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Flame Retardants Work in Various Ways
Any product that is exposed to the public needs to be as safe as possible. One way to try to make plastics and textiles safe is to add flame retardant additives to them. Flame-retardants can prevent a material from catching on fire or slow the progress of a fire giving fire professionals time to fight a blaze. There are several different types of flame-retardants. You need to consider what standards you need to meet and the chemical properties of each before you make your selection.
The first type of flame retardants are compounds that break down endothermically when introduced to high temperatures. The chemical reaction that breaks down the flame retardant absorbs the heat and energy from the surrounding material. This cools the material and prevents fire from starting. Examples of compounds that utilize endothermic degradation are magnesium hydroxide, aluminum hydroxide, and many hydrates. These chemicals are not used often because many manufacturing processes for plastics get hotter than the temperature at which they art to break down.
Intumescents are another type of flame retardant. An intumescent additive is one that swells when exposed to heat. If the intumescent additive is in the plastic or textile coating and is exposed to a flame, the plastic or coating turns into a carbonized foam. The foam acts as a thermal barrier between the burning portion of the product and the portion that has not become fuel yet. This method is called thermal shielding. Using intumescents will not prevent fire from catching, but it will significantly slow the progress of a fire.
The degradation of halogenated compounds is the most common type of flame retardant used. When used in synergy with antimony trioxide, halogen compounds are the most widespread flame retardant used today. Heat will cause brominated or chlorinated compounds to degrade and release hydrogen bromide and hydrogen chloride. The hydrogen bromide and chloride react with the hydrogen and hydroxyl radicals that are present in the ensuing flame to create water and bromine and chlorine radicals. The halogen radicals are far less reactive than the hydrogen and hydroxyl radicals are, so the combustion reaction slows down.
Another common type of flame retardant is one that uses the dilution of fuel method. These flame-retardants are just fillers or dilution agents. They dilute the plastic so that there is less combustible material. Talk and calcium carbonate are used most often. With less combustible material present, there will be less heat produced per volume of material and thus slow the combustion reaction.
Flame-retardants save lives every day and are a very important part of many consumer goods. However, there are some health and environmental concerns with some, specifically brominated flame-retardants. Some specific brominated compounds like polybrominated diphenyl ethers (PDBEs) have been banned in Europe. Most brominated compounds have not been subject to bans. There has not been a single study that resulted in banning the vast majority of halogenated flame-retardants. The halogen/antimony combination is still the best option manufacturers have available to them for a flame retardant and as long as there is no alternative that works as well, they will continue to be used.
Most flame retardant products have that feature because some government body mandates it. The flame retardant industry is a regulated one and there are several different standards. When looking for a flame retardant additive, make sure that it meets whatever standard is appropriate for your industry and your country.
About the Author Amspec LTS is a great substitute for the recently discontinued TRUTINT 50. Check out all of the grades of antimony trioxide that Amspec has to offer.
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