Brigit Fassbender, Budenheim, presented developments in nitrogen and phosphorus inorganic (PIN) flame retardants for different polymers. These PIN FRs function by generating an intumescent char layer on the surface, which isolates the polymer from fire and also reduces smoke release. Widely used PIN FRs such as melamine cyanurate, melamine polyphosphate or ammonium polyphosphate offer good eco-toxicity properties and high thermal stability, but pose challenges in thin applications because the polymer content is insufficient to generate protective char (difficult to achieve UL94-V0 below 0.8 mm). Difficulties of compatibility between such inorganics and polymers can lead to migration of the FR to the surface (blooming). These challenges are addressed by adapting FR formulations, including specific coatings, for different polymers. These formulations can deliver intumescent fire performance, whilst conserving or even improving materials properties such as elasticity or elongation at break.
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