Properties Comparison of Liquid Silicone Rubber Insulation Materials for Typical Cable Accessories at Home and Abroad

In order to evaluate the differences in electrical and mechanical properties between typical domestic and imported liquid silicone rubber (LSR) for cable accessories, LSR specimens from different domestic and foreign manufacturers were adopted as research objects. The influences of secondary vulcanization and thermal aging on the electrical and mechanical properties of domestic and imported materials were systematically investigated. The results indicate that after secondary vulcanization, the electrical breakdown strength of domestic LSR shows no obvious variation, while the volume resistivity and tear strength are greatly enhanced, with the increment of tear strength ranging from 79.2% to 113%. The tensile properties of domestic materials either rise or decline, and their overall mechanical properties are superior to those of imported ones. For imported LSR, although the volume resistivity is remarkably improved, the electrical breakdown strength generally decreases with a maximum reduction of approximately 8.1%. The tensile properties of a few materials have declined, and the initial crosslinking structure is already relatively complete, leaving limited room for improvement in tear strength. After thermal aging, the volume resistivity of both domestic and imported LSR partially increases and partially decreases. The electrical breakdown strength of domestic materials slightly declines, their tensile properties remain generally stable, and the tear strength undergoes attenuation. For imported materials, both the electrical breakdown strength and tear strength partially decrease while some increase reversely; the tensile strength stays stable but the elongation at break decreases significantly, with a maximum reduction of 29.3%. This work provides data support and theoretical basis for material selection and process optimization of cable accessories, and presents important engineering application value.