Electrical Breakdown Properties of Clay-Based LDPE Blends and Nanocomposites

Abstract

Microstructure and electrical breakdown properties of blends and nanocomposites based on low-density polyethylene (LDPE) have been discussed. A series of LDPE nanocomposites containing different amount of organomodified montmorillonite (clay) with and without compatibilizer have been prepared by means of melt compounding. Two sets of blends of LDPE with two grades of Styrene-Ethylene-Butylene-Styrene block copolymers have been prepared to form cocontinuous structure and host the nanoreinforcement. A high degree of dispersion of oriented clay was observed through X-ray diffraction, scanning, and transmission electron microscopy. This was confirmed by the solid-like behavior of storage modulus in low frequencies in rheological measurement results. An alteration in the morphology of blends was witnessed upon addition of clay where the transportation phenomenon to the copolymer phase resulted in a downsizing on the domain size of the constituents of the immiscible blends. The AC breakdown strength of nanocomposites significantly increased when clay was incorporated. The partially exfoliated and intercalated clay platelets are believed to distribute the electric stress and prolong the breakdown time by creating a tortuous path for charge carriers. However, the incorporation of clay has been shown to diminish the DC breakdown strength of nanocomposites, mostly due to the thermal instability brought by clay.

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

“…The decomposition temperature at 10 wt% and 50 wt% of the nanocomposite sample containing 5 wt% of the compatibilizer (LDPE/MA/5C) is further increased compared to the binary nanocomposite. The possible explanation is the role of MA to improve the degree of dispersion of the clay in the LDPE matrix as it was shown by its broadened XRD pattern .…”

“…This is expected as the MA would be close/attached to the nanofiller due to thermodynamic effects and can be related to the enhancement role of MA on the dispersion of nanofiller within the polymer matrix. The role of compatibilizer is to improve the level of dispersion of clay with the help of the polar interactions between the maleic anhydride groups in the compatibilizer and the hydroxyl groups of clay as was confirmed by the broader diffraction peak in XRD patterns . A similar trend has been reported previously .…”

“…The MWS process occurring in lower frequencies can be explained by the selective localization of nanofiller. In our previous work, it was shown that during the mixing stage, clay has the tendency to leave the polyethylene and migrate into the SEBS phase where it has more affinity towards the aromatic rings of the PS block . Although a number of nanoparticles get stuck in the interface of the two polymer phases, this migration results in the intercalation of the elastomer chains in clay galleries and helps to create a more exfoliated structure by disrupting the regular stacked‐layer structure of nanofiller.…”

“…Because of the combination of the soft elastomer phase and a hard polystyrene phase, their spatial organization can modify the morphology of the blend and selectively accommodate the chosen nanofiller. In fact, in the authors' previous work , it was shown that the greater affinity of clay nanoparticles to the block copolymer resulted in a partial migration of nanofiller out of polyolefin phase to the interface and the SEBS phase, obstructing the coalescence phenomena and shrinking the polymer domains into smaller sizes. This enabled the blend matrix to form a strong network with clay and improved the electrical properties.…”

Effect of regular and core shell nano fillers on the partial discharge and tracking performance of low density polyethylene

“…The length of electrical tree growth in (MMT)/SiO 2 /LDPE is 240 μm compared to 360 μm for pure LDPE at same voltage. LDPE/clay nanocomposites with different filler loadings were prepared to study the improvement in breakdown strength [10]. Breakdown strength increased from 1% − 5% filler loading and then decreased up to 15% filler loading.…”