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978-3-8439-1755-1, Reihe Ingenieurwissenschaften
Influence of Nanofillers on High Voltage Polymeric Solid Insulation Systems
193 Seiten, Dissertation Universität Hannover (2014), Softcover, A5
Epoxy resin systems are used under different conditions in various high voltage components. Therefore, their electrical, dielectric, mechanical and thermal properties should be optimized. The influence of a low amount of inorganic nanofillers on conventional epoxy resin systems makes them of interest for many research institutes. Nanofillers combined with organic polymers have been used in order to enhance the electrical, dielectric, mechanical and thermal properties of the insulation materials.
While there are many studies being performed on nanocomposites, only a few evaluate electrical, dielectric, mechanical and thermal properties under new and aged as well as thermally stressed conditions simultaneously. Furthermore, unlike this work, the most current studies are focused on the epoxy resin systems without microfillers.
Considering Al2O3 and TiO2 nanofillers, electrical parameters, such as partial discharge inception voltage, the number of partial discharge impulses, the maximum apparent charge of partial discharge and the breakdown voltage of an indoor and outdoor system were evaluated. The measurements were performed under new and aged conditions at different temperatures below and above the glass transition temperature, taking account of homogeneous and inhomogeneous electrical field configurations, and after applying several thermal stresses. Specific DC volume resistivity, DC surface resistivity, loss factor and permittivity were also measured under new and aged conditions at different temperatures. Only the DC surface resistivity and hydrophobicity of the outdoor system were measured after ageing with ultraviolet radiation. Mechanical and thermal parameters such as tensile strength, tensile modulus, bending strength, bending modulus, as well as thermal conductivity, and glass transition temperature were also evaluated.
The results demonstrate that each of the nanofillers in itself is able to improve some parameters, but it does not affect all parameters necessarily. In this regard, a comparatively general improvement of the partial discharge can be seen in the new and aged conditions, although some results show improper values. After applying thermal stress, the partial discharge behavior of TiO2 nanocomposites with a higher proportion of nanofillers is remarkable.
The nanofillers are also able to improve the mechanical and thermal properties of both epoxy resin systems.
Keywords: nanocomposite, nanofiller, epoxy resin system