PE/clay nanocomposites were prepared by mixing a commercially available premixed polyethylene/O-MMT masterbatch into a polyethylene blend matrix containing 80？wt% low-density polyethylene and 20？wt% high-density polyethylene with and without anhydride modified polyethylene (PE-MA) as the compatibilizer using a corotating twin-screw extruder. In this study, the effect of nanoclay and compatibilizer on the structure and dielectric response of PE/clay nanocomposites has been investigated. The microstructure of PE/clay nanocomposites was characterized using wide-angle X-ray diffraction (WAXD) and a scanning electron microscope (SEM). Thermal properties were examined using differential scanning calorimetry (DSC). The dielectric response of neat PE was compared with that of PE/clay nanocomposite with and without the compatibilizer. The XRD and SEM results showed that the PE/O-MMT nanocomposite with the PE-MA compatibilizer was better dispersed. In the nanocomposite materials, two relaxation modes are detected in the dielectric losses. The first relaxation is due to a Maxwell-Wagner-Sillars interfacial polarization, and the second relaxation can be related to dipolar polarization. A relationship between the degree of dispersion and the relaxation rate of Maxwell-Wagner-Sillars was found and discussed. 1. Introduction There has been growing interest in polymer/nanoclay nanocomposites in recent years because of their outstanding properties at low loading levels as compared with conventional composites. It has been observed that adding small quantities of nanoclay to some thermoplastics as a reinforcing filler to form nanocomposite materials has not only led to more improved mechanical and thermal properties, but also to an enhancement of the dielectric strength and partial discharge resistance [1–10]. However, the understanding of the role of the interfaces of the nanofillers with the molecular mobility mechanism is still rather unsatisfactory. Although there are different processing methods for preparing nanocomposites, the most widely used technique is the melt-compounding method using a twin-screw extruder, because this technique features economic benefits and ecological advantages. The main challenge in the fabrication of nanocomposites is dispersion of the individual clay platelets into the polymer matrix, due to the incompatibility of hydrophobic matrix with hydrophilic nanoclay [11]. Rendering clay platelets more hydrophobic requires a surface treatment, which is accomplished via ion-exchange reactions with cationic surfactants using quaternary alkyl
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