Rosin-based acid anhydrides as alternatives to petrochemical curing agents

In this paper, two bio-based epoxy curing agents were synthesized using rosin acids. The chemical structures of the rosin derivatives were confirmed in detail by 1H NMR, 13C NMR, FT-IR and ESI-MS. The synthesis methods of the rosin-based curing agents, curing behaviors and properties of the cured epoxy resins were studied. Two commercial curing agents, which have similar functionality and structural resemblance to the rosin-based curing agents, were also used in the study for comparison. Compared with the synthesis of petrochemical curing agents, the synthesis of rosin-based curing agents was simpler and more environmentally friendly, and has less strict requirements on reactors and catalysts. Non-isothermal curing of a commercial liquid epoxy was studied using differential scanning calorimetry (DSC). The thermal mechanical properties and thermal stability of the cured epoxy resins were evaluated using dynamic mechanical analysis (DMA) and thermogravimetric analysis (TGA), respectively. Results showed that the curing behaviors of the rosin-based curing agents were similar to those of the commercial curing agents. The epoxies cured by rosin-based curing agents also demonstrated similar thermal mechanical properties and thermal stability to the epoxies cured by commercial curing agent analogs.