This study examined the dielectric properties of linear low density polyethylene (LLDPE)/organo-clay nanocomposites including the same amount of maleic anhydride grafted polyethylene (PE-g-MA) and oxidized polyethylene (OxPE) as compatibilizer at different frequencies (10^-1-10⁺⁷ Hz) and temperatures (237-373 K). The dielectric constant of natural LLDPE remained constant at around 1.5, depending on the temperature rise and frequency while that of LLDPE-PE-g-MA/clay and LLDPE-OxPE/clay nanocomposites increased up to 4.8 and 2.8, respectively, linearly with increasing temperature. Especially in the low frequency region, a Maxwell-Wagner-Sillars polarization was observed in composite structures with an increase in temperature due to the dipolar effect. It has been concluded that the clay in the polymer matrix was more homogeneously dispersed than OxPE due to the compatibilizing effect of PE-g-MA and that different polarization mechanisms were at play for each compatibilizer.

Keywords: low density polyethylene, composites, nanoparticles, polymers, dielectric properties

Low amounts of clay in polymer-clay nanocomposite structures contribute to innovations and advances to develop some properties of polymer materials that are widely used in the industry. Very low amounts of clay or metal oxides doped into polymer matrix are instrumental in increasing the mechanical strength of polymer structures, retarding combustion properties, keeping polymer structures intact up to high temperatures, reducing gas permeability properties, inhibiting the absorption of inorganic liquids, increasing dielectric strengths and developing polymers with lower dielectric constant.^1-19
The aim of this study is to examine in detail the dielectric properties of polymer-clay mixtures. Dielectric studies that investigate molecular drift in polypropylene-clay nanocomposites (Martin et al.),² polarization mechanism of polymeric composite obtained by mixing polypropylene and synthetic clay and electrical conductivity (Antonio et al.),³ dielectric properties of thin film structures prepared according to clay concentration in poly-clay nanocomposites (Wong et al.),^4,5 and the effect of dispersion of clay layers in polymer chains on dielectric properties and dielectric constant of polylactide-clay (Pluta et al.),⁶ and of polymer-clay composite constructions (Rick D. Davis et al.),⁷ are noteworthy.
On the other hand, the interface effect significantly changes the dielectric and mechanical properties of polymer-clay nanocomposite films,^2-4,8-14 which is why different polymeric chemicals referred to as compatibilizers are used to ensure that clay (additive material) is coordinated to the polymeric structure and homogeneously dispersed throughout the structure. This study used two different types of compatibilizers and dielectric spectroscopy method to examine the effect of clay (cloisite southern clay) on dielectric properties and relaxation behavior in the low frequency region depending on the dispersion of the clay in the polyethylene structure.