Polymers and composites for electrotechnics

Electrical engineering components and systems necessarily incorporate electrical insulation materials between elements carrying different potentials, or for the protection of goods and people. Among these materials, polymers and polymer-matrix composites occupy a very important place, replacing purely inorganic materials (glass or porcelain insulators) or combinations such as oiled paper, whose maintenance and eco-compatibility are weak points. For various reasons linked to :

• the intrinsic performance of materials and the variability of properties depending on their nature;

• changes in the systems themselves;

• conditions of use ;

• recyclability;

• economic considerations;

  These materials are a priority in electrical engineering, as they are in many other fields (aerospace, automotive, construction, etc.). Within electrical systems themselves, the functions they perform and the stresses they must withstand in addition to electrical insulation vary widely. The resistance of organic materials to these various stresses is itself highly variable, depending on their nature and formulation, resulting in a multitude of possibilities from which it is indeed difficult to identify optimal solutions.

Over time, system design has evolved to take account of the possibilities offered by the flexibility of these materials. At the same time, test criteria have been adapted, and the materials themselves have evolved to some extent to suit the constraints of the field. However, the performance of materials in terms of dielectric strength cannot be deduced deterministically from their structure or formulation. This, combined with the fact that potential markets are relatively modest compared with other fields, means that we remain dependent on products offered by the chemical industry, and condemned to carrying out multiple series of tests with stresses and geometries close to service conditions to validate design choices.

The aim of this dossier is to provide the reader with information on the resistance of materials to environmental and service constraints in the field of electrical engineering, and the reasons why certain families of materials may be more suitable than others. In addition to insulation, applications in energy storage (capacitors) are also considered.