OPTIMIZATION STUDIES ON THE SYNTHESIS AND CHARACTERIZATION OF BIO-BASED EPOXIDIZED SOYBEAN OIL (ESBO)

There is an urgent need to replace petroleum based polymers by way of bio-based polymers. Bio-based polymers help in the reduction of fossil fuels usage, and improve economic and environmental concerns. Further, composites made using them become viable replacements for metal parts in the aerospace, marine, and automotive industries. The major sources for bio-based polymers are vegetable oils, which offer advantages such as being renewable, biodegradable, and abundant. It is the unsaturated double bonds in the vegetable oils that are converted for polymeric materials such as use in coatings and resin systems. Hence, this research focuses on synthesizing a completely bio-based polymer to achieve a high bio-content via an epoxidation process which uses soybean oil to produce a soybean based epoxy resin. The epoxidation process used in this study uses a chemical method that consists of using soybean oil with unsaturation (double bond) sites, carboxylic acid (formic acid) as the oxygen carrier, and hydrogen peroxide as the oxygen donor in converting the double bonds in the oil to epoxide groups. The desire to obtain high oxirane oxygen content (OOC) (epoxide group) is contingent on obtaining an optimum stoichiometric ratio for control purposes based on certain criteria. These criteria focus on comparing and varying the effect of temperature (at 50 and 60 degrees C), reaction time (at 2, 4 and 6 hours), and concentration of hydrogen peroxide (at 1, 1.5, and 2 molar ratio). These parameters are monitored to achieve an optimum system that would yield the highest oxirane oxygen content. The determination of the epoxide groups was performed through manual titration process using ASTM D1652-11. The highest percent oxirane oxygen content using formic acid was found to be 7.45, yielding a 98% conversion. Fourier transform infrared (FTIR) spectroscopy and rheology verified the presence of epoxide groups from ASTM D1652-11.