STUDY ON DISPERSION CHARACTERISTICS OF EPOXY RESIN NANOCOMPOSITES AT TERAHERTZ RANGE

In this paper, we prepared three kinds of nanocomposites based on epoxy resin. They are epoxy resin/silicon dioxide, epoxy resin/silicon carbide and epoxy resin/zinc oxide, respectively. By employing terahertz time-domain spectroscopy, we investigate their dispersion characteristics at terahertz range. We fitted the results by Lorentz harmonic oscillator model. The obtained optical dielectric constants of EP/SiO₂, EP/SiC and EP/ZnO nanocomposites increase monotonously with the filler content increaseing. The damping coefficients of EP/SiO₂ and EP/SiC nanocomposites increase first and then decrease with the increase of filler content, while that of EP/ZnO nanocomposite decreases monotonously. We speculate that the increase of the damping coefficient result from the restriction of the interfacial region on the molecular chain motion. When the filler content is larger than 5%, the damping coefficient decreases significantly due to the agglomeration of nanoparticles and overlap of interfacial regions. There is no interaction region between the ZnO nanoparticles and epoxy resin, resulting in that the structure of epoxy resin becomes loose with the incorporation of ZnO nanoparticle. These results show that the damping coefficient can be employed as a typical parameter to characterize the strength of the interfacial region.