Synthesis and Properties of Curcumin‐Based Phosphorus Containing Intrinsic Flame‐Retardant Epoxy Resin

To develop environmentally friendly alternatives to halogenated flame retardants while maintaining the fire resistance and mechanical properties of flame‐retardant epoxy resins (FREP), we prepared a phosphorus‐containing bio‐based reactive flame retardant (CFR) through an addition reaction between 9,10‐dihydro‐9‐oxa‐10‐phospha‐phenanthrene‐10‐oxide (DOPO) and curcumin. Comprehensive characterization confirmed the successful synthesis of CFR, and systematic investigations were conducted to evaluate its effects on FREP performance. The incorporation of 10 wt.% of CFR enabled the cured composite to achieve a V‐0 rating in the vertical burning test, along with an enhanced limiting oxygen index (LOI) of 33.3%. Moreover, compared to neat EP, EP‐CFR‐10 exhibited a 37.5% and 38.4% reduction in peak heat release rate (PHRR) and total heat release (THR), respectively, along with a notable 60.8% increase in char yield. In terms of mechanical performance, tensile tests confirmed that EP‐CFR‐10 had superior properties relative to pure EP, with the tensile strength increasing by 18.5%. Overall, the integration of CFR into EP imparted excellent fire resistance and thermal stability while preserving favorable mechanical characteristics.