Polyols from Condensed Tannin Enriched Extracts for Rigid Polyurethane Foam Production

A condensed tannin enriched extract from Grey alder bark was completely liquefied using the batch solvent free oxypropylation process in a high pressure reactor. The obtained polyols were characterized in terms of their composition, functionality, viscosity, and reactivity towards isocyanate. The main constituents of the obtained polyols included high functional polyphenolics based copolymers and low functional constituents – carbohydrate derived products based copolymers and polypropylene glycols. This structure is important for governing the balance between the rigidity and elasticity of polyurethane networks. The polyols were successfully tested in rigid polyurethane foam compositions. Closed cell foams with a density of about 45 kg·m -3 were produced.