Polyflavenoid tannin-furanic rigid foams have widespread industrial applications. The chemical and physical properties of the five main tannin-based foams are tested and compared in this paper. A TPS instrument measured the thermal conductivity of the tannin-based foams using the transient plane source (TPS) method. Results showed that the tannin foam containing formaldehyde and a low-boiling blowing agent (STD) had the highest thermal conductivity, and the foams without formaldehyde and surfactant (...