The evaluation of the early ageing period of castings made of epoxy and PUR resins

The paper deals with the resistance of hydrophobicity on different castings made of epoxy or PUR resins. Model insulators were aged in a Modified Rotating-Wheel-Dip Test (MRWDT). The state of ageing was evaluated by on-line measurements of the leakage current and PD-measurements. The chemical changes at the surfaces were investigated with methods such as SEM, EDX, ESCA and zeta-potential. The influence of the cyclic immersion of the specimens in the electrolyte solution during the MRWDT was evaluated separately.