Effect of LDPE Molecular Structure on the Cross-Linking and Scorching Characteristics of XLPE Material for High-Voltage Cable

There is conflict between crosslinking and scorch resistance of crosslinked polyethylene (XLPE) material for high-voltage cables, and optimizing this relationship through modifications in the molecular structure of low-density polyethylene (LDPE) becomes crucial in the development of high-performance XLPE insulation material. This study utilizes two types of LDPE matrix materials to create crosslinkable polyethylene samples. The LDPE molecular structure is analyzed by gel permeation chromatography (GPC) and Fourier transform infrared spectroscopy (FTIR). The cross-linking efficiency of XLPE samples is evaluated through gel content and thermal elongation tests, and the scorching characteristic of XLPE materials is assessed using a torque rheometer. The findings show that a higher vinyl content in the LDPE molecular structure contributes to increasing gel content and reducing the thermal elongation of XLPE samples. Additionally, a higher weight average molecular weight (Mw) of LDPE leads to more severe scorching of the XLPE material, which adversely affects the extrusion process. This investigation elucidates the effect of LDPE molecular structure on the cross-linking and scorching characteristics of XLPE insulation, offering valuable guidance for achieving long-distance stable extrusion and high crosslinking degree of XLPE insulation material for high-voltage cables.