Construction of a Synergistic Flame Retardant SiO ₂ /CoNi-DH-PA for Enhancing the Fire Safety of Epoxy Resin

In view of the problem that epoxy resin (EP) cannot achieve effective flame retardancy, smoke and toxic gas suppression functions in fire, and poor interface compatibility with flame retardants, a core-shell structure with SiO 2 as the nucleus was designed, and a new multicomponent flame retardant was prepared by introducing Ni and phytic acid using metal-organic frameworks (MOFs) as precursors. After mixing and curing with EP, the SiO 2 /CoNi-DH-PA/EP was obtained. With only 5% SiO 2 /CoNi-DH-PA added, the peak heat release, total smoke production and total CO production of EP composites are reduced by 63.72%, 31.88% and 63.74%, respectively, and the residue yield increased from 15.05% to 24.40%. It has been verified that SiO 2 , Co–Ni bimetallic ions and phytic acid have synergistic effects, which can induce and catalyze the formation of a complete and dense carbon layer. This significantly reduces the heat release, smoke and toxic gas production, thereby reducing the fire hazard of EP. Additionally, the SiO 2 /CoNi-DH-PA/EP ensures good mechanical properties.