Application of Taguchi design to produce polyols based on castor oil derivatives with diethylene glycol

Abstract

Castor oil (CO) is one of the most valuable oils, because of its characteristics and potential use in synthesis.  A simple way to modify the castor oil structure is the transesterification reaction with an alcohol. Through this reaction, a renewable polyol could be produced and applied in the polyurethane industry.  In this study, the transesterification was done by KOH catalysis following a Taguchi experimental design.  The chosen alcohol was diethylene glycol (DEG) and the product components were estimated by GPC.  This chromatographic technique allowed establishment of the most favorable conditions to produce monosubstituted DEG or disubstituted DEG.  In the conditions suggested by the Taguchi design, the condition that favors monosubstituted DEG is 9:1 DEG:CO molar ratios, 200°C for 4 h and 0.5% KOH.  This condition leads to approximately 75% monosubstituted DEG and 11% disubstituted DEG in a mixture with the remaining acylglycerols.  The hydroxyl value of this product is 407, a high value for a product with a relatively low molecular weight.  These characteristics suggest that it can be used as a polyol for polyurethanes.