Biobased foams from condensed tannin extracts from Norway spruce (Picea abies) bark

•Characterization of tannins extracted from Norway spruce bark produced at pilot scale.•The presence of non-cellulosic sugars affects markedly the foaming process.•Condensed tannins extracted from Norway spruce bark were used for the acid-catalyzed polycondensation of foams.•Spruce foams were characterized and compared with other procynidin-type foams.

Different kinds of tannin-based foams were developed in the recent past with fisetinidin/robetinidin-type tannins extracted from mimosa (Acacia mearnsii) or quebracho (Schinopsis lorentzi) bark; or procyanidin-type tannins from pine (Pinus pinaster and Pinus radiata). These biobased porous products revealed excellent properties similar to their synthetic counterparts in many applications. Norway spruce (Picea abies) bark is another large potential source of procyanidin-type tannins. In this study rigid and homogeneous foams were produced from purified tannins containing at least 80% of polyflavonoid condensed tannins. This paper deals with the study of spruce tannins reactivity for rigid foam formulations. Characterization results have point out their very good mechanical resistance (σ > 0.08 MPa), and low thermal conductivities (λ < 0.045 W/m/K) at low densities (d < 50kg/m3).