Construction of multiple sacrificial bonds between epoxy resin and tung oil-based modifier towards mechanical performance enhancement

The development of plant oil-based modifiers that significantly improve the toughness of diglycidyl ether of bisphenol A (DGEBA) while exerting minimal adverse effects on their strength and modulus poses a critical challenge. Biological materials such as nacre, bones, spider silk, and tendons are characterized by the presence of sacrificial bonds, which contribute significantly to their exceptional strength and remarkable toughness. In this study, a tung oil-based epoxy terminated polyurethane (TETPU) was synthesized, drawing inspiration from biological materials. The significant enhancement in toughness was achieved while preserving exceptional mechanical strength by integrating sacrificial bonds through the formation of hydrogen bonds and π-π interactions within the epoxy resin network. The incorporation of 30 wt% TETPU resulted in a 111.7% increase in elongation at break, a 40.29% increase in toughness, and a 90.59% increase in impact strength compared to the neat DGEBA. Additionally, the tensile and flexural strength underwent a decrease of 16.36% and 18.80%, respectively. The exceptional performance can be attributed to the formation of multiple sacrificial bonds between TETPU and epoxy network. The study presents a direct and effective approach for producing plant oil-based epoxy modifiers, resulting in a substantial enhancement in toughness with minimal effects on strength and modulus.