Epoxy composites for insulating properties

Among materials used for electrical insulation in power electronics systems like IGBT, silicone elastomers used are considered as good candidates but are limited to 180–200°C. In this work, new thermoset/thermoplastic composites are investigated. The addition of some thermoplastics to epoxy amine systems can lead to system exhibiting phase separation. The thermal degradation under some conditions reaches 300°C, which is interesting for power electronics applications. The mixture of thermoplastic inside epoxy prepolymer governs the final microstructure. For example, the addition of 10 % wt of PEI gives inclusions of thermoplastic with a micrometer size. Even if the T alpha of epoxy matrix was changed upon the addition of PEI, the dielectric spectroscopy points out that the addition of some thermoplastic decreases the permittivity compared with the pure epoxy amine network.