Study On Preparation And Self-healing Properties Of EVA-Epoxy Resin Adhesive

Thermosetting resin has the advantages of easy processing and molding,high strength/modulus,good bonding performance,etc.As a structural adhesive,it should be widely used to strengthen and repair civil engineering structures.As a thermosetting resin,epoxy resin has poor fracture toughness,which can easily lead to brittle failure and fatigue damage and affect the service performance and life of the structure.The development of thermosetting epoxy resin-based adhesives with self-healing properties to achieve automatic repair of internal damage to adhesives can improve the service life of materials and structures,and is of great significance.This paper develops a new type of epoxy resin-based adhesive that can be self-healing after treatment at a lower temperature by adding a thermoplastic ethylene-vinyl acetate copolymer(EVA)that can be melted at low temperature into the epoxy resin adhesive.Study the preparation method and self-healing mechanism of this kind of self-healing adhesive,and establish self-healing performance evaluation method.The main research contents and research results of this article are as follows:Preparation method of EVA-epoxy resin self-healing adhesive: By controlling the mixing and adding process,EVA-epoxy resin self-healing adhesive with uniform component dispersion and stable performance is prepared.The research results show that the addition of fumed silica thickener can solve the delamination problem of EVA and epoxy resin after mixing.Through the optimization of the preparation process(such as mixing temperature and speed),a ring containing uniformly dispersed EVA components is prepared Oxygen resin adhesive.Thermal and mechanical properties of EVA-epoxy resin self-healing adhesive: Three kinds of EVA-epoxy resin self-healing adhesives with different EVA contents were prepared,and the effect of EVA content on the properties of the adhesive was studied.The research results show that,with the increase of EVA content,the flexural strength of the adhesive decreases linearly with no significant change in glass transition temperature.The self-healing performance evaluation method of EVA-epoxy adhesive is proposed: firstly,a blade is used to create a natural crack at the center edge of the adhesive plate,and then the temperature is repaired,and the adhesive is evaluated according to the remaining bending strength of the adhesive sample before and after the temperature repair treatment Self-healing properties.The research results show that this method can effectively evaluate the self-healing properties of self-healing adhesives.Self-healing properties of EVA-epoxy resin adhesive: Three kinds of self-healing adhesives with different EVA content were prepared,and the thermo-mechanical properties of the adhesive were systematically studied.The research results show that with the increase of EVA content,the self-healing performance of the adhesive decreases.The self-healing efficiency of the adhesive with 5 wt.% EVA content is the highest.The self-healing mechanism of the self-healing adhesive is EVA after heating.Melt penetrates into the crack tip to passivate it.