Optimization and Comparative Analysis of Stoichiometry and Additives for Enhancing Thermomechanical, Dielectric, and Wetting Properties of Epoxy Resin in <scp>GIS</scp> Insulation Rods

ABSTRACT Epoxy resin serves as a critical insulating material for gas‐insulated switchgear (GIS) components, yet achieving a balance between its mechanical properties, dielectric performance, and interfacial behavior under coupled electromechanical stress conditions remains challenging. This study systematically optimized the epoxy resin/anhydride curing system by adjusting the anhydride ratio and incorporating functional additives to enhance network structure and fiber‐matrix compatibility. Epoxy samples with varying anhydride dosages were prepared, and the effects of silicone‐based defoaming and wetting agents were evaluated. Results indicate that increasing anhydride content from 80 to 110 phr causes curing degree, hardness, residual carbon content, and storage modulus ( E ′) to initially rise then decline, with optimal performance at 93 phr. Compared to the theoretical stoichiometric ratio (96–100 phr), this formulation exhibits higher crosslink density and a 2°C–10°C increase in glass transition temperature ( T g ). The introduction of additives effectively suppressed internal voids, enhanced resin spreadability, and strengthened interfacial adhesion with aramid fibers. Consequently, the dielectric constant decreased from 2.8 to 2.5, and the contact angle decreased from 97.7° to 84.3°. These findings provide practical and theoretical guidance for formulating GIS‐grade epoxy resin systems that enhance reliability and insulation performance.