Why Does The Dielectric Constant Of Epoxy Resin Insulators Remain Stable Within A Moderate Range?

high voltage epoxy resin is a typical polar polymer, containing polar functional groups such as hydroxyl groups, ether bonds, and epoxy groups in its molecular chain. These polar groups can undergo orientational polarization or interfacial polarization under the action of an external electric field, thereby increasing the relative permittivity. However, the permittivity of high voltage standoff does not reach a higher value because the three-dimensional cross-linked network structure formed after curing restricts the free rotation and polarization degree of the polar groups. The structure of high voltage standoff insulators keeps the total permittivity of the material stable in a moderate range.