Flammability assessment of tannin-based cellular materials

Fire retardance of highly porous tannin-based rigid foams formerly suggested as new, ecological, insulation materials, has been investigated in detail. For that purpose, one standard composition was tested using samples having five different bulk densities. Besides, for one given median density, three foams whose formulation has been modified by incorporation of boric and/or phosphoric acid were investigated as well. The parameters measured were the time to ignition, the critical heat flux for ignition and the heat release rate. All led to the conclusion that such foams present outstanding fire retardance. The tests were done blindly to avoid any interpretation bias. No significant differences could be observed when materials of standard composition but having different bulk densities were tested, or when testing modified foams. While modified foams showed slight differences, it was not possible to correlate these differences to higher fire performance.