Synthesis and characterization of epoxidized soybean oil / diisocyanate thermoset polymers

In this study, novel vegetable oil based thermoset polymers were synthesized from Epoxidized Soybean Oil (ESO) with several diisocyanates, methylene diphenyl diisocyanate (MDI), toluene diisocyanate (TDI), isophorone diisocyanate (IPDI). The characterization of polymers was done with FTIR spectroscopy. Enhancement of the chemical characterization was done with model compounds synthesized with ESO and phenyl isocyanate by 1H NMR and 13C NMR. Synthesis of polymers and model compounds were conducted in the presence of basic catalyst 1,4diazabicyclo [2.2.2] octane (DABCO) and acidic catalyst Antimony(III) chloride (SbCl3). Results showed that oxazolidone, urethane, isocyanurate, urea, biuret and allophonate groups were obtained varying amounts depending on the reaction conditions. Mechanical properties of polymers were analyzed with TGA (Thermogravimetric Analysis), swelling, compression and surface hardness tests. Thanks to the isocyanurate, biuret and allophonate groups, crosslink density of polymers are high and 5-membered oxazolidone rings gave rigidity to polymers that provide the comparable mechanical properties with commercial polymers. Compression strength 55 MPa for MDI polymers, compression modulus was 308 MPa and surface hardness was 70 shore D units.For one sample, leaching test was done and shows 97 % yield for polymerization was obtained.