Abstract: Methods and compositions for forming polyurethane foam. A method for manufacturing an aromatic polyester polyol comprises heating a glycol, a dicarboxylic acid or ester, functionality enhancing agent, and a natural oil to about 480° F. to form a reaction product, allowing the reaction product to cool to about 140° F., and adding additional glycol to form an aromatic polyester polyol composition, wherein the total glycol comprises less than about 36 weight percent of the polyol composition. An aromatic polyester polyol composition comprises a glycol, a dicarboxylic acid or ester, functionality enhancing agent, and a natural oil, wherein the total glycol comprises less than about 36 weight percent of the aromatic polyester polyol composition.

Abstract: Methods of making aromatic polyester polyols that are suitable for use with hydrocarbon and hydrofluorocarbon blowing agents. The polyols are made by reacting polyethylene terephthalate, dissolved in a solution comprising a plurality of glycols, with a natural oil. The natural oil reacts into the polyol backbone at a specific temperature. Aromatic polyester polyols that are suitable for use with hydrocarbon and hydrofluorocarbon blowing agents. The polyols are made from polyethylene terephthalate and a natural oil. The polyols exhibit low hydroxyl numbers and low viscosities, and hydrocarbons and hydrofluorocarbons blowing agents are soluble in these polyols. A method for making foam using the polyols of the present invention. The method includes reacting a polyol of the present invention, mixed with other polyol components, with an isocyanate component.