Schiff Base Derivative Flame-Retardant Endowing Epoxy Resin with Toughness, Transparency, and High Flame Retardancy

In this study, a novel phosphorus containing flame retardant SMAE was prepared through a nucleophilic addition of N,N'-bis (salicylidene) ethylenediamine (SAED) and phenyl hypophosphite, which can dissolve well in epoxy resin and belongs to molecular level flame retardancy. By using SMAE as a co-curing agent and DDM to cure epoxy resin, EP/SMAE composites with excellent flame retardancy and good mechanical properties were obtained. As the dosage gradually increases, the limited oxygen index (LOI) values continue to increase. At a 5% dosage, the LOI value can reach 39.7% and pass UL 94 V-0. It is observed that SMAE mainly exerts blowing-out effect in EP. In addition, the use of SMAE as a co-curing agent can improve the impact strength of EP, and the impact strength of 5% SMAE/EP can reach 14.15kJ/m2, which is 25% higher than that of pure EP.