Radiation processing of polymer insulators: A method for improving their properties and performance

Polymer insulators for electric apparatus and high‐voltage overhead lines are promising for replacing porcelain and glass insulators. The possibility of this application is shown by radiation‐chemical technology for the manufacture of rodshaped polymer insulators. An ethylene and vinyl acetate copolymer (EVA) was used as the basis for polymer insulators. The composition also contains aluminium hydroxide as a filler and N,N′‐m‐phenylene dimaleimide as a sensitizer. The investigation of γ‐radiation‐induced crosslinking of this composition made it possible to establish the following optimum conditions of radiation processing of insulators: the absorbed dose of up to 200 kGy at a dose rate of 10 kGy/h in air. By forming a three‐dimensional network in the polymer bulk by radiation, the service properties of the insulators are improved: Shape and heat stability is >200°C and the stability to tracking and erosion >200 h. Differential scanning calorimetry (DSC) and a method of stress relaxation were used in evaluation. In the Saint Petersburg region (Russia), several types of high‐voltage (10–110 kV) polymer insulators are manufactured with the application of such radiation‐chemical technology.