A Differential Temperature-Dependent Dielectric Relaxation Study of Organoclay Cloisite$^{\mathrm{TM}}$

Abstract

We report variation in the dielectric relaxation profiles of an important class of commercially available Cloisite $^{\mathrm{TM}}$ organoclays, 25A, 15A, 30B and 10A, which are extensively used as rheology modifiers. A systematic and comprehensive comparison is made of their dielectric permittivity (${{\upvarepsilon }^{\prime }})$, and loss (${{\upvarepsilon }^{\prime \prime }})$, conductivity (${\upsigma }^{\prime })$ and loss tangent ($\tan \delta )$ parameters as function of temperature. The dispersion profiles showed relatively higher values for ${{\upvarepsilon }^{\prime }}$, ${\upvarepsilon }^{{\prime \prime }}$, ${\upsigma }^{\prime }$ and $\tan \delta$ for the Cloisite$^{\mathrm{TM}}$30B samples in low-frequency region. A clear temperature-dependent transition in the values of ${{\upvarepsilon }^{\prime }}$ and ${{\upvarepsilon }^{\prime \prime }}$ was noticed for Cloisite$^{\mathrm{TM}}$25A sample at 436 K, which was independent of frequency, $\omega$. The values of ${{\upvarepsilon }^{\prime }}$ and ${{\upvarepsilon }^{\prime \prime }}$ showed $1/\omega$ dependence with temperature. Cloisite$^{\mathrm{TM}}$30B sample showed a marked decrease in the value of $\tan \delta$ with increase in temperature compared to other samples. Thus, it was concluded that these clays bear signature dielectric properties regardless of the fact that they all belong to the same structural class of clays. Considering the large-scale use of these clays in many industrial products the above-mentioned results are of significant importance.