Byproduct-free curing of a highly insulating polyethylene copolymer blend: An alternative to peroxide crosslinking
Journal article, 2018

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.

Peroxides

Polyethylene

Curing

HVDC power transmission insulation

Synthesis (chemical)

Blending

Byproducts

Electrical power transmission networks

Electrical conductivity

Oxidation

Polymer blends

Cables

Author

Massimiliano Mauri

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Polymer Technology

Anna Peterson

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Christian Müller Group

Khalid Elamin

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Anna Martinelli Group

Antonis Gitsas

Borealis GmbH

Thomas Hjertberg

Borealis AB

Aleksandar Matic

Chalmers, Physics, Condensed Matter Physics

Thomas Gkourmpis

Borealis AB

Oscar Prieto

Borealis AB

Christian Müller

Chalmers, Chemistry and Chemical Engineering, Applied Chemistry, Christian Müller Group

Journal of Materials Chemistry C

2050-7534 (ISSN)

Vol. 6 42 11292-11302

Subject Categories

Polymer Chemistry

Chemical Process Engineering

Polymer Technologies

DOI

10.1039/c8tc04494e

More information

Latest update

11/25/2018