THz time-domain spectroscopic study of polyethylene-carbon black composites

Abstract

Terahertz time-domain spectroscopic technique was applied to investigate the optical properties of polyethylene-carbon black composites in the frequency range of 0.3-2.0 THz as a function of frequency and volume fraction of the carbon black. It is found that the absorption coefficient and the refractive index of the composite increased with increase of carbon black content. At the same carbon black concentration, the absorption coefficient increased and the refractive index decreased with increase of frequency. The experimental measurements were analyzed by using Debye theory of dipole relaxation under the assumption that carbon black particles dispersed in the polyethylene matrix behave like dipoles and contribute mainly to the dielectric loss.