Study On The Recyclability And Shape Memory Property Of Epoxy Resin Based On Ester Bond

With the extensive application of carbon fiber reinforced polymer composites(CFRP)in various fields,its recycling has received wide concerns.The current recycling of CFRP mostly recovers fiber materials with higher value and discards the resin matrix.With the development of material technology and the rigorous requirements of environmental protection,it is imperative to design a green recyclable thermosetting resin matrix.It is of great significance for the resource recycling and environmental protection to realize the full life cycle of CFRP.Based on exchangeable ester bonds,this article systematically studied two classical systems—bisphenol A epoxy/fatty acid system and bisphenol A epoxy/anhydride system under the influence of many factors such as temperature,pressure and solvent.The recycling properties and corresponding chemical mechanism and shape memory behaviors provide a viable scientific approach for achieving 100%recycling and full life cycle utilization of CFRP.The main work is as follows:1.The bisphenol A epoxy/fatty acid system was designed based on the exchangeable ester bond.The influence of zinc salt catalyst on the resin system was systematically studied,and the recycling performance and shape memory behavior were also investigated.Studies have shown that the DSC curing exothermic peak of the epoxy resin decreases,and the tensile properties and the glass transition temperature(Tg)rises,as the content of zinc salt catalyst increases.The bisphenol A epoxy/fatty acid system can be recycled at 180 ? heat and 10 MPa pressure,self-repaired and bonded at 180 ?,and solvent recovered in hydroxyl-rich glycol solvent—ethylene glycol(EG).The mechanism of recycling and self-repairing is:the molecular chain moves above the Tg,and with the exist of the catalyst,the terminal hydroxyl group of the molecular chain contacts with the ester bond which is already formed in the molecular chain to form an unstable intermediate state,thereby forming a new terminal hydroxyl group and a new ester bond.At the same time,the research also found that the bisphenol A epoxy/fatty acid system can achieve shape memory performance at 70 ? based on the stress relaxation behavior at high temperature,and has a good shape recovery rate.2.The bisphenol A epoxy/anhydride system was also designed based on the exchangeable ester bond.The influence of the zinc salt catalyst on the resin system was systematically studied,and the recycling performance and shape memory were investigated.Studies have shown that as the zinc salt catalyst content increases,the DSC curing exothermic peak of the epoxy resin decreases,and the tensile properties and Tg temperature show an upward trend.Based on the same dynamic ester bond mechanism,the possibility of bisphenol A/anhydride epoxy resin system's hot-press recycling was explored.At the same time,the research also found that bisphenol A epoxy/anhydride system exhibited shape memory performance at 100 ? deriving from the stress relaxation behavior at high temperature,as well as a good shape fixation rate.