Microporous nitrogen-boron compound for epoxy-based composites with improved flame retardancy, toughness, dielectric properties, transparency, and UV shielding

Epoxy-based composites (EP composites) have long been essential in a range of thermoset applications. However, the increasing demands of emerging technologies call for multifunctional EP composites with enhanced properties. In this study, we prepared a highly effective microporous compound, BPT, containing nitrogen and boron to endow EP composites with multifunctionalities. The incorporation of 8 wt% BPT into EP composite increases the limiting oxygen index to 28.8 % and upgrades the UL-94 rating to V-0, due to the formation of a protective char layer that inhibits heat and oxygen transfer. Cone calorimeter tests demonstrate a remarkable reduction in peak heat release rate and total heat release by 55 % and 33 %, respectively. Moreover, the EP/BPT composite exhibits a 38 % reduction in total smoke production, a 45 % decrease in smoke production rate compared to the control EP. Mechanical properties are also significantly improved, with impact strength increasing from 9 kJ/m² to 12.4 kJ/m². Additionally, the EP/BPT composite maintains high transparency, effective UV shielding, and reduced dielectric constant and loss. This multifunctional additive, synthesized through an efficient and practical method, offers a promising solution to fabricate advanced multifunctional EP composites.