Synthesis and Characterization of Soyhull Glycerol Derived Rigid Polyurethane Foams

Rigid polyurethane foams are suitable construction materials because of their excellent thermal insulating properties and dimensional stability. However, at present these foams find limited use in the construction insulation foam market. The major hindrance to their wider use in this application is the cost. This hindrance can be significantly reduced through the use of inexpensive renewable raw materials. The use of two low cost materials, digested soyhulls and glycerol was examined as replacement for polyols in water blown rigid polyurethane formulations. The incorporation of the soy hulls in the water blown polyurethane formulation increased density and while the addition of glycerol is expected to increase cross linking and rigidity. As a first step towards use of soyhull in urethane formulation, the cellulose, hemicellulose, and lignins present in soyhull were subjected to a hydrothermal treatment. The treatment increases the number of reactive hydroxyl groups and enhances compatibility and interactions of soyhull with isocyanate. The soyhull containing foams and control foams without soyhull were subjected to a battery of mechanical tests. The results show that the polyurethane foams produced with treated soyhulls are not only cost competitive, but also exhibit superior mechanical properties. It is expected that these foams would be more biodegradable and environmentally friendly.