Preparation of NaHCO3 fire extinguishing agent with perfluoropolyether groups to inhibit rapid re-ignition of Class B fires

To enhance the fire suppression effectiveness of dry powder extinguishing agents against Class B fires, the environmentally friendly surface modification of dry powder fire extinguishing agents using long-chain perfluoropolyether silanes (LCPS) was designed to modify the extinguishant. LCPS was synthesized by combining perfluoropolyether methyl ester (PME, Mw=4000 g/mol) and N-(β-aminoethyl)-γ-aminopropyltriethoxysilane (AAPS). A novel hydrophobic and oleophobic ultrafine dry powder fire extinguishing agent (LCPS-Na) was obtained by the introduction of LCPS into tetraethyl orthosilicate (TEOS)-modified ultrafine NaHCO3 powder (Na-UDP). The contact angles of water (WCA) and oil (OCA) on LCPS-Na are 151.4° and 145.8°, respectively. The hydrophobicity and oleophobicity of LCPS-Na are determined to be 94.2% and 85.6%, respectively. Moreover, the required concentrations of LCPS-Na powder to extinguish n-heptane and aviation kerosene fires are found to be 38.3 g/m3 and 39.7 g/m3, respectively, with a reduction of 31.6% and 31.0% compared to that of Na-UDP. The rekindling time for aviation kerosene after fire suppression was significantly prolonged to 40.6 s compared to Na-UDP (0.20 s), owing to the superior floating capability of LCPS-Na.