Tannin-based rigid foams: Characterization and modification

Tannin-based rigid foams are networked structures obtained by polycondensations of polyflavonoid tannins and furfuryl alcohol. They present a wide range of characteristics. Thus, there is the need to characterise the different kinds of tannin foams to better understand their physical behaviour and their chemical composition. Mimosa tannin, pine tannin and quebracho tannin bark extracts were used as building blocks. Foams modified by the addition of hydroxymethylated lignin, polyurethane and an industrial surfactant were also characterised. Water absorption, compression resistance, direct flame behaviour and foam cells dimensions were measured for each foam sample. The foams were characterised also by C-13 NMR analysis. Tannin-based rigid foams appear suitable for a wide range of applications. (C) 2008 Elsevier B.V. All rights reserved.