Development of a phytate-modified sodium bicarbonate additive for non-toxic flame retardancy in cellulose paper

Sodium bicarbonate (NaHCO 3 ) was functionally modified using transition metal-phytic acid (PA) complexes, successfully synthesizing two composite materials, namely NaHCO 3 -P@Mn and NaHCO 3 -P@Ni. These composites were mixed with cellulose fibers in an aqueous medium to prepare flame-retardant paper, whose structure and properties were analyzed via characterization. The results showed that the original NaHCO 3 exhibited a square morphology with a smooth surface, having a diameter of 100–200 μm. After being encapsulated by phytate microcapsules, the surface roughness of the particles increased and their size decreased significantly, among which the particle size of NaHCO 3 -P@Mn was only 1 μm. In the early stage of combustion, the synergistic effect between bio-based phosphorus and transition metals played a key flame-retardant role. Performance tests indicated that the flame-retardant efficiency of both composites was improved by more than 50 % compared with commercial ammonium dihydrogen phosphate. Notably, when the addition concentration of NaHCO 3 -P@Ni was 37.65 × 10 −5 mol/g, it enabled the cellulose paper to achieve self-extinguishing behavior. In conclusion, the NaHCO 3 -P@Mn and NaHCO 3 -P@Ni composites can significantly enhance the flame-retardant performance of paper while endowing it with self-extinguishing properties, providing a new idea for the preparation of high-efficiency and environmentally friendly flame-retardant paper.