Study On The Microwave Absorption Behavior Of Graphene /Epoxy Resin Composite

With the rapid development of high-tech and extensive use of a variety of electronic devices in daily life,electromagnetic radiation pollution has been widespread in living environment.Therefore,the attenuation and absorption of electromagnetic waves have aroused crucial concern.Additionally,in military,the interference of electromagnetic waves can have a huge impact on national defense equipment,for instance,these interfere the satellite positioning system and military medical equipment.Therefore,regarding to people’s livelihood or national defense,the preparation of an efficient electromagnetic waves absorbing material is the key solution of aforementioned problems.The absorbing materials are commonly used in absorbing agents such as magnetic particles,ceramics and conductive polymers.Although,these have a certain absorbing effect,still these have some shortcomings like the specific gravity and poor temperature stability,which affect the performance of fabricated devices.The ceramic has a greater density which makes the fabric material components heavier,thus limits the device applications.The conductive polymers which are the type of electrical loss,face the challenges of reducing the thickness of coating and broadening the wavelength band range.Consequently,these materials did not meet the requirements of the absorption of materials which are "light,thin,wide and strong".Therefore,to explore a new type of composite coating absorbing material remains promising.Graphene,as a new type of material has excellent physical properties,such as high conductivity,high dielectric constant,light weight,large size and good mechanical properties.It is expected to become the first choice of new absorbing material filler.Therefore,the preparation methods of three kinds of graphene include graphene powder,graphene paste and graphene cake epoxy particles were studied and the influence of various experimental parameters on the morphology,quality and dispersion stability of the three kinds of graphene was investigated.Also,the threeforms of graphene were combined with epoxy resin during which the preparation method was modified and experimental conditions were optimized to form a new type of porous absorbing material.The effects of different graphene contents on the electromagnetic properties and the absorbing properties of the composite material were investigated.The principle of impedance matching is used to explain the effects of graphene contents on absorbing properties of the composite material.By comparing the reflection loss of the graphene/epoxy resin composite material with different graphene morphologies,the maximum reflection loss of the three composite absorbing materials and the applicable frequency range of the bandwidth of-10 dB are obtained.The reflection loss of the new porous absorbing material formed by the combination of three kinds of graphene and epoxy resin,increases with the increase of graphene contents up to a certain range.After that,it will decline which is due to the impedance of the phenomenon of matching.The other three forms of graphene and epoxy composite materials have their own scope and characteristics:(1)Graphene powder/epoxy resin composite material as a basic research object in the graphene contents of 6 wt %;the sample thickness is about 2 mm,the frequency is10.60 GHz the maximum reflection loss is-23.17 dB and the bandwidth below-10 dB is 3 GHz(9.27-12.27 GHz).(2)Based on graphene powder,the study of graphene paste/epoxy resin composite absorbing material has the best maximum reflection loss among the three types of absorbing materials.The maximum value of the reflection loss is-32.52 dB at graphene contents of 7 wt %;a sample with thickness of about 2mm owns a frequency of 8.00 GHz.(3)Graphene cake epoxy particles/epoxy resin composite material is the third kind of absorbing material with best bandwidth below-10 dB;the bandwidth below-10 dB reach 3.14 GHz(12.90 to 16.04 GHz)when the graphene contents are 3 wt % and the sample thickness is about 2 mm.Therefore,the above three kinds of absorbing materials have their own high absorption and broadband advantages.The study of the graphene based absorbing materials also provides a theoretical basis to further explore the new electromagnetic waves absorbing materials with "light,thin,wide,strong" to lay a solid foundation for thefuture experimentation.