Preparation of <scp>ABD</scp>‐@<scp>MMT</scp> Nano‐Flame Retardant Toward Fire‐Safety and Stable Mechanical Properties for Aramid‐Reinforced Epoxy Resin Composites

ABSTRACT The mismatch of flame retardancy and mechanical properties is still a challenge for developing high‐performance epoxy resin (EP) and its aramid fiber (AF) composite. In this study, bi‐DOPO compound (ABD) was prepared by reacting DOPO with acrolein, Na‐MMT was modified by octadecyltrimethylammonium chloride to prepare organic MMT(@MMT), and finally, ABD‐@MMT nano‐flame retardant was prepared by using ABD to intercalate @MMT to solve this problem. After introducing ABD‐@MMT into AF/EP composites, it exhibited good thermal stability, excellent flame retardancy, and enhanced mechanical properties. The intercalation and exfoliation of the @MMT layer within the ABD and EP matrix indicated a uniform dispersion of the flame retardant. Especially for the sample of 3%ABD‐@MMT/AF/EP composites, the limiting oxygen index (LOI) value increased from 23.8% to 34.7% accompanied by the V‐0 rating in the UL‐94 test. Scanning electron microscopy (SEM) analysis of residual carbon postcone calorimetry test and the degree of graphitization after muffle calcination supported the superior flame retardant properties of ABD‐@MMT nanocompounds. Furthermore, the tensile strength of 3%ABD‐@MMT/AF/EP composites measured at 38.3 MPa, representing an 8.5% increase compared to 3%ABD/AF/EP, only decreased by 7% compared to pure AF/EP composites. The incorporation of ABD‐@MMT improved both the burning behavior and mechanical properties of the composite, reflecting reduced burning intensity, increased tensile strength, and impact strength. This study presents a novel approach for developing AF/EP composites with enhanced mechanical strength and flame retardancy.