Recyclability of tannin-furanic foams

•Tannin-Furanic foams can be ground to powder and used as additive for new foams.•Replacing up to 10% of tannin with recycled material, does not decrease strength.•More than 25% replacement is not possible, as the foaming is disturbed.•Leaching shows, that the recycled material is incorporated in the polymer. Tannin-furanic foams are biogenic, lightweight material comprising of up 95% renewable resources. Replacing 5 to 30% of the tannin powder in the formulation for new foam with finely grinded, recycled tannin-furanic polymer powder was investigated. While 5% and 10% of recycled material did not have a significant influence on the mechanical properties (bending strength, modulus of elasticity, tensile strength and compression resistance) a slight decrease is observed for 15 to 25% replacement, but within these groups, results are not significantly different. An overall decrease of 30% for mechanical properties was observed for foams made with 15% to 25% recycled material. The addition of 30% recycling material in the production of tannin foams is not feasible, as the foaming process is disturbed.