Posted on 15/05/2023 in Fire Safety 2023
Testing new silicon – nitrogen PIN FRs

Silylamine and siloxyamine compounds showed flame retardancy in PP, PE and epoxy and synergy with P FR. Seventeen different N-Si and N-O-Si were synthesised, based on phthalimide (reacted to silyphthalimides or siloxyphthalimides) or on pyromelletic diimides. These were tested as PIN flame retardants in polypropylene films, linear low-density polyethylene and in epoxy resin. Sterical hindrance in the compounds (presence of bulky groups in the molecule) improved their thermal stability, facilitating processing. In each polymer tested, one or two (only) of the nitrogen silicon compounds at low loadings in combination with a spirocyclic phosphonate PIN FR achieved UL 94 V-0 (1.6 mm). The flame retardant mechanisms were identified as release of aminyl, silyl and oxygen-centred radicals acting in the gas phase and also causing earlier and enhanced activation of the phosphorus PIN FR, release of inert nitrogen gas and contribution of silicon to charring. pinfa notes that possible eco/tox safety of these new molecules should be assessed before further development.

“Synthesis of silylamine and siloxyamine compounds: A novel approach to flame retardancy of polypropylene and Epoxy resins”, T. Ääritalo et al., Polymer Degradation and Stability 211 (2023) 110336,

Share This