Structure-property correlation study of bio-based multifunctional vinyl ester resin in presence of methacrylated lignin model compounds

Diels-Alder adduct of gum rosin and maleic anhydride (MPA) were treated with trimethylolpropane to obtain trimethylolpropane modified maleopimaric acid adduct (TMPA). This adduct was then epoxidized using epichlorohydrin and KOH as catalyst to synthesize an epoxy resin (TMPAE), which was further esterified using methacrylic acid in the presence of triphenyl phosphine as catalyst and hydroquinone as inhibitor to produce bio-based multifunctional vinyl ester resin (VTMPAE). This article also reports the synthesis of lignin model compounds i.e. methacrylated eugenol (ME) and methacrylated guaiacol (MG) as bio-based reactive monomers for vinyl ester resins. The chemical structures of all synthesized products were analyzed using FTIR, (HNMR)-H-1 and C-13 NMR spectroscopic techniques. The thermal and mechanical properties of the samples were evaluated using Differential Scanning Calorimetry (DSC), Thermogravimetric Analyzer (TGA) and Universal Testing Machine (UTM), respectively. Chemical and corrosion resistance of the above cured VTMPAE samples coated on steel panels were also evaluated as a function of % weight loss by immersing the VTMPAE samples in 1 M HCl, 1 M NaOH, and 1 M NaCl solutions for 90 days. The morphological changes that appear upon such an exposure were also studied with the help of Scanning electron microscopy (SEM).