BIODEGRADABLE POLYURETHANES FROM PLANT-COMPONENTS

Polyurethane (PU) sheets and foams having plant components in their ne twork were prepared by using the following procedure. Polyethylene gly col (PEG) was mixed with one of the following; molasses, lignin, woodm eal, or coffee grounds. The mixture obtained was reacted with diphenyl methane diisocyanate (MDI) at room temperature, and precured PUs were prepared. The precured PUs were heat-pressed and PU sheets were obtain ed. In order to make PU foam, the above mixture was reacted with MDI a fter the addition of plasticizer, surfactant (silicone oil), catalyst (di-n-butyltin dilaurate), and droplets of water under vigorous stirri ng. The glass transition temperature, tensile and compression strength s, and Young's modulus of the PU sheets and foams increased with an in creasing amount of plant components. This suggests that saccharide and lignin residues act as hard segments in PUs. It was found that the PU s obtained were biodegradable in soil. The rate of biodegradation of t he PUs derived from molasses and coffee grounds was between that of cr yptomeria (Cryptomeria japonica) and beech (Fagus sieboldi).