Tung Oil-Based Modifier Toughening Epoxy Resin by Sacrificial Bonds

Sacrificial bonds are critical for the excellent toughness of many natural materials. Herein, to toughen epoxy resin, a renewable toughener (TAA) was prepared by incorporating cyano groups into tung oil, which could form sacrificial bonds by the dipole–dipole interaction and hydrogen bonds. After different contents of TAA were added into diglycidyl ether of bisphenol A, modified epoxy resins were cured by polyetherdiamine. Thermal mechanical properties, morphology, and thermostability of toughened epoxy samples were characterized. Results showed a significant improvement of toughness, and specifically, impact strength, elongation at break, and toughness were able to reach 76.7 kJ·m–2, 25.0%, and 7.6 MJ·m–3, respectively (neat epoxy resin: 21.1 kJ·m–2, 5.7%, and 3.1 MJ·m–3). Besides, by contrast with two other tougheners, which were uneasy to form sacrificial bonds, results indicated sacrificial bonds were critical in the toughening process. Also the toughening effect of TAA is better than that of many commercial tougheners, which reflects its broad potential application.