▎ 摘　　要

Enhancing the flame retardancy with minimal impact on the mechanical and thermal performances of polymers remains a challenge. This study synthesized a phosphorus/nitrogen-containing silane compound (D) using polyformaldehyde, KH-550, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) as raw materials through the Kabachnik-Fields reaction. After that, D was grafted onto the surface of graphene after hydrothermal treatment to obtain a nano hybrid flame retardant (D-GR). And D-GR/EP composites exhibited good flame resistance (LOI = 30.1% and UL-94 reaches the V-1 rating) even if the load on D-GR was 1 wt%. Indeed, the total heat release, the peak heat release rate (PHRR), and the total smoke release of 1% D-GR/EP dropped by 13.54%, 28.62%, and 44.32%, respectively, in comparison to pure EP. The mechanical performance of 1% D-GR/EP was effectively maintained, as indicated by the results of impact, tensile and flexural tests. A systematic evaluation indicated that the accession of D-GR effectively inhibited smoke and heat releases that are ascribed to the synergistic effect of phosphorus/nitrogen-containing silane compound and graphene. In this study, a facile method was provided for the synthesis of halogen-free flame-retardant epoxy composites with superior performances. The combustion products of the as-prepared composites complied with green and environmental protection standards.