Different Types of Flame Retardants
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.
Another type of flame retardant sues a thermal shield to protect the unburned portion of the product from the part that is on fire. Thermal shielding uses intumescent additives. Intumescents are chemicals that swell when exposed to heat. Adding an intumescent to a plastic or textile coating will cause that material to turn into carbonized foam when it gets hot. The foam forms a thermal barrier between the burning material and the unburned material. This will significantly slow the progress of a fire and could save part or most of the object.
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.
Talc and calcium carbonate and inexpensive fillers that many plastics manufacturers use as flame-retardants. Their main purpose is to act as filler. They dilute the plastic so that there is less combustible material available. If there is less combustible material available then there will be less heat produced and the combustion reaction will die out due to lack of fuel.
As necessary as flame retardants are and as many lives as they have saved, there are some environmental and health concerns with certain types. Specifically, brominated flame-retardants are under a lot of scrutiny. Some particular compounds have been banned in Europe like polybrominated diphenyl ethers (PDBEs). However, there have been no concrete scientific studies that show the harmful effects of the vast majority of brominated flame-retardants. Furthermore, there is no other flame retardant that works as well as the halogen/antimony combination.
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.
Tags: chemical legislation, chemicals, flame retardant, halogenated compounds, Manufacturing, palstics, plastics additives, Science, textile coatings, textiles
