Study On The Preparation And Performance Of Functionalized Graphene Oxide/epoxy Resin Composites

The graphene has extremely excellent mechanical properties,high specific surface area,and good electrical and thermal conductivity,so it has a wide range of applications in the field of resin matrix composites.However,the graphene sheets are extremely easy to aggregate.And due to its reaction inertness and incompatibility with resin matrix,its application in the field of resin matrix composites is limited.The graphene oxide,as a derivative of graphene,has lots of oxygen-containing functional groups,so it has a good compatibility with the resin matrix.And the graphene oxide still retains the graphene's properties,such as high specific surface area and excellent mechanical properties,etc.Therefore the graphene oxide has attracted many attentions in the field of resin matrix composites.The experiment aims to improve the comprehensive properties of epoxy composites by modifying the graphene oxide with different grafting methods.On the one hand,the grafting modification can increase the exfoliation degree of the graphene oxide and improve its dispersion state in the epoxy matrix.On the other hand,different active functional groups at the end of the grafting materials are utilize to react with the resin matrix,which improves the interfacial interaction between the graphene oxide and the resin matrix to enhance the comprehensive properties of epoxy resin.In part one,the graphene oxide is successfully prepared by the modified Hummers method.Then the epoxy resin is grafted on the surface of the graphene oxide by in-situ grafting method.Through the characterization,it is found that the graphene oxide exhibits a wrinkled monolayer dispersion state.The original regular structure of graphene oxide has turned into the loose stacking manner.The corresponding epoxy resin composites are prepared and characterized.It is found that the modified graphene oxide displays a uniform dispersion state,the modified graphene oxide and the epoxy resin have formed a strong interfacial interaction,while the modified graphene oxide can effectively improve the toughness of the epoxy resin.The tensile strength and the elongation at break of the composite material has enhanced by 19%and by 31%respectively compared with that of the pure epoxy resin when the modified graphene oxide loading is 0.25wt%.And when the amount of the modified graphene oxide is0.50wt%,the glass transition temperature has risen by 45°C compared to that of the pure epoxy resin.The thermal stability and water resistance of the composite materials also have been improved.The hyperbranched polysiloxane modified graphene oxide is studied in part two.After the characterization,it is found that the hyperbranched modified graphene oxide has a good exfoliation degree.The modified graphene oxide is wrapped by resin.The corresponding epoxy composites are prepared by the solvent mixing.When 0.10wt%modified graphene oxide is added,the tensile strength and the elongation at break has enhanced by 59%and by 186%respectively.The glass transition temperature of the composite material has risen by 35?compared with that of the pure resin when the adding amount is 0.20wt%.The thermal stability of the material has been significantly improved.The amino at the end of hyperbranched polysiloxane can participates the curing reaction of the resin matrix,which makes the interfacial interaction between the resin matrix and the modified graphene oxide be stronger,therefore the water absorption rate has greatly declined when the adding content is low.In part three,the reduced graphene oxide(rGO)is firstly prepared by the chemical methods and then modified with amino-terminated hyperbranched polysiloxane.The silver nanowires(AgNWs)with a higher length to diameter ratio are manufactured by the polyol method,and loaded onto the modified rGO surface.Through the characterization,it is found that the chemical method can effectively eliminate the oxygen-containing groups on the graphene oxide surface.The hybridization of the carbon atoms in the graphene oxide has turned into sp~2 from sp~3 hybridization.The modified rGO disperses uniformly in its corresponding epoxy resin composites,and there is no obvious agglomeration.The glass transition temperature of the composite material has risen by 25°C when the modified rGO is 3wt%.When the loaded modified rGO is 5wt%,the electrical conductivity of the composite material has increased by 11orders of magnitude,and the dielectric constant of the material has increased by 184%compared with that of the pure material.