# Influence of Shear-Induced Pre-Crosslinking on the Mechanical and Dielectric Properties of Crosslinked Polyethylene Cable Insulation

## TL;DR

This paper studies how pre-crosslinking affects the mechanical and electrical properties of crosslinked polyethylene used in power cables.

## Contribution

The study provides insights into optimizing the extrusion process to suppress pre-crosslinking in XLPE cable insulation.

## Key findings

- Pre-crosslinking reduces the crosslinking degree of XLPE.
- Dielectric performance worsens with higher conduction current and lower breakdown strength.
- Controlling pre-crosslinking improves the quality and reliability of XLPE cable production.

## Abstract

Pre-crosslinking reduces XLPE crosslinking degree.

Mechanical properties decline with pre-crosslinking but still meet industry standards.

Dielectric performance deteriorates: higher conduction current; lower breakdown strength.

The experiment results show that the performance of XLPE cable insulation material can be improved by reducing the pre-crosslinking.

The higher pre-crosslinking temperature can reduce but not eliminate the performance degradation.

The results provide key insights for optimizing the extrusion process of high-voltage cables to suppress pre-crosslinking.

Crosslinked polyethylene (XLPE) is a widely used cable insulation material for power cables at various voltage levels, offering excellent electrical, mechanical, and thermal stability. However, during the continuous extrusion moulding process, prolonged shear action and localized temperature accumulation can easily induce premature crosslinking. This leads to a decline in melt rheological properties and reduced processing stability, as well as having an adverse effect on the microstructure and overall performance of the formed insulation layer. This study systematically investigated the impact of shear-induced pre-crosslinking on the mechanical properties and dielectric characteristics of XLPE cable insulation materials through experimental testing methods. The experimental results demonstrate that, while premature crosslinking has a minimal effect on mechanical properties, it significantly deteriorates dielectric performance, as evidenced by increased conduction current, reduced breakdown strength, and compromised microstructural integrity. These findings suggest that, to improve the quality and reliability of XLPE cable production, engineering designs should prioritize controlling the pre-crosslinking process to ensure stable dielectric performance.