Thermo-Physical Analyses of Palm Oil Based Polyurethane Coating

Abstract

This research investigates the thermo-physical properties of thiol-ene UV curable palm oil urethane acrylate coating. Palm oil-based polyurethane (EPOUA) oligomer is synthesized from epoxidized palm oil by acrylation and isocyanation process. Then, the oligomer is mixed with 1,2-ethanedithiol (EDT) monomer and followed by di and tri-acrylate monomers to initiate thiol-ene reaction under UV radiation. The effect of different concentrations of EDT on the thermo-physical performances of palm oil polyurethane coating is studied. The sample is characterized with Fourier Transform Infrared Spectrophotoscopy (FTIR) to confirm the chemical interaction of EDT with the EPOUA and other monomers. The sample is further analyzed on its microstructure, thermal and physical properties using X-ray Diffraction (XRD), Differential Scanning Calorimetry (DSC), gel content, and water contact angle. The XRD results proved that the addition of higher EDT provides higher d-spacing and peak intensity reflected to higher molar mass and higher crosslinking density is taking place. This finding is also in line with the DSC results as higher curing peak and total heat (J g⁻¹) for curing observed at higher EDT concentration. The gel content and water contact angle also improve at higher amount of EDT resulting to a better crosslinking density and surface tension to the coating samples. The highest curing heat energy and gel content is at 2% thiol (0.42 J g⁻¹ and 85% respectively), while 4% EDT shows the highest contact angle (101.3°).