Preparation Of Microwave Absorbing Film With Carbon Nano-tubes Using Layer-by-Layer Assembly

With the rapid development of electronic devices and communications technology, a new kind of pollution called electromagnetic interference(EMI) cause people’s concern.Some studies have been done on electromagnetic interference shielding and microwave absorbing materials which would provide a protection against the electromagnetic pollution.Carbon nanotubes (CNTs) have show exceptional waveabsoring properties.But the poor dispersion in materials limits its comprehensive applications This thesis use carbonnanotubes as microwave absorbing factor and prepare microwave absorbing film using layer by layer Assembly which improve the dispersion of CNTs and make the precise regulation of film structure become possiable,and this thesis will make a foundation for the further adjustment of film structure.The CNTs solution and Poly(allylamine hydrochloride)(PAH) solution with salt had been used to prepare the CNTs/PAH film The procedure of film preparation had been studied.And SEM\FTIR\XPS\TGA had been used to characterize the structure of CNTs/PAH film Finally,we prepared the CNTs/PAH film on cotton fabric to made it one kind of microwave absorbing material.And the perfomance of the film had been tested.Elemental analysis results had showed the yield of CNTs and PAH in the film.Morphology analysis showed CNTs.tiled on the base and PAH worked as a connection factor to link the carbon nano-tubes With the growth of the layers on the film, the formation of the bridges between adjacent fibers occured, a whole film covering the surface of cotton fabric were formed finally.The surface resistivity of samples decreased with the number growth of CNTS/PAH bilayers.And the surface resistivity decreased when the concentration of CNTS solution became larger.The study got a samllest surface resistivity (6.81KΩ/sq) when the concentration of the CNTS was2.5mg/ml and the number of bilayers was10.The EMI shielding effectiveness results showed that the more bilayers of the film,the better the shielding effectiveness becomed.The thesis got best shielding effectiveness value of2.4-3.5dB when the thickness of film was150-225nm.