Phytic acid/sodium alginate/silicon dioxide composite aerogel with high thermal stability and excellent flame retardancy

This study presents the preparation of a novel composite aerogel material with superior thermal insulation and flame-retardant properties. Using fly ash-based silica aerogel particles as fillers, sodium alginate (SA) as the skeleton, and phytic acid (PA) as the flame retardant, PA/SA/SiO 2 (PSS) composite aerogels were successfully synthesized through a sol-gel process followed by freeze-drying. The PSS aerogels were characterized for their thermal properties using hot-disk thermal analysis, limiting oxygen index (LOI) tests, and other analytical techniques. The experimental results demonstrated that the composite aerogel exhibited low thermal conductivity, ranging from 0.0330 to 0.0380 W m −1 K −1 . The PSS composite aerogels achieved a maximum limiting oxygen index of 50.3%, and all samples satisfied the UL-94 V-0 rating with immediate self-extinguishing behavior. Physical cross-linking of PA, SA, and SiO 2 within the composite structure was confirmed through additional analyses. These all indicated the potential of the prepared aerogels for applications in building thermal insulation, high-temperature thermal protection, and fire-resistant materials.