Study on mechanical properties and curing properties of shear‐thickening gel toughened epoxy resin

Abstract

The shear‐thickening gel (STG) is introduced as a toughening agent into the epoxy resin (EP) to improve the toughness and impact resistance of the EP without significantly increasing its viscosity. By utilizing the unique BO dynamic bonds present in STG, the EP/STG composite exhibits remarkable toughness at low strain rates due to the gradual disentanglement of molecular chains. Conversely, at high strain rates, the disentanglement of molecular chains is hindered, resulting in a pronounced impact hardening effect and overall superior impact resistance. Our findings reveal that when STG is added at a concentration of 15%, the EP/STG composite material attains its peak mechanical performance. Specifically, it demonstrates a tensile strength of 31.8 MPa and a modulus of elasticity of 550.6 MPa. Furthermore, compared to pure EP, the EP/STG composite experiences an increase in elongation at break and impact strength by 40% and 8.1%, respectively. Additionally, the introduction of hydroxyl and B atoms in STG promotes the ring‐opening reaction of epoxy groups during the curing process of the EP, thus accelerating the curing reaction rate. These insights provide a solid theoretical foundation for optimizing the performance of EPs in engineering applications.Highlights The STG was actively utilized to enhance the toughness of EP. The modified EP system exhibits significant improvements in toughness and impact resistance without a notable increase in viscosity. The promotional effect of STG on the curing of EP systems was revealed through curing kinetics analysis and rheological analysis.