Assessment of Epoxidized Isobutyl Fatty Esters from Soybean Oil Distillates as Biobased Plasticizers

This study evaluated the production and performance of biobased epoxidized isobutyl esters (EIE) as sustainable plasticizers for polymers, aiming to support circular economy models within the chemical industry. EIE were synthesized through the esterification of isobutyl alcohol with oleic and linoleic acids as well as soybean oil deodorizer distillates (SODD), followed by subsequent epoxidation. The plasticizing effect of epoxidized isobutyl oleate, linoleate, and soyate was assessed by studying their mechanical and thermal properties and performing Dynamic Mechanical Analysis (DMA) on PVC films prepared at a fixed content of 70 phr using the solvent casting method. The chemical structure of the films was identified by Fourier transform infrared (FTIR) spectroscopy while the permanence of the plasticizers was investigated through migration and volatility tests. Finally, barrier properties such as water vapor permeability and migration were evaluated alongside surface characteristics such as contact angle and transparency by UV–visible spectroscopy. Dioctyl phthalate (DOP) and epoxidized soybean oil (ESO) were used as reference commercial plasticizers. Among the different EIE, epoxidized isobutyl soyate (EIS) showed remarkable results such as high elasticity (500%), high thermal stability, tensile strength (11.2 MPa) comparable to the reference plasticizers, and high plasticizing efficiency (106.2%). However, barrier properties, such as water vapor permeability and migration, were affected by the composition of this epoxidized ester. Overall, EIE exhibited moderate migration rates which limit their use as general purpose PVC plasticizers, but they might be effectively used for low temperature applications and as coplasticizers for different polymers.