Raw soybean oil was hydroxylated with acetic acid and hydrogen peroxide to prepare soy-based polyols of various functionalities. These polyols were reacted with a modified diphenyl methane diisocyanate (Isonate 143L) to make polyurethane networks. The sol fractions decreased as the hydroxyl number of the polyol increased, and the glass-transition temperatures increased with the hydroxyl number, as did the rubbery plateau storage modulus and Young's modulus of the networks. When the glass-transition temperatures of each network were plotted as a function of the polyol's hydroxyl number, a linear relationship was observed over the range investigated. TNs trend closely matched that of our previous work with soy-based polyurethane networks. A second series of networks was prepared with the same polyols but with different isocyanates. The nature of the crosslinker was shown to somewhat influence the sol fractions, glass-transition temperatures, and stress-strain behavior of the networks. A linear relationship was recorded between the storage modulus at 125 degrees C of a network and the average functionality of the polyol from which it was synthesized. Finally, two separate polyurethane networks were prepared through the blending of two polyols: one based on petroleum and the other based on soy. These networks were also characterized, and the compatibility of each blend was addressed. (c) 2007 Wiley Periodicals, Inc.