Enhanced dynamic network restructuring of recyclable dual-cured epoxy resins
摘要
1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) as an organic base with high catalytic efficiency and excellent compatibility with epoxy resin (EP), is widely used as a catalyst for ester exchange reactions to enhance the dynamic restructuring of the network. However, it will be involved in the curing process, change the cross-linked structure, and affect the properties of the material. In this paper, the effect of TBD on the dynamic, physicochemical, and dielectric properties of dual-cured epoxy resin was investigated, the method of TBD to enhance the dynamic reorganization of dual-cured epoxy resin network was proposed, the mechanical and dielectric properties of TBD composite dual-cured epoxy resin were studied, and the synergistic relationship between TBD and pressure of dual-cured epoxy resin explored. It shows that TBD enhanced the viscoelastic behavior, shortened the stress relaxation time, lowered the topological freezing transition temperature (Tv), and improved the dynamic network reorganization efficiency of dual-cured epoxy resin, but TBD reduced its thermal stability and affected the mechanical and dielectric properties. TBD enhanced the network reorganization ability of recycled dual-cured epoxy resin, improved the interfacial healing effect, and enhanced the mechanical and dielectric properties of recycled dual-cured epoxy resin. However, the enhancement effect of TBD was weakened with the increase of hot-pressing pressure, and the excessive amount of TBD would destroy the network structure, resulting in the decrease of the mechanical and dielectric properties of the recycled dual-cured epoxy resin. The above shows that we have developed a low-energy and high-efficiency network dynamic reconfiguration enhancement method, which is important for guiding the industrial scale-up of thermal pressure recovery.