Studies of chemical behavior in the different regions of flame retarded polymer flames

摘要

Polymer combution is a complex phenomenon involving condensed phase pyrolysis reactions to evolve flammable species,the 'fuel' in any conflagration.This 'fuel' mixes with entrained air and ignites to produce the flame which both feeds heat back to the polymer surface,thus sustaining the 'fuel' supply,and also releases smode and various combustion products,some of which will be toxic.Flame retardants act by breaking this self-sustaining combustion cycle by a variety of ways.For example,gas phase halogenated retardants remove the highly reactive flame propagation radicals,H,OH,O,thus terminating the combustion chain reaction and extinguishing the flame.Condensed phase retardants act by enhancing the formmation of char rather than volatile 'fuel' during polymer pyrolysis.Intumescent systems take this process further by forming a protective 'foaming char barrier' at a polymer surface exposed to heat.