Study On The Thermal Stability Of Epoxy-amine Self-healing System And Its Self-healing Performance In Medium And High Temperature Curing Epoxy Resin

Anhydride-cured epoxy resin has excellent mechanical properties,electrical properties,water resistance,heat resistance,and radiation resistance.It is widely used in high-grade fields such as electronic information field,navigation and aerospace.However,as a thermosetting polymer material,its poor toughness makes it susceptible to external impacts to produce microcracks and cause further damage.Adding microcapsules containing repair fluid to epoxy resin can not only endow it with self-repairing function,but also improve its toughness.Since the use of acid anhydride to cure epoxy resin requires a higher curing temperature,higher requirements are put forward for the thermal stability of the microcapsule-type self-healing system and bring challenges to a certain extent.In this paper,based on the microencapsulated epoxy-amine chemical self-repair system with excellent comprehensive performance,the medium and high temperature thermal stability of the system and the influence of the heat treatment temperature on its self-repair performance are studied,and the self-repairing system with better medium and high temperature thermal stability is researched and developed.The main research contents of this paper are as follows:(1)The physical and chemical properties of four polyamine with different typical structures(tetraethylenepentamine for TEPA,metaxylylenediamine for XDA,polyether polyamine T403 and T3000)are systematically studied in this paper.Using T-junction microfluidic-rapid interfacial polymerization method and electrostatic spray-rapid interfacial polymerization method,the feasibility of microencapsulation of these four amine curing agents was verified,and the physicochemical properties and microencapsulation of amine curing agents were explored.The process parameters affect the microencapsulation process and the quality of the final microcapsules,and on this basis,the performance of the microcapsules is adjusted.The research results show that the physicochemical properties of the polyamines have a significant impact on the microencapsulation process and the final microcapsule structure properties.By changing the reaction solution,reaction conditions and adjusting the core liquid composition of the amine curing agent,we can realize the microencapsulation of the polyamine with different physicochemical properties,and prepare high-quality microcapsules containing polyamines.(2)According to the curing temperature requirements of the acid anhydride curing agent curing epoxy resin,this paper further studies the thermal stability of selected microcapsule core material,microcapsule carrier outside and in the resin matrix,its influence on the self-healing performance was also studied.Based on the comprehensive requirements for high thermal stability and high repair performance,The self-healing system have been analyzed and selected for medium and high temperature curing epoxy resin.Experimental results show that the main repair agents selected in this research,including Polyetherimide JEFFAMINE T403 and epoxy monomer bisphenol F diglycidyl ether(BFDGE),and microcapsules based on these two repair agents have good thermal stability.The self-healing materials based on these dual component microcapsules still maintained self-healing efficiency of nearly 60 % after the post-curing treatment of 100 ? 3 h+130 ? 2 h+170 ? 3 h,which proves that the self-healing system based on encapsulated epoxy-amine still has application potential in epoxy resin cured at medium and high temperature to a certain extent.