Application of aminotrimethylphosphonic acid modified starch‐based flame retardant in cellulosic paper

Abstract The development of green and efficient bio‐based flame retardants is very important for the development of flame‐retardant cellulosic paper. In this study, a novel type of starch‐based synergistic flame retardant (SAPU) was prepared using corn starch as carbon sources, amino trimethylphosphonic acid, and urea as phosphorus and nitrogen sources through the one‐pot method. Subsequently, the flame‐retardant cellulosic paper was prepared by impregnation, and the flame retardancy of the cellulosic paper was evaluated by vertical combustion, limiting oxygen index (LOI), and thermogravimetric analysis. The results demonstrated that the SAPU exhibited a favorable flame‐retardant effect on cellulosic paper. At a concentration of 25.0%, the vertical burning residue of flame‐retardant paper accounted for 49.16% of the total length of the paper sample, while the LOI was 39.4%. The tensile strength and burst index of cellulosic paper were found to be decreased by 6.36% and 19.1%, respectively, in comparison to the base paper. Conversely, the ring crush strength was observed to be increased by 156.2%. The carbon residue rate at 700°C under a nitrogen atmosphere rose from 11.56% of the base paper to 28.77% of the flame‐retardant paper. The flame‐retardant SAPU effectively improved the thermal stability of cellulosic paper.