Functionalization of Silica Nanoparticles to Improve Crosslinking Degree, Insulation Performance and Space Charge Characteristics of UV-initiated XLPE

Abstract

In order to inhibit the outward-migrations of photo-initiator molecules in the ultraviolet-initiated crosslinking process and simultaneously improve the crosslinking degree and dielectric properties of crosslinked polyethylene (XLPE) materials, we have specifically developed surface-modified-SiO2/XLPE nanocomposites with the silica nanofillers that have been functionalized through chemical surface modifications. With the sulfur-containing silanes and 3-mercaptopropyl trimethoxy silane (MPTMS), the functional monomers of auxiliary crosslinker triallyl isocyanurate (TAIC) have been successfully grafted on the silica surface through thiol–ene click chemistry reactions. The grafted functional groups are verified by molecular characterizations of Fourier transform infrared spectra and nuclear magnetic resonance hydrogen spectra. Scanning electronic microscopy (SEM) indicates that the functionalized silica nanoparticles have been filled into polyethylene matrix with remarkably increased dispersivity compared with the neat silica nanoparticles. Under ultraviolet (UV) irradiation, the high efficient crosslinking reactions of polyethylene molecules are facilitated by the auxiliary crosslinkers that have been grafted onto the surfaces of silica nanofillers in polyethylene matrix. With the UV-initiated crosslinking technique, the crosslinking degree, insulation performance, and space charge characteristics of SiO2/XLPE nanocomposites are investigated in comparison with the XLPE material. Due to the combined effects of the high dispersion of nanofillers and the polar-groups of TAIC grafted on the surfaces of SiO2 nanofillers, the functionlized-SiO2/XLPE nanocomposite with an appropriate filling content represents the most preferable crosslinking degree with multiple improvements in the space charge characteristics and direct current dielectric breakdown strength. Simultaneously employing nanodielectric technology and functional-group surface modification, this study promises a modification strategy for developing XLPE nanocomposites with high mechanical and dielectric performances.

Bionic ordered structured hydrogels: structure types, design strategies, optimization mechanism of mechanical properties and applications

“…112,184,185,187 This can be achieved by constructing ordered double network hydrogels, 20 introducing metal ions for coordination (Fig. 5A), 172 adding SiO 2 nanoparticles 188 and other methods. These techniques can increase the crosslinking density either directly or indirectly in the bionic ordered structured hydrogels.…”

Dielectric Characteristics of Crosslinked Polyethylene Modified by Grafting Polar-Group Molecules

“…Graft modification is a molecular-level technology of chemically introducing specific functional groups into polymer backbone to promote intrinsic electrical properties of insulation materials used for fabricating HV power cables. Organic compounds with polar groups, such as carbonyl (C=O), used for graft modifications, are competent in reducing charge carrier mobility, ameliorating space charge characteristics, and acting as inhomogeneous nucleation centers to increase polyethylene spherulite density, which account for the holistic improvements in electric-tree resistant performance, insulation strength, and water-tree aging resistance, respectively [ 29 , 30 , 31 , 32 , 33 ]. It is a comprehensive scheme of suppressing the space charge accumulations and enhancing electric resistance of ethylene/α-alkenes copolymers by chemically introducing polar groups, such as ethyl, hydroxyl, nitro, cyanyl, or aromatic ring to improve the electrical performances of power cables under a polar reversal.…”

Molecular Dynamics Simulations on Epoxy Resin Composite via Grafting Acryloyl-chloride to Inhibit Electron Transport and Improve Thermal-mechanical Properties

“…Organic compounds with polar functional groups used for grafting modification, such as carbonyl (C=O), can improve space charge characteristics, reduce charge carrier mobility, and act as non-z E-mail: zhliu@ytu.edu.cn; wang_lei@btbu.edu.cn ECS Journal of Solid State Science and Technology, 2024 13 053007 uniform nucleation centers to increase the density of polyethylene spherulites, which respectively demonstrate the overall improvement of water tree aging resistance, electrical tree resistance and insulation strength. [21][22][23][24] This is a method of improving the electrical performance of power cables under polarity reversal by chemically introducing polar groups (such as hydroxy,lethyl, cyano,nitro, or aromatic rings), thereby suppressing ethylene/α-A comprehensive solution for the accumulation of space charge in olefin copolymers and the improvement of their resistance. In the crosslinking reaction initiated by polyethylene photons, the modification of 4-vinyloxyphenylacetone onto polyethylene molecular chains was successfully achieved, which can effectively prevent functional group compounds from migrating from the polymer matrix and significantly improve the DC dielectric properties of crosslinked polyethylene (XLPE).…”