Cross-linked polyethylene (XLPE) is commonly used in medium/high voltage insulation due to its excellent dielectric properties and acceptable thermomechanical properties. To improve both electrical and thermal properties to a point that would possibly avoid the need for crosslinking, nanoclay fillers can be added to polymer matrix to form nanocomposites materials. In this paper, PE/clay nanocomposites were processed by mixing a commercially available premixed polyethylene/O-MMT masterbatch into a polyethylene blend matrix containing 80 wt% low density polyethylene LDPE and 20 wt% high density polyethylene HDPE with and without compatibilizer using a corotating twin-screw extruder. Various characterization techniques were employed in this paper, including optical microscopy, AFM, TEM, TGA, DMTA, and dielectric breakdown measurements in order to understand the correlation between structure and short-term dielectric breakdown strength. 1. Introduction Polyethylene is the insulation dielectric material of choice because of its high dielectric strength coupled with low dielectric loss, in addition to lending itself to easy processing. Furthermore, this polymer can be extensively recycled, making it a suitable candidate for replacing its cross-linked counterpart, which has limited recyclability. With conventional composite material, the filler is large or micrometric in size. It has been reported that adding microfiller has a negative effect on dielectric breakdown strength [1] due to the enhancement of the electric field around the aggregated filler particles, leading to decreased breakdown strength. To overcome these limitations, nanocomposite was used as an alternative to replace conventional composite [1–15]. Adding a nanoparticle to the polymer matrix resulted in a decrease in the internal electric field due to the reduction in particle size [16]. It has also been suggested that adding nanoclay can significantly decrease charge accumulation, which leads to increase in dielectric breakdown strength [17]. In nanocomposites, the interface between the nanoclay and the polymer matrix is very large, compared to that of composite or microcomposite materials. Several authors have reported that interface region plays an essential role in improving the insulating performance of nanodielectric materials [18–24]. In this paper, a blend of 80？wt% of LDPE and 20？wt% of HDPE was used as a matrix. The nanocomposite was prepared by melt-compounding the polymer matrix with nanoclay filler using a corotating twin-screw extruder. Only a few studies have focused on the
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