(688a) Eco-Foaming Lignin for Innovative Rigid Foams

Rigid lignin foams were prepared by a chemical-free baking method using kraft lignin as the sole resource. The preparation process involved cold-pressing kraft lignin powder into a solid block, heating the solid block to form a lignin foam, and finally curing and cooling the lignin foam to obtain an open-cell, rigid foam. Both the adsorbed water and water generated from dehydration of hydroxyl groups in the lignin served as the blowing agent in this baking method. It was found that as the moisture contents of lignin decreased, the foam densities increased, the mean bubble size decreased, and the bubble size distribution became narrower. Foam morphology showed an open cell structure and a wide cell volume distribution. The results suggest that controlling the moisture content in the feedstock allows for control of the pore structure of the lignin foam. Based on their unique properties, the lignin foam materials have great promise in many applications especially for core insulation materials of structural insulated panels (SIPs).