4 Additives That Make Plastics Flame Retardant
In order to meet safety regulations, being able to make plastics flame retardant is essential. Otherwise, it’s liable to burn, which doesn’t only present the dangers of a fire but also harmful chemicals that are released into the air. Luckily, there are options for additives that make plastics flame retardant. Keep in mind that this only means that the plastics will not burn. The plastics can still melt, as making them flame retardant doesn’t increase their heat resistance. It only ensures that they will not burn.
How do plastics become flame retardants?
Let’s look at how plastic burns to get a better understanding of how these additives make it flame retardant. Plastics burn in a process called pyrolysis. This means that as the plastic material breaks down due to excessive heat, the polymer chains separate into hydrocarbon molecules and flammable gases. The gas is what burns, leaving behind the melted and charred plastic. Flame retardants keep plastics from burning by stopping the breakdown of the polymer chains so there isn’t gas present that can burn.
Flame retardants stop this from happening in different ways depending on the additive and the type of plastic. There are two kinds of additives, active and reactive. The active additives are blended into plastic polymers, while reactive additives are inserted into the polymer molecule itself.
4 ways to make plastics flame retardant
There are four processes that can be used put additives into plastics and make sure they don’t burn.
- Endothermic Degradation – In this process, mineral compounds like aluminum and magnesium hydroxides are used. When added to the plastic polymers, the minerals are there to take the heat. When exposed to high heat, the mineral compounds will break down endothermically. The result is that the heat is removed from the plastic, cooling the material. This has been a popular way to make plastics flame retardant, but it requires high processing temperatures for plastics and low decomposition temperatures for hydroxides and hydrates.
- Gas-Phase Radical Quenching – Brominated flame retardants (BRFs) are the most common flame retardant plastic additives and are organohalogen compounds. When exposed to heat, they release hydrogen chloride and hydrogen bromide which reach the H and OH radicals in the flame. This produces chlorine and bromine radicals, which are less reactive. They will retard the oxidation reactions within the flame. This process works on many different plastic polymers and is a low-cost option. You need to be careful though, as many of the halogenated retardants have been banned for being toxic to people and animals.
- Thermal Shielding – As the name suggests, phosphorus flame retardants create a barrier around the plastic which shields it from the fire. When heated, phosphorus forms phosphoric acid that chars the solid of the plastic and creates a thick layer of carbon. The charring lessens the pyrolysis by making fuel for the fire less available. You can also purchase halogenated phosphorus compounds that include halogen as well. The halogen will act on the gas phase of the fire while the phosphorus acts on the solid phase, offering another layer of protection.
- Synergists – As mentioned in thermal shielding, many flame retardant additives are used together to increase the protection. Synergists are the safest way to go, as you want as much assurance the plastics are flame retardant as you can get. In gas-phase radical quenching, brominated compounds are used with antimony trioxide. They act together as a catalyst to speed up the release of bromine and chlorine chemicals to inhibit the pyrolysis process.
Plastic Service Centers | Flame retardant additives for plastics
If you want to make sure that your plastic products are safe and flame retardant, then you need a reliable distributor for your flame retardant additives. Plastic Service Centers are a proven distributor who can make sure you have as much of the materials you need as soon as you need them. We have strategically placed our warehouses in the Midwest and throughout the country to guarantee we can ship to you in a timely fashion. We carry over 4 million pounds of materials at any given time, and we can ship anywhere in North America, including the U.S.A, Canada, and Mexico.