Flame-retardant additives magnesium hydroxide

Various types of flame retardant additives have been used in polyamides including magnesium hydroxide - red phosphorus in glass fibre reinforced polyamide [76], chemically modified montmorillonite organoclays [77], surface modified nanosilica [77], carbon nanofibres in polyamides 11 and 12 [78], and dodecyl sulfate anion-modified MgAl (H-DS) interlayers in polyamide 6 [79]. 

Martinswerk of Germany said that its Magnifm flame retardants have been specifically created for applications as flame retardant additives, compared with other magnesium hydroxides that have been manufactured from seawater with the pharmaceutical industry in mind. Magnifin is especially recommended for situations where low smoke emission and a high thermal stability are required from a halogen-free retardant. 

Reduction of flammability and smoke production when submitted to fire - flame retardant additives are used (e.g., antimony trioxide, phosphorus compounds, aluminium trihydroxide, magnesium hydroxide, zinc borates)... 

One application where red phosphorus is widely used is for electrical switches and moimtings moulded from glass-filled nylon. These are internal parts where the brick-red colour imparted by the phosphorus is unimportant. Other flame retardants are also effective in nylon but different end uses favour different additives depending on their performance characteristics. This is shown in Table 1 where red phosphorus is compared with a t)rpical halogen system and two other halogen-free additives, magnesium hydroxide and melamine cyanurate. Among the... 

To improve the fire retardancy of polypropylene, beyond the UL 94 V-2 level, it is necessary to use blends of aromatic bromine fire retardants with antimony trioxide as a synergist. The usual loading is between 35% and 40% fire retardant however, the additional cost may prohibit commercialization. Moreover, the presence of aromatic bromine increases the photooxidation of polypropylene67 69 inactivating hindered amines. To reduce the cost without losing in efficacy the combination of brominated flame-retardant/antimony trioxide system with magnesium hydroxide... 

Metal hydroxides in combination with various silicon-containing compounds have been used to reduce the amount of additive required to achieve a required level of flame retardancy in a variety of polymeric materials, including polyolefins.62-63 Systems that have been used contain a combination of reactive silicone polymers, a linear silicone fluid or gum, and a silicone resin, which is soluble in the fluid, in addition to a metal soap, in particular magnesium stearate. However, there is little insight given into how these formulations work. 

The combination of melamine with hydrated mineral fillers can improve the fire retardancy behavior of PP, eliminating at the same time the afterglow phenomenon associated with these fillers used in isolation.70 Similarly in EVA copolymer, antimony trioxide used in combination with metal hydroxides has been reported to reduce incandescence.56 Chlorinated and brominated flame retardants are sometimes used in combination with metal hydroxides to provide a balance of enhanced fire-retardant efficiency, lower smoke evolution, and lower overall filler levels. For example, in polyolefin wire and cable formulations, magnesium hydroxide in combination with chlorinated additives was reported to show synergism and reduced smoke emission.71... 

Okobo, N., Okumura, H., Okoshi, M., and Hamada, H., Flame retardancy of EVA/Nano magnesium hydroxide hybrid, Proceedings from Additives 2004, Clearwater Beach, FL, March 22-24, 2004. 

Additive flame-retardants may be more easily incorporated in polyurethane formulation. Several class of compounds have been used to improve flame retardancy of PU foams such compounds are halogen- (very often chloroalkyl-phosphate) or phosphorous-based compounds, although also other substances, like as EG, melamine, aluminum trihydrate and magnesium hydroxide, may be used. 

Consideration is given to the influence of combinations of zinc hydroxystannate (ZHS) with hydrated fillers, on the fire properties of plasticised PVC and polychloroprene. It is shown that magnesium and aluminium hydroxides specially coated with ZHS, confer significantly increased combustion resistance and lower levels of smoke evolution to these polymers. This permits large reductions to additive loading relative to unmodified filler, without sacrificing flame retardant or smoke suppressant performance. 10 refs. 

Flame-retardants are used as additives in the preparation of fire retardant paints. They are decomposed by heat to produce nonflammable components, which are able to blanket the flames. Both inorganic and organic types of flame-retardants are available in the market. The most widely used inorganic flame-retardants are aluminum trihydroxide, magnesium hydroxide, boric acid, and their derivatives. These substances have a flame-retardant action mainly because of their endothermic decomposition reaction and their dilution effect. The disadvantage of these solids is that they are effective in very high filler loads (normally above 60 percent). 

Special considerations magnesium hydroxide and basic magnesium carbonate are used as flame and smoke retarding additives ... 

Natural fiber-reinforced polyolefins are commonly apphed to automotive and constmction applications. The most abundantly used additive is fire retardant. Flammability is an important factor that often limits the application of composites to a specified field. Magnesium hydroxide is the most common flame retardant material used in the constmction industry. This filler responds well to surface modifiers and decomposes by an endofliermic reaction that releases water at temperatures close to the polymer degradation temperature as show in Eq. 6.1. Rothon et al. [78] studied the effects of magnesium hydroxide on polypropylene as a flame retarder of 60 % by weight. The smdy found less heat emission at 100 kWm after 6 min of fire exposure compared to filled PP without Mg(OH)2 at 500 kWm. ... 

Specially coated magnesium and aluminium hydroxides confer significantly increased combustion resistance and lower levels of smoke evolution, permitting large reductions in additive loading, without sacrificing flame retardant or smoke suppressant performance. 

Intumescents are said to have a key advantage over filler-type non-halogenated flame retardants in that they are effective at lower addition levels than traditional materials. For example, an intumescent based on ammonium polyphosphate will achieve the same level of protection at addition levels of 25 to 35 parts by weight (pbw) as atypical non-halogenated flame retardant, such as alumina trihydrate or magnesium hydroxide, at between 60 and 70 parts by polymer weight. 

Silicone as an extra ingredient to a magnesium hydroxide and Firebrake ZB flame retarded EVA reduces the peak of heat release rate, for a total loading of 65%. It has been found that the residue for samples with zinc borate and the silicone is multicellular, rigid and hard compared to that with silicone and magnesium hydroxide alone. This shows how combinations of additives can be used to influence the morphology of the degrading residue and subsequently lower the peak rate of heat release. 

Flame retardant performance can be enhanced in some magnesium hydroxide protected systems by the incorporation of clay or talc. In a polyethylene formulation the addition of 60% magnesium hydroxide and 5% tale instead of 65% magnesium hydroxide, improved the V-0 rating from 3.2 mm to the thinner 1.6 mm level. More tale at the expense of further magnesium hydroxide dropped the V-0 rating baek to 3.2 mm. 

Red phosphorus flame-retardants are effective in thermoset resin systems and also elastomers, often combined with ATH, or magnesium hydroxide in elastomers. A wide range of treated red phosphorus in dispersion or concentrate form, offered by Clariant, is easier to handle and safer to transport, compared with powder grades. Such phosphorus additives do not affect the electrical properties of the composite, and they have little impact on the physical properties of the laminates manufactured. 

In the present chapter, we report some of om study on both raw and surface-modified Grewia optiva fiber-reinforced UPE matrix-based composites, which possess enhanced mechanical and physico-chemical properties when compared with UPE matrix. In addition to the effect of flame retardants, i.e., magnesium hydroxide and zinc borate, on flame resistance, the behavior of resulted Grewia optiva fiber-reinforced composites have also been evaluated and was foimd to be improved. A significant discussion on the work of other researcher s work has also been added in the chapter. 

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