Facile fabrication of high-performance epoxy systems with superior mechanical properties, flame retardancy, and smoke suppression

The realization of high-performance thermosetting polymers with superior mechanical properties, flame retardancy and smoke suppression is very necessary but not yet implemented. Herein, a flame-retardant curing agent (BICPD) combining cyclotriphosphazene and phosphaphenanthrene groups was synthesized, and used to prepare high-performance, flame-retardant epoxy (EP/BICPD) systems. Our results showed that the EP/BICPD systems began to cure at 110°C and solidify rapidly under heating. In comparison to the common epoxy system, the EP/BICPD thermosets exhibited improved glass transition temperature and mechanical properties. Most impressively, the EP/BICPD thermosets possessed outstanding flame retardancy and smoke suppression. The EP/BICPD-20 thermoset achieved the LOI value of 37.7% and passed the UL94 V-0 rating. Additionally, compared with the common epoxy thermoset, the peak of heat release rate (pHRR) and total smoke production (TSP) of EP/BICPD-20 thermoset were reduced by ~70.0% and ~43.4%, respectively. The significant enhancements in flame retardancy and smoke suppression was mainly due to the collaboration of cyclotriphosphazene and phosphaphenanthrene in condensed and gaseous phases. Therefore, the high-performance EP/BICPD systems with high glass transition temperature, satisfied mechanical properties, superior flame retardancy and smoke suppression showed profound scientific and industrial significance.