Preparation And Properties Of Self-healing Epoxy Elastic Polymer

Epoxy polymers have excellent mechanical properties,chemical stability,high and low temperature resistance,as well as easy processing and low cost,and are widely used in preparing adhesives,coatings,composite materials and other materials.However,epoxy polymer has a three-dimensional network structure formed by a covalent bond.The crosslink density is high and the texture is hard.When external stress is applied,damage is easily generated,and many microcracks may formed inside the structure,which may be harmful to the mechanical properties and the service lifetime of the polymer.Therefore,there is a realistic need to repair cracks generated in the epoxy polymer collective.The problem of self-healing of epoxy polymer can be effectively solved by placing a reversible covalent bond in the epoxy polymer matrix.But the currently prepared epoxy self-healing polymers containing reversible covalent bonds have some shortcomings,such as low mechanical properties and poor flexibility,which greatly limit its application range,especially in the flexible circuit board seals and stress-sensitive applications.Therefore,it is necessary to prepare an epoxy elastomer polymer having high mechanical strength,high elongation at break,and capable of self-healing.The epoxy elastic polymer with self-healing function was prepared by mixing FDB and OCG,and then reacting with polyetheramine D-230,the repeated healing performance and self-healing mechanism of elastomeric epoxy polymer materials were studied.The results show that the elastic epoxy polymer containing furan-maleimide reversible covalent bond with thermoreversibility,and a series epoxy elastic polymers with different crosslinking densities,glass transition temperatures,different tensile strengthes and elongations can be prepared by changing the OCG/FDB molar ratio.With increasing the OCG/FDB molar ratio,the glass transition temperature will decrease,the tensile strength and elongation at break will increase first and then decrease,which has a optimal molar ratio of approximately OCG/FDB=1.5 with amaximum tensile strength of 9.57 MPa and an elongation at break of 316 %.The optical microscopic observation and tensile shear tests show that the epoxy elastic polymers possess repeated damage healing performance and can be disassembled easily.The healing rate increases with the increase of the content of OCG and the repair temperature.In order to find more convenient methods to realise the damage healing for the above-mentioned epoxy elastic polymer,nano-graphene sheets(GNS)are dispersed in the mixture of furan-maleimide glycidyl ether and octanediol glycidyl ether and then curing by polyetheramine D-230 to form an epoxy-elastic polymer with infrared healing function.The healing performance and its mechanism of the graphene/epoxy elastic polymer material were studied.The results show that the prepared GNS/epoxy elastic polymer has repeated reversibility of healing under infrared heating.A series epoxy resins with different glass transition temperature,tensile strength and elongation can be prepared through the modification of the mass ratio of nano graphene sheets to epoxy.The glass transition temperature increases with the increasing of the GNS quantity in the mixture.To the contrary,the tensile strength and elongation at break will decrease with the increase of the GNS added in the composite.The optical microscopy and the heating experiments show that the GNS/epoxy elastic polymer has repeated damage healing ability and disassembility under infrared heating.The healing rate will decrease,and the healing time will first increase and then decrease with increasing the quantity ratio of GNS to epoxy resin.