Abstract
In this thesis, the multilayer PI/nanocomposite films were prepared using an optimized synthesis process. The synthesized samples are characterized by experiments and simulations. First, the samples degradation mechanism was explored using pulse power source. Second, dielectric constant, dielectric loss, insulation lifetime, dielectric strength, conduction current, space charge and thermal stimulated current (TSC) were investigated. Third, trap levels were calculated using total charge decay data and TSC data. In the end, multilayer PI/nanocomposite 3D models based on actual boundary conditions obtained from SEM/TEM images of synthesized samples were constructed in COMSOL Multiphysics software. The impact of nanoparticle dispersion on the electric field enhancement is explicitly described in this model. Our results demonstrate that the chances of nanoparticles agglomeration are reduced by using multilayer structure. In consequence, less space charge and low electrical fields are observed in multilayer films. Using multilayer insulations would ensure reliable operation for electric motors and increase its lifetime.