José-Marie Lopez-Cuesta, C2MA Mines d’Alès, France, outlined the importance of developing performance flame retardants for 3D printing. 3D printed objects show high fire risk, because objects are often thin wall but also because tests show that the 3D printed polymer is itself porous (includes air).
Tests have shown lower time to ignition and time to peak heat release but similar total heat release for 3D printed PLA objects, compared to the same object produced by injection molding. To be effective, FRs must be mixable with the polymer pellets used to obtain 3D printing filaments. PIN FR combinations of ammonium polyphosphate, melamine and nanoclays (montmorillonite and sepiolite) showed in tests to improve fire behaviour of 3D-printed PLA, but without achieving UL94 classified performance.