Exploiting the Use of Salvia Hispanica L. (chia) Oil as a Renewable Raw Material to Produce Air-Drying Alkyd Resins: A Comparative Study

Abstract

This work addresses a comparative study focused on the synthesis of alkyd resins from different renewable resources such as chia, castor and palm vegetable oils through the alcoholysis–polycondensation process. The formed alkyd resins are analyzed by Fourier transform infrared (FTIR), ¹H NMR, and ¹³C NMR. Besides, intrinsic viscosity and gel permeation chromatography (GPC) assays are conducted to evaluate the differences between the obtained resins focusing on their molecular weight and physicochemical properties. FTIR shows a satisfactory conversion from vegetable oils to alkyd resins. Both ¹H NMR and ¹³C NMR indicate that alkyd resins are successfully synthesized. The values for molecular-weight dispersity (Ð_M) obtained for the resins are 2.3, 1.3, and 1.7 from chia, palm, and crude castor, along with the weight-average molecular weight (M_w) of 4516, 1025, and 2451 g mol⁻¹, respectively. The chia alkyd resin shows a 571.92 cP and is the highest viscosity obtained. It is also observed that an increase in phthalic anhydride can increase the molecular weight of the alkyd resin. This comparative study indicates that chia oil alkyd resin has enormous potential to be employed as a surface coating agent.