Study On Treatment Of Carbon Nanotubes And Electrical Conductivity And Radar Absorbing Properties Of Its Composite Materials

Carbon nanotubes(CNTs) have attracted much attention for their many promising properties and potential applications.CNTs have special structure and specific electromagnetic properties,such as high aspect ratio,high surface area,small size et al,so they own potential applications in microwave absorbing filed.In this dissertation,dispersibility of multi walled carbon nanotubes(MWNTs) was enhanced by purification,KOH-activation and Fenton's reagents treatment,surface modification and electroless cobalt plating.At the same time,the application of MWNTs with Co coating in the field of the compound microwave absorbing material was studied.Firstly,the treatment of the MWNTs was studied.After purification pretreatment by dilute HNO₃ under ultrasonic treatment,MWNTs were activated with KOH and NaOH,then they were treated with Fenton's reagents.By the result of TEM and SEM,it was found that the amorphous carbon,catalyzer and other impurities on the carbon nanotubes surface were removed and the purity of the carbon nanotubes was raised obviously.The KOH and NaOH activation and Fenton's reagents-treatment make carbon nanotubes open,short cutting and enhance its dispersibility.Secondly,the cobalt plating on the surface of MWNTs was analyzed.MWNTs were coated with cobalt through the method of electroless plating.The coating was consecutive and homogeneous.In addition,the mechanism of sensitization,activation and chemistry cobalt-plating were investigated in this dissertation.Finally,the microwave absorbing properties of three kinds(raw MWNTs, NaOH-activated MWNTs and the Co-coated MWNTs) of MWNTs/epoxy composites were measured.It has been found that the maximum absorbing peak of raw MWNT/epoxy composite appeared at C frequency area,and the maximum absorbing peak of Co-coated MWNTs/epoxy composite and NaOH-activated MWNTs/epoxy composite have been shifted to X and Ku frequency area,respectively,which indicates that by different treatment of MWNTs,the absorbing peak of an composite can be well adjusted.