the polymer; Additive FRs which used primarily in thermoplastics(ABS, PC/ABS, HIPS, EPS, PP, PE, PA, PC, PBT) are physically mixed with the resin during or after
Trend of Flame Retardant
Flame retardants can reduce processability and interfere with other additives. The ideal FR additive is colorless, easily blended, compatible with the substrate (no blooming and plate-out), has no deleterious effects on (mechanical)properties of the substrate, allows all finished article