Terahertz Spectral Characteristic Of Typical Polymer Dielectric

With the development of science,terahertz(THz)technology has become mature gradually.People have paid more attention to THz due to its superiority of nondestructive testing.The absorbance and refractive index of sample can be acquired by the measurement of THz time-domain.The composition and structural information of substance can also be researched by analyzing characteristic absorption.Polymer dielectric is widely used in electrical engineering area because of its excellent electrical properties.Spectrum detection plays an important role in studying the internal motion and micro-acting-force.Due to its special frequency band,THz time-domain spectroscopy can analyze the vibration and rotation of macromolecule effectively,which become a forceful supplement of other spectrum technology.In this paper,by using the THz timedomain spectroscopy,we make a fundamental study about kinds of typical polymer dielectric.Firstly,the composition and working principle of THz time-domain system are introduced.THz wave interacting with macromolecule is analyzed further.Secondly,the test method about THz time-domain is discussed.By testing water's influence in THz measurement,we find out that water content do have an influence on veracity.So,experimental environment and sample must be desiccative.Finally,optical parameter is deduced.We test various typical polymer and nano-composites on this basis.Experimental result shows that the absorbance and refractive index of PI are higher than LDPE.The Si O2/LDPE nano composite dielectric of 1wt% show a reduction about THz wave and the refractive index is higher than before.The Mg O/LDPE nano composite dielectric and the Al2O3/LDPE nano composite dielectric with the doping of same proportion also appeared the same results.Besides,the absorption of THz wave is increased about LDPE doped 1wt%conductive black(CB).The CB/LDPE composite dielectric of 20wt% is more obvious about absorbing THz wave and enlarged significantly in refractive index.The absorbance and refractive index of LDPE injected space charge are also increased.According to the analysis about spectral information,we can provide rationale and experimental data for spectral characteristic tested by THz timedomain spectroscopy.