The Effect of Dispersion Time of Montmorillonite on the Dielectric Properties and Conductivity of Systems Based on Polyethylene Glycol

Abstract

In this work, the effect of ultrasonic dispersion time on the dielectric properties and conductivity of nanocomposites was studied. Model systems based on polyethylene glycol and montmorillonite (PEG-MMT) were prepared. All samples had the same composition and filler content (5% by weight), and the ultrasonic treatment time ranged from 5 to 12 minutes. To determine the dependence of the properties of the systems on the dispersion time, the method of dielectric relaxation spectroscopy was used. It was found that an increase in the dispersion time leads to an increase in the dielectric constant of the systems. The effect of increasing the dispersion time on the dielectric constant in the case of the PEG-MMT system is similar to the effect caused by increasing the nanoclay content due to the decrease in the mobility of the macromolecular segments and the partial intercalation of the polymer into the interlayer space of the MMT. When analyzing the relaxation characteristics of the investigated systems, it was found that as the dispersion time increases, the relaxation regions shift toward higher frequencies, while the relaxation time decreases. This phenomenon is explained by the inhibition of the segmental mobility of the macromolecules due to the increase in the number of steric hindrances caused by the delamination of MMT. In addition, there may have been an increase in the number of charge carriers that are released during the intercalation of the polymer into the interlayer space of MMT, leading to their contribution to the dielectric properties in the form of conductivity relaxation. The experimental values of electrical conductivity at alternating current for the PEG-MMT system were modeled using the Jonscher equation. From the obtained parameters, a change in the degree of interaction between the charge carriers and the matrix was revealed, which is a consequence of the initial delamination of montmorillonite plates, and then their subsequent aggregation into denser structures, the area of interaction with the polymer matrix is much smaller.