Improvement of Dielectric Breakdown Performance by Surface Modification in Polyethylene/TiO2 Nanocomposites.

Weiwang Wang,Shengtao Li

doi:10.3390/ma12203346

Abstract

Dielectric breakdown is a significant property for the insulation system in high voltage power equipment. This paper is dedicated to the improvement of dielectric breakdown by surface-functionalized nanoparticles in low-density polyethylene (LDPE). Prior to the preparation of LDPE/TiO2 nanocomposites, the nanoparticles were surface modified by the silane coupling followed by the chemical reaction process. Results of Fourier transform infrared spectroscopy (FTIR) indicated that some polar groups and chemical bonding were introduced on the surface of TiO2 nanoparticles. A reduction of dielectric permittivity was observed at low nanoparticle loading (<2 wt%) samples, which responded to the restriction of the molecular chain in the interface region. High nanoparticle loadings (2 wt%, 5 wt%, 10 wt%) introduced an obvious relaxation polarization. The trap parameters detected by the thermally stimulated current (TSC) method indicated that the deep traps were introduced by small amounts of nanoparticles (≤2 wt%), while more shallow traps occurred in high loading (5 wt%, 10 wt%) samples. Meanwhile, the increase of breakdown strength at low loading samples were closely related to the deep traps, which was ascribed to the interface region by surface chemical modification.

Highlights

The incorporation of inorganic nanoparticles into the polymer matrix opens a new pathway for engineering flexible composites that exhibit advantageous electrical [1], mechanical, and thermal properties [2]
In order to study further the link between the surface modification of nanoparticles and the dielectric breakdown, this paper focused on the effects of surface chemical treatment of TiO2 on the dielectric breakdown of low-density polyethylene (LDPE) nanocomposites
It turned out that the large amounts of TiO2 nanoparticles contributed to the shallow traps in the nanocomposites

Summary

Introduction

The incorporation of inorganic nanoparticles into the polymer matrix opens a new pathway for engineering flexible composites that exhibit advantageous electrical [1], mechanical, and thermal properties [2]. Polymer nanocomposites with a well-dispersed homogeneous blend present favorable electrical properties, such as decreasing dielectric permittivity, improving electric strength, restraining space charge accumulation, and improving partial discharge (PD) resistance [3]. The dielectric breakdown performance has been studied in polyethylene nanocomposites with various nanofillers, especially for the surface chemical modifications. Polyethylene/montmorillonite (MMT) clay nanocomposites exhibit reduced breakdown strength with the poorly dispersed MMT nanofillers, while the increase of breakdown strength occurred in the good dispersion nanocomposites with much more irregular lamella structures (an increase in the αvalue from ~120 to ~180 kV/mm) and an increase in β from. Previous papers have been focused on the breakdown strength in low-density polyethylene (LDPE) nanocomposites [6,7,8]. The results pointed out that slight nanofillers (2 wt%) reduce the breakdown

Results

Discussion

Conclusion