Physical properties of water-blown rigid polyurethane foams from vegetable oil-based polyols

Fifty vegetable oil-based polyols were characterized in terms of their hydroxyl number and their potential of replacing up to 50% of the petroleum-based polyol in waterborne rigid polyurethane foam applications was evaluated. Polyurethane foams were prepared by reacting isocyanates with polyols containing 50% of vegetable oil-based polyols and 50% of petroleum-based polyol and their thermal conductivity, density, and compressive strength were determined. The vegetable oil-based polyols included epoxidized soybean oil reacted with acetol, commercial soybean oil polyols (soyoils), polyols derived from epoxidized soybean oil and diglycerides, etc. Most of the foams made with polyols containing 50% of vegetable oil-based polyols were inferior to foams made from 100%, petroleum-based polyol. However, foams made with polyols containing 50%, hydroxy soybean oil, epoxidized soybean oil reacted with acetol, and oxidized epoxidized diglyceride of soybean oil not only had superior thermal conductivity, but also better density and compressive strength properties than had foams made from 100% petroleum polyol. Although the epoxidized soybean oil did not have any hydroxyl functional group to react with isocyanate, when used in 50 : 50 blend with the petroleum-based polyol the resulting polyurethane foams had density versus compressive properties similar to polyurethane foams made from 100% petroleum-based polyol. The density and compressive strength of foams were affected by the hydroxyl number of polyols, but the thermal conductivity of foams was not. (c) 2007 Wiley Periodicals, Inc.