Fire brominated/chlorinated organic

Jansson B, Andersson R, Asplund L, et al. 1993. Chlorinated and brominated persistant organic compounds in biological samples from the environment. Environ Toxicol Chem 12(7) 1163-1174. JaretP. 2000. Health concerns Defense systems under fire. 38(6) 36-41. 

Typically a brominated or chlorinated organic compound is added to the polymer or, in suitable cases, halogenated structures are introduced into the polymer chain by copolymerization to prepare fire-retardant polymer materials. Metal compounds, such as antimony trioxide, which do... 

Effective additives include urea, ammonium phosphate, magnesium carbonate, antimony oxide, alumina hydrate, silicates, and borates. Though brominated and chlorinated organic compounds are fire retardants, they decompose at high temperatures to produce HBr and HCl which, as corrosive gases, can often do more harm than good. 

Organic compounds of bromine usually resemble their chlorine analogues but have higher densities and lower vapor pressures. The bromo compounds are more reactive toward alkaUes and metals brominated solvents should generally be kept from contact with active metals such as aluminum. On the other hand, they present less fire hazard one bromine atom per molecule reduces flammabiUty about as much as two chlorine atoms. 

Of major concern are the health and environmental impacts of the abundant chlorinated and brominated hydrocarbons (ref. 2). These materials have numerous industrial applications as pesticides, solvents, propellants, refrigerants, plastics, fire retardants and extinguishers, disinfectants for drinking water, pharmaceuticals and electronic chemicals. Many chemical manufacturers utilize chlorinated and brominated organics as intermediates. It is estimated, for instance, that almost 85 % of the pharmaceuticals produced in the world require chlorine at some stage of synthesis. 

Second, reaction 8.9 and other relevant reactions appear to occur preferentially on available solid surfaces, which are often ice crystals but may also be particles of sulfate hazes from volcanic eruptions or human activity. Third, volatile bromine compounds are even more effective (via Br atoms) than chlorine sources at destroying ozone methyl bromide is released into the atmosphere naturally by forest fires and the oceans, but anthropogenic sources include the use of organic bromides as soil fumigants (methyl bromide, ethylene dibromide) and bromofluorocarbons as fire extinguishers (halons such as CFsBr, CF2BrCl, and C2F4Br2). 

A possible destruction upon impact of zinc-halogen batteries might lead to the release of chlorine gas or bromine liquid and vapor. A study of the effects of spilling a full load of chlorine hydrate on hot concrete concluded that the probability of lethal accidents appears to be no more serious than that caused by gasoline fires in ICE-powered cars. The bromine vapor pressure above the organic complex is lower than that of chlorine above chlorine hydrate its lethal dose, however, is smaller and the spill cleanup and dispersion problems may be more severe. 

Fire resistant PU are obtained by the addition or by introduction into the PU structure of special compounds, called flame retardants. The flame retardants are organic compounds containing halogens (chlorine, bromine) and phosphorus. Compounds of antimony (Sb) or boron [1-13] are rarely used. Sometimes inorganic compounds are used as flame retardants for PU, such as, hydrated alumina (Al203 nH20), Sb203 or ammonium polyphosphate [1-3, 14]. 

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