A Novel Phosphazene/Montmorillonite Flame Retardant Enhances the Fire Safety Rating of Natural Rubber

To address the flammability and achieve halogen‐free, high‐efficiency flame retardancy of natural rubber (NR) products, we successfully synthesized a novel phosphazene/montmorillonite flame retardant (PS@OMMT) through in situ coating of organically modified montmorillonite with cyclophosphazene derivatives. The synthesized PS@OMMT was compounded with NR to prepare the corresponding flame‐retardant NR composite materials (NMPRs). The morphology, chemical structure, and thermal stability of the synthesized PS@OMMT were systematically characterized. The synthesized PS@OMMT exhibited good dispersion ability in NR, and this material significantly improved the limiting oxygen index and UL‐94 rating of the NMPRs, effectively inhibiting heat release and smoke generation during the combustion process. A synergistic flame‐retardant mechanism of the PS@OMMT was proposed and discussed, which was based on a comprehensive analysis of the thermal decomposition behavior, gas release, and char residue characteristics after combustion of the NMPRs. This work provides a feasible strategy and reference for the development of high‐performance, environmentally friendly flame retardants as well as flame‐retardant rubber materials.