A bifunctional modifier endowing epoxy resin with outstanding flame retardancy and high impact strength

Abstract The flammability and brittleness are two major shortages of epoxy resin (EP). Normally, adding flame retardants can deteriorate the mechanical property of EP. Herein, in this work, a reactive flame retardant (DPPO‐TES) containing both Si and P was synthesized and incorporated into EP. When the content of P is only 1.0 wt%, the LOI of the modified EP (DPPO‐TES/EP) reaches to 33.2%, UL‐94 passes V0, THR and pk‐HRR are 377.6 kw/m 2 and 103.5 MJ/m 2 , respectively, which is attributed to the high flame‐retardant efficiency in both condense phase and gas phase. In addition, the flexible SiOSi chains in the structure can significantly improve the impact strength of DPPO‐TES/EP. Therefore, as a bifunctional modifier, DPPO‐TES has a wide application prospect for EP materials.