Flame retardant
Some polymers are inherently flame retardant. Other polymers - including nylons, polyesters, polypropylenes and many other useful and cost-effective materials - are not. They must be modified to achieve the proper level of fire resistance through the use of flame retardant additives.
Mechanisms for flame retardance in plastics
Vapor Phase Inhibition:
During combustion, flame retardant additives react with the burning polymer in the vapor phase disrupting, at a molecular level, the production of free radicals and shuts down the combustion process. This mechanism is commonly used with halogenated flame retardant systems.
Solid Phase Char-Formation:
Char-forming flame retardant additives react to form a carbonaceous layer on the material’s surface. This layer insulates the polymer, slowing pyrolysis, and creates a barrier that hinders the release of additional gases to fuel combustion. This method is commonly deployed by non-halogen systems using phosphorous and nitrogen chemistries.
Quench & Cool:
Hydrated minerals make up a class of halogen-free flame retardant systems commonly used for extruded applications like wire and cable. These systems use an endothermic reaction in the presence of fire to release water molecules that cool the polymer and dilute the combustion process.