Supramolecular Flame‐Retardant Synergist in Combination with Aluminum Diethylphosphinate: A New Strategy for Improving the Flame Retardancy and Mechanical Properties of Natural Rubber Composites

ABSTRACT Natural rubber (NR) has high elasticity, high tensile strength, and excellent processing performance, but its high flammability limits its application. Adding aluminum diethylphosphinate (ADP) to natural rubber can improve its flame retardancy, but its mechanical properties will be greatly reduced. Therefore, it is still a challenge to improve the flame retardancy of NR while maintaining its mechanical properties. In this study, a new flame retardant synergist mDT@Ni was synthesized, which was compounded with ADP and added with NR to study the effect of the composite system on the flame retardancy and mechanical properties of NR. The results showed that compared with pure NR, the oxygen index of NR composites with 0.75 phr mDT@Ni and 19.25 phr ADP increased from 19.2% to 25.5%, the total heat release (THR) decreased by 21.1%, and the maximum heat release rate (pHRR) decreased by 25.7%. At the same time, its mechanical properties have also been improved; the tensile strength and elongation at break increased by 14.5% and 18.2%, respectively. In addition, the flame retardant mechanism was studied in detail by residual carbon characterization and TG‐FTIR test.