Synthesis and Functional Evaluation of Soy Fatty Acid Methyl Ester Ketals as Bioplasticizers

A facile synthesis of the soy fatty acid methyl ester ketal has been accomplished using acetone in the presence of catalytic anhydrous ferric chloride starting from commercially available soy biodiesel (soy fatty acid methyl ester) after evaluating various synthetic procedures. The soy ketal product was fully characterized by nuclear magnetic resonance, infra-red and chromatography. The physical and analytical properties of soy ketal as determined by thermogravimetric analysis, viscosity acid and saponification values are acceptable for plasticizer applications. Soy ketal was compounded with polyvinyl chloride for evaluation of plasticizer properties such as efficiency, gelation, viscosity, volatility, thickening/aging behavior and stability. The thickening and aging behaviors of the soy ketal bioplasticizer are better than those of petroleum-based plasticizers such as diisononyl phthalate and diisononyl-cyclohexane dicarboxylate, but they need improvement in the areas of thermal stability and water extractability.