Fire Retardants in Plastics

The flame characteristics of a plastic and a measure of its density can often be used to identify the polymer. Polymers can conveniently be identified by a quick test of IQ infrared absorption spectra. A short list of tests of a few plastics is given in Table 11.12. In general, aromatic substances bum with smoky flames. Chloride can be tested with the plastic-coated copper wire which shows a green color in the colorless part of a Bunsen flame. 

The growth of the polymers and plastics industries has meant that a major fraction of the workforce in developed countries is either directly or indirectly employed by plastic-related jobs. As more stable and less costly plastics are developed, more applications are found and growth continues. Because polymers and plastics are based on petroleum and since petroleum is a limited resoiffce, it is essential that continued efforts be made to recycle our plastic wastes—something that is slowly being realized. 

Polymer Density (g/cm ) Type Odor Color Character 

2 TP Benzene Smoky Neutral vapors, difficult to ignite, SE 

28 TS Phenol Yellow smoky Basic fumes, SE, difficult to ignite 

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An application of fire retardants in plastics solves the problem of plastics flammability efficiently but usually creates problems with plastics processing and with plastics properties. In this paper we intend to evaluate various solutions to these problems. 

A new study by three environmental chemists in Canada is the first to measure the levels of polybrominated diphenyl ethers (PBDEs) in the environment. PBDEs are commonly used as fire retardants in plastics, and have been found by the researchers to be accumulating rapidly in animals in the Arctic. Details of the study and its unhappy findings are presented here. 

Uses. Constituent of alloys with other metals (tin, lead, copper) sulfides used in compounding of rubber and manufacture of pyrotechnics trioxide used as a fire retardant in plastics, rubbers, textiles, and paints chlorides used as coloring agents and as catalysts fluorides used in organic synthesis and pottery manufacmre... 

Compounds of antimony are used as fire retardants in plastics and paper, and for veterinary purposes. The metal is found in specialised alloys such as white metal bearings and pewter, which is an alloy of tin, antimony (up to 7.5%) and copper. Concentrations in food are low, generally in the range <0.01 to 0.08 mg/kg, but have been found to be higher in samples of aspic jelly and cream of tartar.40 The... 

Uses Mirex is used in North America and in the southeastern United States for the control of fire and ants. Mirex is also effective against the hamster ant, the yellow-jacket, the Texas leaf-cutting ant, and the Hawaiian mealy bug. A ban on the use of mirex for pest control with exemptions was brought in on June 30, 1978. It has its use as a fire retardant in plastics, rubber, paint, paper, and electrical goods from 1959 to 1972 due to its high melting point and high chemical stability.14,48... 

Vinyl bromide is used as a fire retardant in plastics. 

KK Shen, DJ Ferm. Borate fire retardants in plastics. Paper presented at Twentieth Int Conf on Fire Safety, San Francisco, California, January 12, 1995. 

Trimethyl phosphate (TMP) has widespread industrial uses as a fire retardant in plastics production, thus TMP-based electrolytes might be expected to exhibit good performance with no risk of flame. Wang et al. [40] introduced the mechanism underlying flame retardation as follows ... 

The purpose of this paper is to briefly review recent research into the effectiveness and mode of action of tin compounds as fire retardants in a number of halogenated and halogen-free, plastic and elastomeric substrates. 

Polyester resins. The fire-performance characteristics of unsaturated polyester resins are of utmost importance in many application areas, particularly in the construction, transportation and electronics industries ( 1 3). Consequently, these plastics represent one of the major growth areas for fire retardants in recent years ( 1 4). 

The PBDEs (decaBDE, octaBDE, and pentaBDE) and are used as flame retardants in plastics, electronic equipment, printed circuit boards, vehicles, furniture, textiles, carpets, and building materials. Global demand has increased rapidly since the 1970s with 70,000 tonnes produced in 2001. Their flame retardant activity relies on decomposition at high temperatures, leading to the release of bromine atoms. This slows the chemical reactions that drive 02-dependent fires. HBCDs are a flame retardant added to extruded and expanded polystyrene that is used as thermal insulation in buildings. 

Uses Plasticizer in lacquers, varnishes, polyvinyl chloride, polystyrene, nitrocellulose waterproofing agent hydraulic fluid and heat exchange medium fire retardant for plastics solvent mixtures synthetic lubricant gasoline additive to prevent pre-ignition. 

Bromine occurs in nature as bromide in many natural brine wells and salt deposits. It also is found in seawater at a concentration of 85 mg/L. The element was discovered by A. J. Balard and C. Lowig, independently in 1826. Bromine is used in bleaching fibers and as a disinfectant for water purification. Other appbcations are in organic synthesis as an oxidizing or brominat-ing agent in the manufacture of ethylene dibromide, methyl bromide and other bromo compounds for dyes and pharmaceutical uses as a fire retardant for plastics and in chemical analysis. Ethylene dibromide is used in anti-... 

Some of tlie salts of bismuth are used in medicines for the relief of digestive disorders because of the smooth, protective coating the compounds impart to imtated mucous membranes. Like barium, bismuth also is used as an aid in x-ray diagnostic procedures because of its opacity to x-rays. At one time, certain bismuth compounds were used in the treatment of syphilis. Bismuth oxychloride, which is pcarlcsccnt, has found use in cosmetics, imparting a frosty appearance to nail polish, eye shadow, and lipstick, but may be subject to increasing controls. Bismuth phosphomolybdate has been used as a catalyst in the production of acrylonitrile for use in synthetic fibers and paints. Bismuth oxide and subcarbonate are used as fire retardants for plastics. 

Mirex was first synthesized in 1946 but it was not introduced as a pesticide against hymenopterous insects, especially ants, until 1959 (Smith, 1991). Technical grade mirex consists of approximately 95% mirex and less than 2.5% chlordecone, mostly kepone (Eisler, 1985). Mirex is a stomach insecticide with little contact activity. The main use of mirex was against the imported fire ants in the south-eastern United States (WHO, 1984b). It has also been used to control leaf cutters in South America, harvester termites in South Africa, Western harvester ants in the United States, the pineapple mealy bug in Hawaii and it was proposed to have been used against yellow jacket wasps in the United States (WHO, 1995). Under the trade name of Dechlorane, mirex was used as a fire retardant in electronic components, fabrics, rubber, plastics and electrical goods (Eisler, 1985 WHO, 1995). 

Passive fire protection (flame retardants in plastics) is an important societal benefit. 

Hornsby, P.R. and Mthupha, A., Mechanism of fire retardancy in magnesium hydroxide filled polypropylene, Proceedings from Society of Plastics Engineering Annual Technical Conference (ANTEC 93), New Orleans, LA, 1954—1956, May 9-13,1993. 

Hornsby, P.R., Wang, J., Jackson, G., Rothon, R.N., Wilkinson, G., and Cosstick, K., Analysis of fire retardancy in polyamides modified with magnesium hydroxide filler, Proceedings from Society of Plastics Engineers Annual Technical Conference (ANTEC 94), San Francisco, CA, May 1-5, 1994, pp. 2834-2839. 

Boric oxide is reported to be an effective fire retardant in engineering plastics such as polyphenylene ether (PPE)/high impact polystyrene (HIPS), polyetherketone, and polyetherimide.34-35 It is particularly effective when used in conjunction with PTFE or polyvinylidene fluoride. The use of boric oxide in conjunction with red phosphorus was reported to be an effective combination in fiberglass reinforced polyamide 6,6.36... 

Electrical and electronic devices are made utilizing several various types of plastic materials, thus when discarded their waste is difficult to recycle. The plastics employed in housing and other appliances are more or less homogeneous materials (among others PP, PVC, PS, HIPS, ABS, SAN, Nylon 6,6, the pyrolysis liquids of which have been discussed above). However, metals are embedded in printed circuit boards, switches, junctions and insulated wires, moreover these parts contain fire retardants in addition to support and filler materials. Pyrolysis is a suitable way to remove plastics smoothly from embedded metals in electrical and electronic waste (EEW), in addition the thermal decomposition products of the plastics may serve as feedstock or fuel. PVC, PBT, Nylon 6,6, polycarbonate (PC), polyphenylene ether (PPO), epoxy and phenolic resins occur in these metal-containing parts of EEW. 

Bromine compounds are also used as fire retardants. These compounds are about twice as effective as chlorine compounds on a weight basis, so that significantly lower concentrations are needed. However, bromine compounds are higher in cost than chlorinated compounds and are generally less stable under exposure to heat and light (29). Those compounds containing aromatic bromine are significantly more stable to heat and hydrolysis than the aliphatic type. Examples are decabromodiphenyl oxide (DBDPO), tetrabromobisphenol and tetrabromobisphenol A. A pentabromodiphenyl oxide blend is available for urethane foams and polyesters (34). Aliphatic bromine-type additives are used as flame retardants in plastic foams (polyurethane and polystyrene (33). 

The myriad of government mandates has required plastics for most industrial applications to be self-extinguishing and/or fire retardant. The plastics industry has been responsive to these mandates as well as those imposed by in-house standards of many... 

Froitzheim-Kuhlhom, Ann. 589, 157 (1954). Use as fire-retardant for plastics E. V. Couinlock, Jr.. U5. pat. 3,-382,204 (1965 to Hooker). Accumulation in juvenile Atlantic salmon V. Zitko, Chemosphere 9, 73 (1980). Brief review of fire retardent props T. J. Machmer, Life Prop. Protect., Fire Retard. Oient. AssoC.. Semi-Annu. Meet 1977, 156-174. 

OTHER COMMENTS used in water disinfection used in bleaching fibers and silk used in the manufacture of medicinal bromine compounds and manufacture of anti-knock compounds, such as ethylene bromide, for gasoline chemical intermediate for ethyl bromide, methyl bromide, ethylene dibromide, and other bromine compounds intermediate in manufacture of sedatives, anesthetics, antispasmodic agents, refrigerating and dehumidifying agents use as a fire-retardant for plastics. 

Among antimony compounds are antimony hydride (stibine, a gas) which is the most deadly, followed by antimony sulfide (stibinite), which is used in modern times in camouflage paints (because it reflects IR), and the antimony oxide/lead oxide and carbonate mixture Naples yellow, was used as a pigment and paint as well as a flame retardant in plastics (PVC) for their use in car components, in televisions and so on, because it quenches the fire by reacting chemically with burning materials, although it was also accused of causing cot deaths (see Chapter 10). 

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