Inhibition mechanism of bio-based phytic acid chelate-mediated interfacial assembly of Mn and Ni: Elucidation by experiment of downward flame spread and analysis of thermal degradation with TG-IR-MS

Due to the increased risk of phosphate depletion, there is an increasing demand for low-phosphorus or bio-based phosphorus flame inhibitors. Therefore, two novel composites with biologically-based phosphorus sources that chelate transition metal ions were synthesized via assembly method, i.e., Mn-PMC and Ni-PMC, the structure and binding states of the composites were examined by SEM, TEM, FTIR, XRD, XPS, BET and TGA. The results indicated that Mn-PMC and Ni-PMC (ⅰ) are nanoscale materials with well dispersed, (ⅱ) have an amorphous structure and have sites that bind to other substances, (ⅲ) contain no halogen elements. Then the combustion inhibition experiments of downward flame spread and TG-IR-MS analysis revealed (ⅰ) that the inhibition efficiency of the two prepared inhibitors was higher than that of commercial phosphate-containing inhibitor ADP. Among them, Ni-PMC had the best suppression effect, and the flame of cellulose sample containing it would automatically extinguish after igniting with a smallest dosage, (ⅱ) two inhibitors reduced the laminar flame velocity and flame temperature. (ⅲ) their flame suppression mechanism was indicated as that the pyrolysis releases inert gas to dilute the free radical concentration. This work is helpful for the development of efficient transition metal fire extinguishing agents to replace traditional phosphorus resources.