Epoxy resins are widely used as insulating materials for high-voltage equipment due to their excellent dielectric and thermal stability, but petrochemical-based resins raise environmental concerns. To address this, bio-epoxy composites incorporating epoxidized soybean oil (ESO) were prepared by blending diglycidyl ether of bisphenol A (DGEBA) and ESO at a 7:3 ratio with 65 wt% micro-silica filler. Their electrical properties, including relative permittivity, dielectric loss tangent, electrical conductivity and AC breakdown strength, were evaluated, and accelerated stress tests were conducted to obtain lifetime data. The results were statistically analyzed using normal, Weibull, log-normal, exponential, and gamma distributions, and goodness-of-fit tests identified the most suitable model. This work demonstrates a statistical approach for assessing the electrical insulation performance of bio-epoxy composites as eco-friendly insulating materials.
Cheon et al. (2026) studied this question.