Investigation On Self-healing And Shape Memory Properties Of Polyurethane Modified Epoxy Resin Based Vitrimer

Shape memory polymer is a widely used functional polymer material.Thermoset shape memory materials have excellent mechanical properties and chemical stability,and have made outstanding contributions in the aerospace field.Self-repairing performance plays an important role in thermosetting shape memory materials.It can autonomously repair the deformation damage of shape memory materials,increase the service life of materials,and reduce the loss of materials.In this article with isophorone diisocyanate and polyethylene glycol polyurethane prepolymer was prepared to toughen epoxy resin E51,with which together with methyltetrahydrophthalic anhydride,and stannous octoate catalyzes,epoxy shape Memory material with self-repairing properties was prepared..The thermodynamic properties such as glass transition temperature of the epoxy materials and the mechanical properties such as flexural strength and toughness were studied.The stress relaxation behavior of materials was studied by rheological experiments.The repair performance of the material was studied by its thermal welding performance,the bending strength of the repaired material,and the repair of macroscopic scratches.By studying the relationship between the deformation recovery time and the angle of the material,the shape memory performance of the material was studied.Research showed that the addition of polyurethane prepolymer changed the chain structure of epoxy resin,resulting in the increase of the bending strength the toughness of epoxy resin.Adding a catalyst during curing accelerated the ring-opening rate of epoxy and methyltetrahydrophthalic anhydride,which accelerated the curing rate of epoxy resin and increased the curing degree of epoxy resin.The vitreous epoxy resin was a rearrangement of the topological network realized by the transesterification reaction of hydroxyester and urethane in the system.The stress relaxation behavior of vitreous epoxy resin system was composed of the two kinds of relaxation.One was caused by the small unit in the crosslinked polymer in response to external force,and the other was caused by the transesterification behavior in the system.Both catalyst and temperature affected the relaxation time caused by transesterification.The activation energy of the transesterification reaction calculated from the relaxation time was less than that of the elastic glass epoxy resin,but the performance was much better than that of pure epoxy resin.The material has a good repair effect on the strength damage and macro scratches in the system.The shape memory performance of the material is good,but the deformation cannot be recovered infinitely.