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Brominated flame retardant
Brominated flame retardants are produced synthetically in 70 variants with very varying chemical properties. There are several groups:
Additional recommended knowledge
Brominated flame retardants (BFRs) replaced PCB as the major chemical flame retardant in 1978 and are an effective flame-retardant. They are applied to prevent electronics, clothes and furniture from taking fire. Some brominated flame-retardants are considered Persistent Organic Pollutants known to bioaccumulate and their consequences are not well-known. Environmental consequences of the PBDEs can be found at the PBDE page.
Brominated flame retardants is the designated name for a group of brominated organic substances that have an inhibitory effect on the ignition of combustible organic materials. BFRs are commonly used in electronic products as a means of reducing the flammability of the product. Bromine based flame retardants are applied to 2.5 million tons of polymers annually, with the annual consumption of PBDEs alone being in excess of 40,000 metric tons. North American industry used about 34,000 metric tons of PBDEs in 1999, making it the largest user of these additives globally; however, a significant proportion of the flame-retarded products manufactured in North America is destined for international markets. The electronics industry accounts for the greatest consumption of BFRs. In computers, BFRs are used in four main applications: in printed circuit boards, in components such as connectors, in plastic covers, and in cables. BFRs are also used in a multitude of products, including, but not exclusively, plastic covers of television sets, carpets, paints, upholstery, and domestic kitchen appliances. BFRs have such a widespread number of applications because they are incredibly effective at fire prevention. In addition to reducing the likelihood that an item will ignite, brominated flame retardants hinder the spread of the fire, and provide valuable extra time in the early stages of a fire when it is much easier to escape. A room fire can very quickly escalate to the point where enough heat is generated that all combustible material in the room bursts into flames. This situation is known as flashover and can occur in a matter of minutes from ignition. Brominated flame retardants slow down the initial burn rate and thereby can help increase the time to flashover, giving the occupants more time to escape.
Hexabromocyclododecane (HBCD or HBCDD) is a ring consisting of twelve carbon atoms with six bromine atoms tied to the ring. The commercially used HBCD is in fact a mixuture of different isomers. HBCD is very poisonous to water-living organisms and can cause harmful long-term effects in water environments. Studies carried out on a HBCD product that is no longer manufactured indicate that Humans can develop allergy at skin contact. This is not the case with current HBCD.
Tetrabromobisphenol A (TBBPA or TBBP-A) is regarded very poisonous to water-living organisms and very persistent. This flame retardant is mainly used in printed circuit boards. Since TBBPA is chemically bound to the resin of the printed circuit board, it cannot get into the aquatic environment from there and therefore poses no actual risk. However, there is also a use of TBBPA in acrylonitrile butadiene styrene, where it is an additive. EU risk assessment concluded in 2005 that TBBPA poses no risk to human health.
Contents in plastics
Content of brominated flame retardants in different polymers:
Testing for BFR in plastics
Until recently testing for BFR has been cumbersome. Cycle time, cost and level of expertise required for the test engineer has precluded the implementation of any screening of plastic component in a manufacturing or in a product qualification/validation environment.
Recently, with the introduction of a new analytical instrument IA-Mass, screening of plastic material alongside manufacturing line becomes possible. A 5 min. detection cycle and a 20 min. quantification cycle is available to test and to qualify plastic parts as they reach the assembly line.
|This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Brominated_flame_retardant". A list of authors is available in Wikipedia.|