Development of a double-network gel foam based on sodium carboxymethyl cellulose with enhanced extinguishing and re-ignition resistance performance for tank fires

Traditional fluorinated foams (AFFF/FFFP), widely used for liquid fire suppression, suffer from poor thermal stability, re-ignition propensity, and often contain environmentally harmful fluorocarbon surfactants. This study developed an interpenetrating double-network gel foam (IDNGF) using non-fluorinated surfactants (AEG and AOS), gelling agent (CMC-Na and Na₂SiO₃), and crosslinking agent (AlCit). Orthogonal experiments optimized the foam expansion ratio and water retention. The optimal formulation—0.6 wt% AOS/AEG (1:9), 2.2 wt% Na₂SiO₃, 0.14 wt% CMC-Na, and 1.0 wt% AlCit—produced homogeneous foams with enhanced thermal stability due to the formation of a CMC–Al ³⁺/silicate double-network structure. Thermogravimetric analysis revealed a significantly higher complete evaporation temperature than conventional FFFP. Reactive forcefield molecular dynamics (ReaxFF-MD) simulations identified orthosilicic acid and aluminum-containing oxides as key pyrolysis products. Fire extinguishing and re-ignition existence experiments demonstrated that IDNGF reduced extinguishing time by 3.6% relative to FFFP while significantly extending the burnback time to 603 s—a 76.3% improvement. These results highlight the potentil of using IDNGF as a high-performance, re-ignition-resistant, and sustainable fire suppression agent.