A novel P, N doped organic-inorganic hierarchical core-shell nanostructures: Reducing the fire risk of epoxy resin

The wide application of epoxy resin (EP) causes a great potential fire risk to humans and the environment. To effectively reduce the fire risk of EP, we designed a novel P, N-doped organic-inorganic hierarchical core-shell nanostructure (BN@PEI@UiO-66@PPA). Encouragingly, with only 2 wt% of BN@PEI@UiO-66@PPA, the peak heat release rate (PHRR) and total heat release (THR) were reduced by 47.2 % and 47.9 %, respectively, compared with those of pure EP, indicating a considerable enhancement in flame retardancy. The peak smoke release rate (PSPR), total smoke production (TSP), peak CO production rate (PCOPR), and peak CO2 production rate (PCO2PR) were significantly reduced by 46.0 %, 52.7 %, 72.1 %, and 75.1 %, respectively, compared with those of pure EP, indicating a significant reduction in fire toxicity. In addition, the mass of the char residue of BN@PEI@UiO-66@PPA/EP increased by 185.3 %, and the graphitization degree and thermal stability of the char were significantly improved. The results indicate that the various components in BN@PEI@UiO-66@PPA were functionally different and cross-assisted to form dense P-N-C char with high graphitization and high thermal stability, which effectively improved the fire safety of EP. This work provides a new reference for the construction of multi-component hierarchical structures to optimize their application in the field of fire safety of polymer composites.