Halogenated Flame Retardants
Halogenated FR additive benefits:
Very effective at lowering flammability in a wide range of polymers.
Provide good fire performance even after repeated recycling of polymer + FR resin.
Halogenated FR additive drawbacks:
Always generate more smoke and carbon monoxide during burning.
Can be overwhelmed in high heat flux fires (little to no FR effectiveness).
Under regulatory scrutiny due to perceived environmental problems.
Overall an old technology (since 1930s) but proven to work.