The Preparation And Study Of Properties Of RGO/CNTs Aerogel-cotton Composite Fabric With Electromagentic Shielidng Function

With the rapid development of 5G communication technology,people's life and the industrial working efficiency were greatly improved by the advanced electromagnetic information technology.However,some negative efforts were also caused by the excessive electromagnetic radiation,such as the damage to human's body health,the disturbance of other electronic equipment and the electromagnetic information leakage,therefore,the research related to the electromagnetic interference shielding material has become the hotspot.In recent years,flexible electronic technology has been continuously improved,including flexible display screen,electronic skin,etc.,thus the preparation of a flexible electromagnetic shielding material has a high practical significance.At present,the most common electromagnetic shielding fabrics in the market are mainly metal-based fabrics,such as metal-fiber mixed fabrics and metal-coated fabrics.Although metal materials could play the role of electromagnetic shielding because of the excellent conductive property,but the application of metal materials is limited due to the shortcomings,including high density,poor chemical stability,stiffness,processing difficulties.With the continuous progress of nanotechnology,there are more and more kinds of nanomaterials were prepared,among which carbon nanotubes(CNTs),graphene and other nanomaterials have become the research hotspot in the materials field for their excellent mechanical,optical and electrical properties.Carbon nanotubes and graphene could be applied to electromagnetic shielding field because of their excellent electrical conductivity.Nevertheless,there is still some disadvantages of nano-carbon materials such as high cost and easy agglomeration.In this research,a porous 3 dimensional aerogel was construct by graphene and carbon nanotubes,and it will be connected with the cotton fabric by coating and fitting with the help of waterborne polyurethane(WPU).The composite fabrics mainly depending on the graphene and carbon nanotubes as functional materials,the WPU plays a role of the binder between the aerogel and cotton fabric,as well as the filling agent and protective layer of aerogel.The cotton fabric is used as a flexible matrix of the composite.The dispersion problems faced by nanomaterials was solved by the porous network structure of graphene/CNTs aerogels,the low density of 3D aerogel was also helpful to decrease the preparation cost of the composite fabric.At the same time,the porous structure is very suitable for dielectric loss of electromagnetic waves.In the preparation of coated composite fabrics,hydrogels with favorable plasticity was coated on the cotton fabric surface,this method is not only facile to operate but also will not be limited by the hydrogel size,so the coated composite fabric is convenient for the preparation in a large-scale.Compared to the coated composite fabric,the fitting aerogel composite fabric has a more complete aerogel porous network structure,and the merit of aerogel could be expressed more obviously.Therefore,the electromagnetic shielding property was further improved by fitting aerogel composite fabric.Through the experimental results,it can be found that(1)The addition of CNTs will decrease the pore size of aerogel,and the certain amount of CNTs is helpful to enhance the electromagnetic shielding property.However,the excessive amount of CNTs has a negative effect on the connection and construction of graphene aerogel.The experimental results show that the optimal weight ratio of graphene to carbon nanotubes is 7:3,and the electromagnetic shielding effectiveness of graphene/CNTs aerogel achieved 40 dB in X-band.(2)The electromagnetic shielding effect of the coated aerogel composite fabric improved with the increase amount of graphene/CNTs hydrogel,and the variation tends to be saturated at 25 mL,the shielding value exceeds 25 dB in the range of X-band.With the increase of WPU content,the fabric tensile strength and bursting strength enhanced significantly,but the tearing strength decreased due to the decline of the fabric deformability.The flexibility and air permeability of the fabric also drop down with the increase of the amount of polyurethane.When the amount of polyurethane exceeds 15 mL,the binding fastness between the hydrogel and the fabric can be basically guaranteed.(3)The electromagnetic shielding value of all the fitting aerogel composite fabric exceed the civil standard of 20 dB,especially,the fabric with 275 mg aerogel obtained a favorable electromagnetic shielding effectiveness result of 33 dB.The variation trend of various properties of fitting aerogel composite fabrics is similar to that of coated aerogel composite fabrics,but the mechanical strength of the fabric is further improved by the multi-layer structure of aerogel layer and fabric.The binding fastness of aerogel layer to fabric could be guaranteed when the WPU amount reached 25 mL.