In this article, polyurethane resins were synthesized from liquefied benzylated wood and toluene diisocyanate (TDI)-trihydromethylene propane (TMP) prepolymer (as curing agent). The relations of their segmented structure and properties of were investigated. Results indicated that polyurethane resins made from benzylated wood solution have good mechanical and thermal properties. With the increase of curing agent amount from 23.8 to 53.51%, the degree of phase segregation increased, and under experimental conditions in this article, phase transition was de-tected with a curing agent amount of 69.9%. After this transition, the mechanical properties of polyurethane resins were improved. Thermal history treatment can also influence microstructure and thermal stabilities of polyurethane samples. (C) 2005 Wiley Periodicals, Inc.