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Abstract
Among various types of materials for electrical insulation in power system equipment, polymers have been commonly used for more than five decades. They are usually manufactured with additives to meet design requirements. Intense researches are currently focused on nanocomposites, which are synthesized with nano-scale particles as fillers and conventional polymers as matrices. The key challenges yet to overcome are the poor dispersion and the low filler-matrix interactivity. In this thesis, plasma technology, for the very first time, is utilised to engineer the surface of the nanoparticles for fabricating nanocomposites with advanced dielectric and electrical insulation properties. First, an atmospheric-pressure plasma (APP) system is developed. APPs carried by inert gas are employed to tailor the surface of silica nanoparticles with existing silane functional groups. In addition, a plasma polymerization system is developed to provide an alternative fabrication process, where the plasma is carried out under low pressure with specified monomers. In this case, plasma polymerization takes place on the pure silica nanoparticles and functional plasma polymer layers can be coated on their surfaces. For both methods, results of chemical and morphological characterization indicate that the filler-matrix bonding is enhanced and the dispersion is improved in the epoxy resin-based nanocomposites. Electrical tests showed improved partial discharge (PD) characteristics, breakdown strength, and resistance to electrical ageing, space charge distribution, and dielectric constant in the nanocomposites with plasma modified fillers. These improvements can be explained from the perspective of the immobilization of polymer molecules by the reinforced filler-matrix bonding, carrier trapping effects by the altered electrical double layer around the nanoparticles, and the barrier effects by good dispersion of the nanoparticles. The outcome of this research provides an effective, economic, and environment-friendly approach for synthesizing high performance nanocomposite insulation materials. It is generic that can be utilised in the fabrication of novel nanocomposites for a wide range of applications.