Investigation on the Correlation between Dispersion Characteristics at Terahertz Range and Dielectric Permittivity at Low Frequency of Epoxy Resin Nanocomposites.

Ze Lian,Danyang Chen,Shengtao Li

doi:10.3390/polym14040827

Ze Lian, Danyang Chen + Show 1 more

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https://doi.org/10.3390/polym14040827

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Abstract

Despite the extensive research on nanocomposites, a fundamental theory on the interface region is still difficult to achieve. In the present paper, we chose epoxy resin and nano-SiO2, nano-SiC, nano-ZnO to prepare three kinds of nanocomposites. The dispersion characteristics at the terahertz range and dielectric permittivity at 1 Hz of epoxy resin-based nanocomposites were investigated. The reduction of the permittivity of nanocomposites at a slight filler concentration was absent at the terahertz range. The measurement results at 1 Hz show that the interaction between nano-SiO2, nano-SiC particles and epoxy resin was strong with the modification of the silane coupling agent. However, the modification of nano-ZnO particles was invalid. The Lorentz harmonic oscillator model was employed to fit the dispersion characteristics. The relevance between the damping constant and the dielectric permittivity at low frequency was established, indicating that the increase in the damping coefficient results from the restriction of the molecular chain motion by the interfacial region. The present results in this paper reveal a bright prospect of terahertz time-domain spectroscopy in establishing the theory of nanocomposite dielectric.

Highlights

Academic Editor: Dan RosuSince the concept of “nanodielectrics” was first introduced in 1994 by Lewis, it has attracted much attention due to its superior properties and excellent prospect in the electric industry [1,2,3]
The results indicate that the ε” of EP/SiO2 nanocomposites has no evident changes when filler content is lower than 3%
We prepared three kinds of nanocomposites with different filler contents based on epoxy resin

Summary

Introduction

Academic Editor: Dan RosuSince the concept of “nanodielectrics” was first introduced in 1994 by Lewis, it has attracted much attention due to its superior properties and excellent prospect in the electric industry [1,2,3]. Several models were proposed to interpret the superior properties [2,10,11,12], it is still difficult to accomplish a fundamental understanding of the interaction between nanoparticles and poly matrices [8,13]. With the addition of a nano-filler, the molecular motion of polymer is suppressed by the interface region, resulting in the relaxation processes at different frequency ranges exhibiting different changes with the electric field [14]. According to the proposed models, the thickness of the interface region is estimated to be about tens to hundreds of nanometers, depending on filler type, filler size, and the interaction between the nano-filler and the polymer matrix [11]. The terahertz spectrum includes phonon vibration, small molecule rotation, hydrogen bond stretching torsion, and chemical bond low-frequency vibration, which cannot be characterized by Received: 25 January 2022

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