Issue 42, 2018

Byproduct-free curing of a highly insulating polyethylene copolymer blend: an alternative to peroxide crosslinking

Abstract

High-voltage direct-current (HVDC) cables are a critical component of tomorrow's power grids that seamlessly integrate renewable sources of energy. The most advanced power cable technology uses crosslinked polyethylene (XLPE) insulation, which is produced by peroxide crosslinking of low-density polyethylene (LDPE). Peroxide crosslinking gives rise to hazardous byproducts that compromise the initially excellent purity and cleanliness of LDPE, and hence increase the electrical conductivity of the insulation material. Therefore, a byproduct-free curing process, which maintains the processing advantages and high electrical resistivity of LDPE, is in high demand. Here, we demonstrate a viable alternative to peroxide crosslinking that fulfils these requirements. Click chemistry reactions between two polyethylene copolymers allow the design of a curing process that is additive-free and does not result in the release of any byproducts. The thermoplastic copolymer blend offers a broad processing window up to 140 °C, where compounding and shaping can be carried out without curing. At more elevated temperatures, epoxy and acrylic acid functional groups rapidly react without byproduct formation to form an infusible network. Strikingly, the crosslinked copolymer blend exhibits a very low direct-current (DC) electrical conductivity of 2 × 10−16 S cm−1 at a typical cable operating temperature of 70 °C, which is on par with values measured for both ultra-clean LDPE and commercial XLPE. Hence, the use of polyethylene copolymer blends opens up the possibility to replace peroxide crosslinking with click chemistry type reactions, which may considerably expand the versatility of the most common type of plastic used today.

Graphical abstract: Byproduct-free curing of a highly insulating polyethylene copolymer blend: an alternative to peroxide crosslinking

Supplementary files

Article information

Article type
Paper
Submitted
05 sen 2018
Accepted
24 sen 2018
First published
11 okt 2018
This article is Open Access
Creative Commons BY-NC license

J. Mater. Chem. C, 2018,6, 11292-11302

Byproduct-free curing of a highly insulating polyethylene copolymer blend: an alternative to peroxide crosslinking

M. Mauri, A. Peterson, A. Senol, K. Elamin, A. Gitsas, T. Hjertberg, A. Matic, T. Gkourmpis, O. Prieto and C. Müller, J. Mater. Chem. C, 2018, 6, 11292 DOI: 10.1039/C8TC04494E

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