Synthesis of Castor Oil-Derived Decanediamide as a Novel Flexible Asphalt-Modified Epoxy Resin Curing Agent

Castor oil-derived decanediamide, as a novel flexible epoxy curing agent, was synthesized by esterization with methanol and ammonolysis with ammonia. The chemical structure and thermal properties of this novel curing agent were confirmed by Fourier transform infrared spectroscopy (FT-IR), 1 H nuclear magnetic resonance ( 1 H NMR) analysis, differential scanning calorimeter (DSC), and thermogravimetric analysis (TGA). The tensile strength, impact strength, dynamic mechanical properties, and thermal stability of cured epoxy resin were investigated by tensile tests,dynamic mechanical analysis (DMA), and TGA, respectively. The results showed that the prepared decanediamide had a high yield of 85.4%, and the epoxy resin cured by the decanediamide revealed a slight decrease in the mechanical properties and thermal stability, and a longer pot life at high temperature compared with that of a conventional epoxy curing agent. Asphalt as a toughening agent was added into this system, in order to improve the poor brittle resistance of pure epoxy resin, which proved to have good compatibility with this system and improve the brittle resistance effectively. Thus, the decanediamide has a great potential to replace some of current petroleum-based compounds in the synthesis of epoxy curing agents.