Nondestructive Separation Of Flexible Carbon Nanotube Macrofilms And Electromagnetic Shielding Properties Of Electrodeposited Copper

Our life becomes more and more convenient with the rapid application of electronic devices.In addition,some potential threats also rising.Thereby,shielding materials should be applied for preventing the radiation that generated from the electromagnetic wave.Currently,commercial shielding materials are metals or other composites that filled conductive particles.Due to their high density and unflexibility,it is still unconvenient for application.Carbon nanotubes(CNTs)show a good electromagnetic shielding performance for their special structure.Therefore,they were added into polymer as conductibe filler for shielding electromagnetic waves.However,the shielding effectiveness of the composites is still not high enough due to limited loading of the CNTs.In this study,CNTs macro film(CMF)were used to shield electromagnetic waves.Usually,substrates should be provide for preparation of CMF.Therefore,the substrate and the CMF should be separated first.And free-standing CMF can be obtained.According to the present method,it is difficult to separate CMF from the substrate.In this thesis,separating CMF from their substrate and the electromagnetic shielding properties of the CMF were investigated.The CNTs were prepared by floating catalytic chemical vapor deposition(CVD),and then they were assembled into CMF.The mechanism of separation CMF from printing paper was discussed.Due to effect of ethanol,CNTs is adsorbed on the printing paper.And the physical adsorption was demonstrated.Further,larger surface roughness of printing paper makes separation more easier.It is found that CMF has a smooth surface and good thickness uniformity after checked by XRD,SEM,HR-TEM.Good graphitization structure of the CMF also have been demonstrated,the conductivity changing of the CMF is negligeable when the tensile deformation less than 10 %.And the largest size of the CMF reached about 1880 mm*1000 mm.Cu/CMF composites were obtained through electrodeposition method that Cu particles were deposited on the surface of the CMF.The conductivity of Cu/CMF composite is similar to commercial Cu foil.In addition,the composite maintains light weight and high flexibility.And it can not be broken after folding several times.In the high frequency band,the electromagnetic shielding effectiveness of the composite is higher than as-prepared CMF and CMF that filled with Fe nanoparticle.Compared with asprepared CMF,the average electromagnetic shielding performance of Cu/CMF composite was increased 10.3-25.7 % in the range of 10-18 GHz.The average electromagnetic shielding effectiveness increases 7.5-19 % than CMF that filled Fe nanoparticle in the 9-18 GHz frequency range.At ~15 GHz,the shielding effectiveness of Cu/CMF composite is as high as 53.3 dB.