LDPE/HDPE/Clay Nanocomposites: Effects of Compatibilizer on the Structure and Dielectric Response

Abstract

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 ratefmaxof Maxwell-Wagner-Sillars was found and discussed.

Dielectric Relaxation Dynamics of Clay‐Containing Low‐Density polyethylene Blends and Nanocomposites

“…However, no separate dielectric relaxation can be spotted for MA compatibilizer. Similar behavior has been reported in the literature .…”

“…A double peaks structure gradually develops in the nanocomposites representing two relaxation modes arising from the addition of clay nanofiller into the base polymer. This double peak structure has been previously reported for polymer/clay nanocomposites .…”

“…Taking a step forward, the idea of incorporating a secondary polymer as compatibilizer to facilitate the interaction/dispersion of nanofiller in the base polymer , or forming a polymer blend matrix as a nanostructured template to effectively host the nanofiller have been examined recently especially in the context of HV applications. Blends of thermoplastic elastomers with polyolefins have also been investigated recently.…”

Correlation between Structure and Dielectric Breakdown in LDPE/HDPE/Clay Nanocomposites

“…A better dispersion of the clay platelets was achieved for PE/O-MMT/PE-MA than for the nanocomposites without a compatibilizer. This result is in agreement with our previous SEM and XRD measurements [28]. Figure 4 parameters derived from these curves are given in Table 3.…”

“…When the compatibilizer was added to PE/O-MMT nanocomposites, a further improvement in breakdown strength was noticed. This may suggest a correlation between morphology and breakdown strength and that dielectric characterization, especially breakdown strength and dielectric response [28] measurements, can be exploited as an indirect technique for evaluating the degree of dispersion of nanoclay layers in polymer nanocomposites. Further studies will be necessary to confirm the results obtained.…”