Dielectric and Mechanical Behavior of Toughened Epoxy Resin for Dry Cable Termination Under Low Temperature Conditions

The performance of epoxy‐based power equipment is severely constrained under low‐temperature conditions by the reduced fracture toughness of epoxy resin, which promotes crack propagation and partial discharge. In this paper, a cost‐effective toughener is synthesized by combining epoxy‐terminated phenyltris(dimethylsiloxy)silane (PTDS) with allyl glycidyl via a hydrosilylation reaction to enhance the low‐temperature performance of traditional epoxy resin. The elongation at break of the modified epoxy resin increases from 3.69% to 5.81% at room temperature (RT) and from 2.63% to 5.05% at −40°C, while fracture toughness rises from 1.065 to 1.476 MJ·m −3 at RT and from 0.882 to 1.209 MJ·m −3 at −40°C. β‐relaxation loss under the electric field is suppressed due to the introduction of a non‐polar molecular structure. With 10 wt% toughener content, partial discharge inception voltage (PDIV) is markedly elevated, and discharge severity is suppressed, showing improved dielectric functionality. Nevertheless, dynamic mechanical analysis (DMA) reveals that the modification progressively decreases storage modulus E ', with the 10 wt% sample showing a 19% reduction versus the neat epoxy resin. Performance balance and optimization should be carried out when the modified epoxy resin is applied to high‐voltage power equipment in low‐temperature conditions.