Flexible polymeric biomaterials from epoxidized soybean oil, epoxidized oleic acid, and citric acid as both a hardener and acid catalyst

摘要

Flexible bio-based polymeric materials were produced by combining epoxidized soybean oil (ESO), aqueous citric acid solutions, and varying amounts of epoxidized oleic acid (EOA), followed by heating at 95 degrees C for 24 h. Starting materials were analyzed by way of proton nuclear magnetic resonance (H-1 NMR), to confirm the conversion of double bonds in soybean oil or oleic acid to epoxides. Attenuated total reflectance Fourier-transform infrared spectroscopy (ATR-FTIR) was used to confirm the reaction of epoxide groups with citric acid and/or EOA. Tensile testing was done to determine the differences in Young's modulus between samples with varying amounts of EOA. Stiffness increased with decreasing EOA content. The stiffest sample (0% EOA) and most elastic sample (30% EOA) had a Young's modulus of 1.43 +/- 0.19 MPa and 0.064 +/- 0.004 MPa, respectively. Differential scanning calorimetry (DSC) showed that the glass transition temperature was below room temperature for all samples, and decreased with increasing EOA content.