Study On Interpolymer Interface Welding Behavior Based On Epoxy Vitrimer

Vitrimer with dynamic covalent adaptive network has a wide range of potential applications in reprocessing,self-healing and welding.Research on the interface welding behavior of vitrimer can provide important theoretical and technical support for in-depth understanding of vitrimer bonding,self-healing and other behaviors,and expand practical applications.In this paper,T-type peeling experiment was used to study the interface welding behavior between epoxy vitrimer,epoxy vitrimer/thermoplastic polyurethane,and carbon fiber reinforced epoxy vitrimer composites.The research results are as follows:（1）Research on the welding behavior of epoxy vitrimer interface shows that:With the increase of catalyst dosage from 1 wt.%to 7.5 wt.%,the breaking strength,Young’s modulus and elongation at break of epoxy vitrimer decrease by about 30%.For the sample catalyzed by triphenylphosphine（PPh₃）,the stress relaxation time decreases.The fracture energy of interfacial welding increases from 1725.55 J/m² to 2363.41 J/m².The activation energy（E_a）of transesterification reaction between epoxy vitrimer varies with the type of catalyst.The transesterification reaction rate with low E_a is faster and the fracture energy of interfacial welding is larger.The fracture energy of interfacial welding increases with the increase of welding temperature and time.（2）Research on the welding behavior of epoxy vitrimer/thermoplastic polyurethane interface shows that:The ester group of epoxy vitrimer can transesterize with the carbamate in thermoplastic polyurethane to form a strong welding interface.With the increase of catalyst content,the transesterification reaction rate increases and the interfacial fracture energy increases.Using catalyst with higher catalytic efficiency can also increase the transesterification reaction rate and interfacial fracture energy.Increasing welding temperature and time also increases the fracture energy of interfacial welding.（3）Research on the welding behavior of the interface between carbon fiber reinforced epoxy vitrimer composites shows that:The fracture strength and Young’s modulus of epoxy vitrimer reinforced by carbon fiber are increased by8 times and 10 times respectively.The fracture energy of interfacial welding can be improved by increasing the amount of catalyst,welding temperature and welding time.