Novel renewable resource-based UV-curable copolymers derived from myrcene and tung oil: Preparation, characterization and properties

Two novel ultraviolet (UV)-curable vinyl ester resin (VER) monomers derived from myrcene and tung oil were synthesized via Diels-Alder reaction, glycidylation reaction and ring-opening esterification. Their chemical structures were confirmed by Fourier transform-infrared analysis (FIR) and Proton nuclear magnetic resonance (H-1 NMR). Then the two VER monomers were mixed at different weight ratios and cured under UV light. The curing processes were monitored by FTIR analysis. Tensile and flexural properties of the cured resins were also tested. The conversion rate of double bond exceeded 80% within 60s and the final conversion rate was 95%. Tensile and flexural tests indicated that the rigidity-flexibility was balanced in the cured systems when the mixed resins contained 50-70 wt% of myrcene-based VER monomer. Dynamic mechanical analysis demonstrated that the storage modulus and glass transition temperatures of the cured resins increased with the increasing content of myrcene-based VER monomer. The crosslinking density of the cured copolymers also increased with the increasing content of myrcene-based VER monomer. Thermogravimetric analysis (TGA) showed that the main thermal initial decomposition temperatures (TO of the cured copolymers were all above 388 C. All the results demonstrated that comparable balanced properties could be obtained by mixing these two bio-based monomers together. (C) 2014 Elsevier B.V. All rights reserved.