Surface behaviour of epoxy castings during the early ageing period

This paper discusses the phenomena of the surface degradation in the early ageing period (EAP) under indoor conditions. The surface hydrophobicity of aromatic epoxy resin with different fillers was investigated. The lifetime of the insulating materials depends on their withstand against combined electric and climatic stress. The climatic stress is initiated by the humidity of the environment. To evaluate the surface hydrophobicity of insulating materials, a Modified Rotating-Wheel-Dip-Test (MRWDT) with different dipping liquids was used. To separate the influence of the humidity in the MRWDT from the combined stress, specimens were immersed in the used liquids. The processes of ageing are discussed by using the results of both methods and chemical analyses of the aged specimens.