From the viewpoint of recycling of bio-based resources and environmentally friendly polymers, polyurethanes (PU) were prepared from polyethylene glycol (PEG) with bean-curd refuse (BCR) and diphenylmethane diisocyanate (MDI). BCR consists of protein, lipid, saccharide and ash. However, it is not known which component is most effective to improve the physical properties of PU's. In order to investigate the effect of the components of BCR on the physical properties of PU, PU's were prepared from each component of BCR and the mixture of components (called man-made BCR). Stress at break (σb) of PU's increased by increasing the polysaccharide components, while strain at break (εb) of PU's increased by increasing the lipid component. Glass transition temperature (Tg) of PU's increased by increasing the components of polysaccharide and lipid, and decreased by increasing the content of protein. These results suggested that chemical structure of the components of natural resources affected the physical properties of PU's. The physical properties of PU derived from BCR and man-made BCR were calculated by the equation of additive rule and these values agreed with those of BCR-PU.
