ACS applied materials & interfaces | 23 Oct 2015
AV Vinogradov, D Kuprin, I Abduragimov, G Kuprin, E Serebriyakov and VV Vinogradov
We report the new development of fire extinguishing agents employing the latest technology of fighting and preventing fires. The in situ technology of fighting fires and explosions involves using large-scale ultrafast-gelated foams, which possess new properties and unique characteristics, in particular, exceptional thermal stability, mechanical durability and full biocompatibility. We provide a detailed description of the physico-chemical processes of silica foam formation at the molecular level and functional comparison with current fire extinguishing and fighting agents. The new method allows to produce controllable gelation silica hybrid foams in the range from 2 to 30 seconds up to 100 Pa·s viscosity. Chemical structure and hierarchical morphology obtained by SEM and TEM images develop thermal insulation capabilities of the foams, reaching a specific heat value of more than 2.5 kJ/(kg·°С). The produced foam consists of organized silica nanoparticles as determined by XPS and X-Ray diffraction analysis with a narrow particle size distribution of about 10-20 nm. As a result of fire extinguishing tests, it is shown that the extinguishing efficiency exhibited by silica-based sol-gel foams is almost 50 times higher than that for ordinary water and 15 times better than that for state-of-the-art firefighting agent AFFF(aqueous film forming foam). The biodegradation index determined by the time of the induction period was only 3 days, while even for conventional foaming agents this index is several times higher.
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