Synergistic Flame‐Retardant System of Melamine‐Coated Red Phosphorus/Deprotonated Phytic Acid for Enhancing the Fire Safety of Natural Rubber Latex

ABSTRACT The industrial production of flame‐retardant latex products remains a critical challenge in developing high‐performance composites. To address this issue, this study incorporates melamine‐coated red phosphorus (MRP) and the bio‐based flame retardant deprotonated phytic acid (PA) into natural rubber (NR) latex. The advantages lie in the good dispersion and compatibility of MRP‐PA in NR latex and the significant enhancement in flame retardancy of NR/MRP‐PA composites, even at low loadings. A series of flame‐retardant latex samples was prepared via acid coagulation using an industrially feasible process. The optimized composite, NR/20MRP4PA, demonstrates outstanding fire safety performance, achieving a limiting oxygen index (LOI) of 27.8%. Its peak heat release rate (PHRR) and total heat release (THR) are significantly reduced to 237.50 kW/m 2 and 39.74 MJ/m 2 , respectively. Residual char analysis reveals that the NR/20MRP4PA forms a dense and continuous char layer, which alters the decomposition pathway of the matrix during combustion. Furthermore, in terms of mechanical properties, the composite maintains a tensile strength of 6.2 MPa and an elongation at break of 815.3%, making it particularly suitable for applications that require high flexibility and strict flame‐retardancy standards. This work provides a feasible pathway for manufacturing flame‐retardant latex products and promotes progress toward commercial viability.