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Discipline: Technology and Engineering
Subcategory: Materials Science
Shatori Meadows - Tuskegee University
Co-Author(s): Mahesh Hosur, Alfred Tcherbi-Narteh, and Shaik Jeelani, Tuskegee University, Tuskegee, AL
Traditionally, polymers are synthesized from petrochemical by-products. The greenhouse gas emissions from petroleum based polymers make them unattractive options as there has been an increase in climate changes and adverse weather conditions. Additionally, they are non-degradable, creating issues when used as landfills. For these reasons and more, there is an urgent need to find an alternative source of polymeric materials by way of bio-based polymers. These bio-based polymers help in the reduction of fossil fuels and further improve economic and environmental concerns. Further, they have become a viable replacement for metals in the aerospace, marine, and automotive industries as they are resistant to corrosion. Hence, this research focuses on synthesizing a completely bio-based polymer using soybean oil to achieve a high bio-content via an epoxidation process that uses soybean oil to produce a soybean based epoxy resin. This epoxidation process uses the conventional chemical method that uses a carboxylic acid (formic or acetic acid) as the oxygen carrier, and hydrogen peroxide as the oxygen donor in converting the double bonds in the oil to epoxide groups. Determining an optimum stoichiometric ratio for high oxirane oxygen content is investigated taking into consideration the effect of using formic acid versus acetic acid as well as the effect of temperature (at 50 and 60 ºC), 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 the highest oxirane oxygen content. Determination of the epoxide groups was done through manual titration process using ASTM D1652-11. The highest percent oxirane oxygen content using formic acid of 7.45 (98% conversion) was achieved when using 2 molar ratio of hydrogen peroxide for a reaction time of 6 hours at a temperature of 50 ºC. Fourier transform infrared (FTIR) spectroscopy verified the presence of epoxide groups as determined by ASTM D1652-11 at 6 hours and possible side reactions at 2 and 4 hours, indicated by the disappearance of the epoxide groups. Rheological characterization plotting the viscosity versus shear rate indicated thixotropic behavior at initial shear rates, and further non-Newtonian shear thickening and shear thinning properties beyond 75 s-1. It is concluded that time, temperature, and variation in the concentration of hydrogen peroxide affect the epoxidation process while optimum conditions does not need to exceed 6 hours. This work is ongoing as additional work looks at the synthesis of epoxidized soybean oil using acetic acid. Future research involves investigating various modification techniques to further introduce more reactive groups in the optimum epoxidized soybean oil epoxy system for possible improvement of the oxirane oxygen content and subsequently improvement in its properties for future use in fiber reinforced composites.
Funder Acknowledgement(s): NSF-EPSCoR; NSF-CREST; Alabama Commission on Higher Education (ACHE)
Faculty Advisor: Mahesh Hosur, hosur@mytu.tuskegee.edu
Role: This research was perform solely by myself with advice from my advisor.
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