Synthesis of biobased epoxy and curing agents using rosin and the study of cure reactions

Rosin is an abundantly available natural product. Rosin is a mixture of acidic (ca. 90%) and neutral (ca. 10%) compounds. The characteristic fused ring structure of rosin acids is analogous to that of some aromatic compounds in rigidity, and makes rosin and its derivatives potential substitutes for those aromatic compounds in polymers. In this study, the synthesis of biobased epoxy and curing agent using rosin and the cure reaction were investigated. Abietyl glycidyl ether and methyl maleopimarate were synthesized from one of the rosin acids. Abietyl glycidyl ether was used as a model compound representing rosin-based epoxies, while methyl maleopimarate was used as a model compound representing rosin-based anhydride curing agents. The synthesis methods of the model compounds were examined and the chemical structures were confirmed by 1H NMR, 13C NMR, FT-IR and ESI-MS. Curing of abietyl glycidyl ether with aniline and curing of methyl maleopimarate with phenyl glycidyl ether were investigated separately. Nonisothermal curing of the model systems was studied by DSC, and the cured products were characterized by 1H NMR.