Fire-retardant materials

High purity hexafluorozirconic acid and its salts are produced by Advance Research Chemicals of the United States, and Akita and Moritta of Japan. The technical-grade green-colored material is suppHed by Cabot Corp. of the United States. In 1993, the U.S. market for fluorozirconic acid was about 250,000 kg/yr the world market was less than 500,000 kg/yr. A principal part of this production is consumed by the wool, garment, and upholstery industries. The 1993 price varied between 2.4 to 6.6/kg depending on the quaUty and quantity required. Potassium fluorozirconate [16923-95-8], K ZrF, is commercially important the world market is about 750,000 kg/yr. The most important appHcation is as a fire-retardant material in the wool (qv) industry, for the manufacture of garments, upholstery for aeroplane industry, and children s clothes (see Flame retardants). The 1993 unit price was between 5.0 and 6.6/kg. 

At present there is no small-scale test for predicting whether or how fast a fire will spread on a wall made of flammable or semiflammable (fire-retardant) material. The principal elements of the problem include pyrolysis of solids char-layer buildup buoyant, convective, tmbulent-boundary-layer heat transfer soot formation in the flame radiative emission from the sooty flame and the transient natme of the process (char buildup, fuel burnout, preheating of areas not yet ignited). Efforts are needed to develop computer models for these effects and to develop appropriate small-scale tests. 

The first phenomenon observed is the improved resistance of these materials to combustion, in a way that they may be classified as intrinsically self-extinguishing substrates. For instance, the LOI value for PTFEP is reported to be 48 [452], which is much higher than reported for classical organic plastics [283], while phosphazene fluoroelastomers have been considered as fire-retardant materials since the very beginning of their preparation and utilization [562]. Similarly to aryloxy- and arylamino- substituted POPs [389,390] (vide infra),it may be expected that the flame-resistance properties of phosphazene fluoroelastomers could be successively exported to stabihze organic macromolecules when blended with these materials. 

The use of copolymers is essentially a new concept free from low-MW additives. However, a random copolymer, which includes additive functions in the chain, usually results in a relatively costly solution yet industrial examples have been reported (Borealis, Union Carbide). Locking a flame-retardant function into the polymer backbone prevents migration. Organophosphorous functionalities have been incorporated in polyamide backbones to modify thermal behaviour [56]. The materials have potential for use as fire-retardant materials and as high-MW fire-retardant additives for commercially available polymers. The current drive for incorporation of FR functionality within a given polymer, either by blending or copolymerisation, reduces the risk of evolution of toxic species within the smoke of burning materials [57]. Also, a UVA moiety has been introduced in the polymer backbone as one of the co-monomers (e.g. 2,4-dihydroxybenzophenone-formaldehyde resin, DHBF). 

A.R. Horrocks and D. Price (eds), Fire Retardant Materials, Woodhead Publishers, Cambridge (2001). 

When samples are exposed vertically to a flame or another heat source, some materials melt and drip, and do not burn up completely. This will cause their smoke results to be artificially low [9]. Burning samples horizontally makes material performance comparisons in a small scale test more logical because the entire sample will be burnt in every case. This is very relevant when dealing with fire retarded materials which do not melt or drip, and will thus, yield similar smoke production results in the vertical and horizontal modes. 

Many useful products, such as superglue and fire-retardant materials, are domestic spin-offs from research that is related to military applications. Military expense budgets are large, in part, because of the money required to support this research. In your opinion, should military budgets be exempt from cost-conservation measures that governments typically must consider Debate this question with your classmates, and issue a statement that summarizes your decisions. 

Asbestos is a naturally occurring mineral and was widely used as an insulation material in building constmction [35]. Asbestos possesses a number of good physical characteristics that make it useful as thermal insulation and fire-retardant material. It is electrically nonconductive. 

Suitable fire retardant materials include halogen compounds in combination with antimony compounds, including, tetrabromobis-phenol A and antimony trioxide. Examples for halogen free flame retardants are phosphate esters, such as Hoechst Celanese AP422 or Hoechst Celanese IFR 23. 

T.R. Hull, Challenges in fire testing Reaction to fire tests and assessment of fire toxicity. In Advances in Fire Retardant Materials, D. Price and A.R. Horrocks (eds.) Woodhead Publishing Ltd., Cambridge, U.K., 2008, Chap. 11, pp. 255-290. 

Castrovinci, A. Lavaselli, M. Camino, G. Recycling and disposal of flame retarded materials. In Advances in Fire Retardant Materials. Horrocks, A. R. Price, D., Eds.., Boca Raton, FL CRC, 2008, pp. 213-232. 

Fire Retardant Materials, Honocks, A. R. and Price, D. (Eds.), 2000, Woodhead Publishing Limited,... 

Kozlowski, R. and Wladyka-Przybylak, M. 2001. In Fire Retardant Materials, Woodhead Publishing Limited, Cambridge, England, pp. 531-574. 

Fire-retarded materials functioning in the condensed phase, such as intumescent systems, form, on heating, foamed cellular charred layers on the surface, which protects the underlying material from the action of the heat flux or the flame. It is recognized that the formation of the effective char occurs via a... 

Lewin M, Weil ED. Mechanisms and modes of action in flame retardancy of polymers. In Fire Retardant Materials. Horrocks AR, Price D, Eds. Woodhead Publishing Limited Cambridge, U.K., 2001 chap. 2, pp. 31-68. 

Schartel B, Hull TR. Development of fire retarded materials—interpretation of cone calorimeter data. Fire Mater. 2007 31 327-354. 

B. Schartel and T.R. Hull, Development of fire-retarded materials Interpretation of cone calorimeter... 

P. R. Dickinson, "Evolving Fire Retardant Materials Issues A Cable Manufacturers Perspective," Fire Technol. (Nov. 1992). 

ASTM E 84 Steiner Tunnel Test. This test, which uses very large samples (20 ft x 20 1/4 in.) is referenced in all model building codes for evaluating flame spread and smoke emission of foam plastic insulation. The test apparatus consists of a chamber or tunnel 25 ft. long and 17 3/4 X 17 5/8 in. in cross section, one end of which contains two gas burners. The test specimen is exposed to the gas flame for ten minutes, while the maximum extent of the flame spread and the temperature down the tunnel are observed through windows. Smoke evolution can also be measured by use of a photoelectric cell. The flame spread and smoke evolution are reported in an arbitrary scale for which asbestos and red oak have values of 0 and 100, respectively. More highly fire-retardant materials have ratings of 0-25 by this method. 

Other minor components may be included to impart specific properties, for example the addition of wax to improve short term response to wetting is almost universal. Insecticide and fungicides to impart resistance to fungal or insect attack may be added, while fire retardant materials can be incorporated to give panels with a specified fire performance. 

The concept of fire-retardancy is remarkably old. The Greek historian, Herodotus, in 484-431 BC recorded that the Egyptians imparted fire-resistance to wood by soaking it in a solution of alum (potassium aluminum sulfate) [Browne, 1958]. The Romans added vinegar to the alum for the same purpose. Vitruvius in the first century BC described the natural fire-retardant properties of the larch tree and some military applications of fire retardant materials such as plaster of clay reinforced with hair [Vitruvius, I960]. In 1638, Circa recorded that Italian theaters were painted with a mixture of clay and gypsum (potassium aluminum silicate and hydrated calcium sulfate) to protect them from fire. Wild was issued a British patent in 1735 for his process of treating wood with a mixture of alum, ferrous sulfate and borax (sodium tetraborate decahydrate). And Gay-Lussac in 1821 showed that a solution of ammonium phosphate, ammonium chloride and borax acts as a fire-retardant for wood. 

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