Polymeric Si-N PIN FR for polycarbonate

Functionalised polysiloxane 2% loading in polycarbonate (PC) achieved UL 94 V-0 (3.2 mm), PHRR -64% and total smoke -18%. Siloxane (4Si-4O-8H ring) was reacted with a silane (3-aminopropylmethyldiethoxysilane) and different benzaldehydes to give a silicon-nitrogen polymer with annexed benzene rings functionalised with 0 to 3 OCH₂ groups. This polymer was compounded into polycarbonate at 2% w/w. Results showed that more OCH₂ groups were present resulted in improved fire performance and also improved notched impact strength. The PC with Si-N polymer with benzene - 3 OCH₂ groups achieved UL 94 V-0 (3.2 mm) and peak heat release -64% and total smoke production -18% lower than neat PC, and also +190% notched impact strength at room temperature and + 72% at -25°C.

“Excellent flame-retardant polycarbonate composites with improved notched impact toughness via introducing imine-functionalized polysiloxane”, Y. Zhu et al., Composites: Part A 186 (2024) 108416, https://doi.org/10.1016/j.compositesa.2024.108416