Optimalization of the Thermal Curing of Epoxy Based Insulations

There is difficult to imagine modern production of electrical devices without components containing organic substances. This fact is mainly concerned to composite materials, in which the bond component is made of organic substance. The intricate curing reactions have been proceeding during the composites technological curing as well as during the device operation, where mostly the thermal-oxidative reactions, leading to material degradation, occur. For above-mentioned reasons, there is given big attention to the study of the reactions proceeding in the material. Monitoring of the properties and applicability of high-voltage insulating systems containing epoxy resins require knowledge of curing degree of these resins. This curing degree is considered to be the key parameter for quality of materials used for these systems. Application of Differential Thermal Analysis (DTA) for evaluation of curing degree of three-component composite materials (glass fabric, reconstructed mica, epoxy resin) is presented in the article. Used analysis enables to observe characteristic structural parameter – the concentration of reactive particles in organic component of this material. In our investigation, concept of curing reactions courses was obtained as well as the details for determination of optimal curing time of material. These conclusions have been confronted with the other methods such as Thermomechanical Analysis (TMA) or dissipation factor and complex permitivity determination. Based upon these results it is obvious, that the conclusions correspond to one another. Electrical properties of high voltage-high temperature insulation materials depend on the curing degree of the used resin. The new modified high temperature resistant epoxy resins were used in the three-component composite materials. The main objective of the investigation was to obtain the material with the best electrical properties.