Effect of different purification method on electromagnetic propetries of multiwalled carbon nanotubes

Multi-walled carbon nanotubes(MWCNTs) were purified using such five different methods as nitric acid reflux,vitriol reflux,nitration mixture reflux etc.Then these MWCNTs were analyzed by TEM,XRD and FT-IR to study the change of external structure.The complex permittivity and permeability were measured from 2-18GHz by the coaxial method.The effect of different purified methods on complex permittivity and permeability were investigated.The results show that amorphous carbon and catalyst particles on the surface of MWCNTs are wiped off effectively,and such functional groups as carboxyl and hydroxylare introduced.Real and imaginary part of complex permittivity both drop,and complex permeability has no substantial changes.To comprehensively survey of the test results,preferably choosing nitric acid reflux treatment process to purify MWCNTs.