Alumina Trihydrate ATH

ATH is a relatively inexpensive flame retardant and flller used by the rubber industry. ATH possesses bound water, which is released at higher temperatures to promote a degree of flame retardancy. It can release as much as 34% of its weight as water at elevated temperatures. To be effective, ATH must be used at signiflcantly high concentrations in a rubber compound. ATH grades used in rubber must have sufficiently fine particle size, so as not to degrade the cured physical properties of the rubber compounds. 

Hydrated alumina Hydrated aluminum oxide Al Oj-SHjO A1(0H)3 

There is no formal classification however, precipitated grades are more effective than ground grades. 

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ATH is used as a relatively inexpensive flame retardant. To be effective, it must be used at high concentrations in a rubber compound. However, if the concentration of this ATH fliier is too high, cured compound physicai properties wiii diminish. 

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In other halogen-containing systems, such as flexible PVC and polyolefins, it is preferable to use the zinc borate in conjunction with antimony oxide for maximum performance. In flexible PVC, for example, the zinc borate alone is not very effective in the Oxygen Index test (Fig. 6), but a combination of the zinc borate and antimony oxide (1 1 ratio) outperforms equal weight of antimony oxide at a total loading of more than 10 phr (4). In the presence of alumina trihydrate (ATH), the beneficial effect of using a combination of the zinc borate and antimony oxide is dramatically increased (Fig. 7). 

Fig. 12. Scanning electron micrographs (6000 x) of residues of air-pyrolyses of halogen-free ethylene-vinyl acetate, containing Zinc Borate (33%) and alumina trihydrate (ATH) (33%). At 500°C (top picture), a powdery residue was obtained no sintering took place between the Zinc Borate (small particles) and ATH (large particles). At 550°C (bottom picture), a hard and porous residue was obtained Zinc Borate acted as a sintering agent. A hard and porous residue is a good thermal barrier.

Aluminate cement, 2 415-416 Aluminate ions, silica sols and, 22 394s Aluminates, 2 273-279 analysis, 2 275-276 chemical reactions, 2 273-274 dispersants, 8 710t economic aspects, 2 275 health and safety factors, 2 276 manufacture, 2 274-275 physical properties of, 2 273-274 uses of, 2 276-277 Alumina trihydrate (ATH), 2 274 in synthetic fillers, 11 314-315 Alumina whisker reinforcement, 5 574t Alumina xerogels, X-ray diffraction of, 23 78... 

Fuel, oxygen, and high temperature are essential for the combustion process. Thus, polyfluorocarbons, phosphazenes, and some composites are flame-resistant because they are not good fuels. Fillers such as alumina trihydrate (ATH) release water when heated and hence reduce the temperature of the combustion process. Compounds such as sodium carbonate, which releases carbon dioxide when heated, shield the reactants from oxygen. Char, formed in some combustion processes, also shields the reactants from a ready source of oxygen and retards the outward diffusion of volatile combustible products. Aromatic polymers, such as PS, tend to char and some phosphorus and boron compounds catalyze char formation aiding in controlling the combustion process. 

Translucent plastics may be produced by the addition of fillers such as alumina trihydrate (ATH) which have n values similar to that of the polymer. Such fillers also serve as flatting agents in paints. 

Over 1 million tons each of calcium carbonate and carbon black and over ISO thousand tons of alumina trihydrate (ATH) are used annually as fillers by the U.S. polymer industry. Asbestos continues to be used in moderate amounts (250 thousand tons annually), but it is being displaced by other fillers because of its toxicity. 

Since hdpe is a linear hydrocarbon polymer and, like linear alkanes, sputters when ignited, it burns readily unless admixed with alumina trihydrate (ATH) or other flame retardants. It has a solubility parameter of 7.9 H and low water absorption (0.01%). 

The combustion tendency of polymers in air may be reduced by the incorporation of flame retardants, such as alumina trihydrate (ATH), which releases steam when heated, or chlorinated organic compounds and antimony oxide, which produce antimony chlorides when heated together. 

Unlike the polyurethanes and other previously discussed mortars, polyester cements are produced by a free radical chain copolymerization of a liquid unsaturated polyester and styrene. While most polyester composites are reinforced by fiber glass, polyester mortars are usually filled with silica, clay or alumina trihydrate (ATH). 

The effects of an organoclay and alumina trihydrate (ATH) and/or magnesium dihydroxide (MDH) on the fire retardancy of a ethylene-vinyl acetate (EVA) and low-density polyethylene (LDPE) blend were assessed by TGA and the cone calorimeter (Zhang et al. 2009). 

Dimethyi Methyiphosphonate (DMMP) [756-79-6]. This is a water-soluble liquid, bp 185°C, with the formula CH3P(=0)(0CH3)2, contains 25% phosphorus, which is near the maximum possible for a phosphorus ester, and therefore highly efficient as a flame retardant. It is sold by Akzo Nobel as FYROL DMMR Applications include use as a viscosity depressant and flame retardant in alumina trihydrate (ATH)-filled polyester resins (66) such as used for bathtubs and shower stalls. Some applications have been found in rigid polyurethane foams and as an intermediate for making other flame retardants. In Europe, DMMP has an R46 (mutagen) classification, which deters its use. 

Fillers are inorganic particulates used in the polymeric matrix, both to reduce the final product cost and to improve material processing and certain properties of the pultruded part. Among the most currently used fillers are calcium carbonate, aluminium silicate (cauline), alumina trihydrate (ATH) and calcium sulphate. 

These fillers are of great industrial importance, and are the main subject of this chapter. They owe their fire retardant effectiveness to their ability to decompose endothermically at polymer pyrolysis temperatures, with the release of inert gases such as water. Thus, unlike some other flame retardants, they are able to combine a high level of flame retardancy, with low smoke and low toxic and corrosive gas emissions, and are thus becoming of increasing importance. One of the simplest such materials is aluminium hydroxide (also known as alumina trihydrate, ATH). 

Alumina trihydrate (ATH), also known as hydrated alumina, has the chemical formula A1(0H)3. It is unique among low-cost fillers and extenders for plastics because of its high proportion (34.6%) of chemically bound water. This water of hydration is stable and unreacti ve at the processing temperature of many plastics. When heated to approximately 220 C or higher by exposure to a flame front, the hydrate decomposes into its constituents, with the absorption of a considerable amount of heat [123] ... 

In this chapter we review the effects of hydrated and anhydrous alumina as filler on FR properties of polymer nanocomposites. Nanocomposites are particle-filled polymers for which at least one dimension of the dispersed particles is in the nanometer range. In the following sections, the mechanism and mode of action of nanometric alumina trihydrate (ATH), alumina monohydrate (AlOOH), and alumina (AI2O3) will be discussed. 

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