Synthesis and curing properties of castor oil‐based triglycidyl ether epoxy resin

Three epoxy resins castor oil glycidyl ether (COGE), epoxidized castor oil glycidyl ether (ECOGE) and hydrogenated castor oil glycidyl ether (HCOGE) have been synthesized based on castor oil through a mild epoxidation reaction. The research on curing performance shows that the modified products could improve the toughness of traditional epoxy resins remarkably. Moreover, when adding a small amount of products into traditional epoxy resin E‐51, the mechanical properties of the cured products were also significantly improved. Specifically, by blending ECOGE into E‐51 at a ratio of 5%, the tensile strength, elongation at break, and impact resistance of the cured product were improved by 27.5%, 33.9%, and 39.7%, respectively, from 64.03 MPa, 3.15% and 11.37 MPa to 81.61 MPa, 4.4%, and 15.22 MPa. DMA illustrated that after incorporating, the crosslinking density of the cured product increase, but the glass transition temperatures were reduced by more than 20°C compared with E‐51. SEM showed that COGE and ECOGE caused the cured products to exhibit tough fracture. TGA explained that the initial decomposition temperatures of the mixed systems reduced, but the high temperature resistance of the cured products improved. The design strategy based on castor oil highlights a sustainable avenue for preparing cost‐effective and high‐efficiency epoxy resins.