Flame retardants for polymers

Some inorganic fillers are used as flame retardants in rubber base formulations. Flame retardants act in two ways (1) limiting or reducing access of oxygen to the combustion zone (2) reacting with free radicals (especially HO ), thus acting as terminator for combustion-propagation reaction. The additives most widely used as flame retardants for polymers are antimony oxides and alumina trihydrate. 

We previously reported that brominated aromatic phosphate esters are highly effective flame retardants for polymers containing oxygen such as polycarbonates and polyesters (9). Data were reported for use of this phosphate ester in polycarbonates, polyesters and blends. In some polymer systems, antimony oxide or sodium antimonate could be deleted. This paper is a continuation of that work and expands into polycarbonate alloys with polybutylene terephthalate (PBT), polyethylene terephthalate (PET) and acrylonitrile-butadiene-styrene (ABS). 

G. Beyer, Short communication Carbon nanotubes as flame retardants for polymers, Fire and Materials, vol. 26, pp. 291-293, 2002. 

Montaudo, G., Scamporrino, E., and Vitalini, D. 1983. Intumescent flame retardants for polymers. II. The polypropylene-ammonium polyphosphate-polyurea system. J. Polym. Sci., Polym. Chem. Ed. 21 3361-3371. 

Beyer, G., Nanocomposites—A new class of flame retardants for polymer and cable applications, Proceedings from Conference on Functional Fillers for Plastics, September 15-17, Intertech, Portland, Maine, U.S.A., Paper 16, 2004. 

Flame retardants for polymers can also be classified as reactive (the flame-retarding agent reacts chemically with the polymer to become an integral part of the molecule) or additive (nonreactive agents that are simply blended or mixed into the compound). Flame retardants can also be classified by their major chemical group, as shown in Table 9.14. 

To summarize, the field of flame retardancy for polymers is in a state of flux, and multiple new technologies and approaches are expected to arise in the coming decade. In this entry, we focus on some new technology from our laboratory, including nonhalogenated flame retardants synthesized from bromi-nated starting materials, and inherently fire-safe and low-flammability polymers. 

Morgan, A.B. Tour, J.M. Synthesis and Use of Non-Halogenated Aromatic Compounds as Flame Retardants for Polymer-Containing Materials. U.S. Patent 6,566,429 B2, 20 May, 2003. 

MAGNESIUM HYDROXIDE AS A FLAME RETARDANT FOR POLYMER APPLICATIONS... 

A particularly attractive application of hydrotropy in organic synthesis arises when the product is bulkier than the reactant, with the result that it has lower solubility than the reactant in the hydrotrope solution. Consequently, it selectively precipitates out of the reaction mixture and can be easily filtered out. Then the hydrotropic solution can be recycled, thus minimizing the environmental hazards associated with waste disposal. An important example is the synthesis of Diels-Alder adducts that act as flame retardants for polymer blends and formulations. One of these is also used in the manufacture of the pesticide Endosulfan. The reaction involves a diene such as hexachloro-pentadiene or anthracene and a dienophile such as p-benzoquinone or maleic anhydride. The following typical reaction carried out by Sadvilkar (1995) gave excellent results ... 

Uses Flame retardant for polymers, textiles, cellulose materials, esp. insulation felts blowing agent for Intumescents... 

Uses Flame retardant for polymers, intumescent paints/coatings, plastics (polyesters, polymethyl methacrylate, polyolefins, PS, PU foams), textiles, paper intumescent paint/mastic ingred. catalyst in intumescent systems... 

Beyer, G. (2002) Nanocomposites a new class of flame retardants for polymers. Plast. Addit Compound., 10, 22-8. Mouritz, A.P. (2003) Fire resistance of aircraft composite laminates. J. Mater. Sci. Lett., 22, 1507-1509. 

Dimelamine phosphate CAS 56974-60-8 Empihcal C6H15N12O4P Properties Wh. powd. sol. 2 g/l in water m.w. 350.24 dens. 1.66 kg/l dec. 300 C Uses Flame retardant for polymers, intumescent paints/coatings, plastics (polyesters, polymethyl methacrylate, polyolefins, PS, PU foams), textiles, paper intumescent paint/mastic ingred. catalyst in intumescent systems Manuf/Distrib. DSM Chem. N. Am. http //www. dsmna. com Trade Name Synonyms Amgard ND t[Rhodia/Phosphorus Perf. Derivs. 

Uses Flame retardant for polymers, plastics, PP, PE, PVAc, thermosets (poiyester, epoxies) deodorant for air purification cement... 

Uses Reactive flame retardant for polymers which undergo crosslinking, e.g., XLPE and EPDM also rec. for ABS, and other styrenics Manuf/Distrib. AmeriBrom http //www. ameribrom. com Trade Name Synonyms Actimer FR-1033 t[AmeriBrom http //www.ameribrom.com-. Dead Sea Bromine http //www.dsbg.com]-, FR-1033 [AmeriBrom http //www.ameribrom.com. Dead Sea Bromine http //www.dsbg.com]... 

Synonyms 2-Chloro-1-propanol phosphate (3 1) 1-Propanol, 2-chloro-, phosphate (3 1) TMCP Tris (P-chloropropyl) phosphate Empirical C19H18CI3O4P Properties M.w. 447.69 Toxicology TSCA listed Uses Flame retardant for polymers Manuf./Distrib. Aceto http //www.aceto.com Trade Name Synonyms Amgard TMCP T[Rhodia/Phosphorus Perf. Derivs. http //www.rhodia-ppd.com]] Antiblaze 80 [Rhodia/Phosphorus Perf. Derivs. http //www.rhodia-ppd.com]... 

Beyer, G. 2002. Nanocomposites A new class of flame retardants for polymers. Plastic Additives and Compounding A.22-27. 

Horold, S. Phosphinates, the flame retardants for polymers in electronics, http //www.flameretardants-online.com/news /downloads / over enghsh / phosphinate.pdf. 

Figure 1. Schematic of reaction pathways to the production of polybrominated dibenzofurans and polybrominated dibenzodioxins from polybrominated diphenylethers (a common family of flame retardants for polymers). Note x+y can equal 5, 8, or 10 implying penta-, octa- or deca-substitu-tion.

Tetrachlorobisphenol-A 2,2, 6,6 -Tetrabromobisphenol-A Figure 7.19 Halogenated BPA used as flame retardants for polymers. 

A number of studies describe red phosphorus as a flame retardant for polymer materials. Amorphous red phosphorus, P4, melts at 460°C. Above 416 C it is able to sublime (sublimation heat 19.7 kcaiymole) [84], During sublimation, unlike the vapors of the white modification which consist of P4 molecules, red phosphorus evaporates in the form of Pj molecules [85]. At high temperatures, a conversion of the white modification into the red modification is observed. 

The LDH materials can be very interesting to industry as they combine the features of conventional metal hydroxide-type fillers, like magnesium hydroxide (MH), with the layered silicate type of nanofillers, Hke montmorillonite. The major area of interest in this regard is the role of LDH materials as potential non-halogenated, non-toxic flame retardant for polymer matrices. For years, scientists have been using the concept of nanotechnology to improve the flame retardancy of polymer nanocomposites. This approach involves the dispersion of inorganic filler, in nanoscale, as flame retardants into a polymer matrix. Usually, for this purpose, layered silicates and various other nanoparticles (MgO, MH, etc.) are used after suitable pretreatment. Several research reports have already shown that such an approach indeed improves the flame retardancy of the composites [22,23]. 

An excellent review of the work on the flame retardancy of polymer nanocomposites was published in 2007 [3]. This chapter will focus on the evaluation of the proposed mechanisms for enhanced thermal stability of polymer-clay nanocomposites, the proposed relationships between enhanced thermal stability of polymer-clay nanocomposites and flame retardancy, and the synergies that develop between traditional flame retardants for polymers and polymer-clay nanocomposites. 

Evaluations of potential synergies between traditional flame retardants for polymers and polymer-clay nanocomposites... 

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