Epoxy Monomers Derived from Tung Oil Fatty Acids and Its Regulable Thermosets Cured in Two Synergistic Ways

A novel biobased epoxy monomer with conjugated double bonds, glycidyl ester of eleostearic acid (GEEA) was synthesized from tung oil fatty acids and characterized by H-1 and C-13 NMR. Differential scanning calorimeter analysis (DSC) and Fourier transform infrared spectroscopy (FT-IR) were utilized to investigate the curing process of GEEA with dienophiles and anhydrides. DSC indicated that GEEA could cross-link with both dienophiles and anhydrides through Diels-Alder reaction and epoxy/anhydride ring-opening reaction. Furthermore, Diels-Alder cross-link was much more active than the ring-opening of epoxy and anhydride in the curing process. FT-IR also revealed that GEEA successively reacted with dienophiles and anhydrides in both cross-linking methods. Dynamic mechanical analysis and mechanical tensile testing were used to study the thermal and mechanical properties of GEEA cured by maleic anhydride, nadic methyl anhydride and 1,1'-(methylenedi-4,1-phenylene)-bismaleimide. Due to the independence between the curing agents, dienophile and anhydride, a series of thermosetting polymers with various properties could be obtained by adjusting the composition of these two curing agents.