Fabrication of Polyurethane-Based Foams With Incorporated “Waste” Glycerol From Biodiesel Synthesis and “Waste” Agricultural Residues (chopped rice hull fibers)

We are interested in fabricating green materials that could potentially be used in building construction applications. Ideally, the inputs to these materials would not lead to further deforestation, and rely minimally on nonrenewable fossil fuels.  To make a sustainable product, we aim to incorporate “wastes” from current industrial and agricultural processes.  The green building material will be a “sandwich” composite where foam will serve as the compressible, light-weight core, and a hemp/bioresin board will be the rigid, dense outer sheath.  The foam we have made is based on polyurethane chemistry where we have used modified castor oil as the polyol.  We have successfully incorporated “waste” glycerol that is a (~15 weight percent) byproduct of biodiesel synthesis into the foam.  We also incorporated waste agricultural residues such as chopped hay and rice hulls into the foam as a filler.  FT-IR spectroscopy and scanning electron microscopy revealed that the incorporation of these two “waste” components did not disrupt the polyurethane chemistry.  Furthermore, we measured the compression strength (using ASTM D3575-08) of these foams as a function of the percent of “waste” added and found some interesting behavior.  We also have successfully used a vacuum infusion method to make rigid boards from woven hemp fabrics and a “Bioresin” TM (from Entropy Resins, Inc.). Hemp was used because it is plant-based and it has one of the highest mechanical strengths among plant fibers.  Sandwich composite boards are now being assembled, and we are measuring their mechanical properties.  We envision that these boards can perhaps be utilized as substitutes for non-load bearing panels in the construction of green buildings.