The internationally growing demand for electrical energy is one of the most prominent triggers stimulating research these days. In this highly interdisciplinary research area, electrical engineers, material scientists and chemists collaborate for the design and fabrication of the next generation of high-voltage machinery and electro-technical devices. Nanocomposites with enhanced thermal conductivity and improved electric properties are in the center of these joint research activities. Hence, in this Special Issue of the open-access journal Polymers, the state-of-the-art research and technology of the area ‘micro- and nanocomposites for electrical engineering applications’ has been summarized in three review articles, while the current research trends and the development and characterization of novel materials have been described in eight original research articles.

State-of-the-art of research and technology. The comprehensive review article by Plesa et al. addresses with dedication the structure-property relationships of composite materials with special respect to their electric properties and the resulting potential application fields. Originating from the high demands regarding the reliability and lifetime expectance of high-voltage engineering machineries such as generators and transformers, the mechanical properties of insulating resins and the corresponding micro- and nanocomposites are of prime importance; this topic has been summarized in the review article by Moser and Feuchter, in which epoxy-based resins are discussed in detail. Mica/epoxy composites are the most commonly used insulation materials in high-voltage rotating machines, and their properties as well as the possibly occurring failure mechanisms of the composite material have been described in the review article by Andraschek and colleagues.