Evaluation of Copper Catalytic Effects in Cable Insulation Polymers
This paper summarizes work performed to evaluate a phenomenon that occurs in electrical cable insulation polymers subjected to accelerated aging while in contact with copper metal. This effect, commonly known as the copper catalytic effect, is a result of chemical reactions that occur when copper ions diffuse into insulation polymers. This diffusion process is observed in various types of polymeric materials exposed to elevated temperatures and happens at the interface between the insulation and metallic components (e.g., conductor, shielding, etc.) in a cable. This polymer-metal interaction has only been observed in cables constructed with copper components (i.e., no interactions observed in cables with aluminum or other metal conductor/shielding) and results in a significant catalytic effect that increases the oxidation rate (e.g., aging) of the material. Under this research, the copper catalytic effects observed in cross-linked polyethylene, cross-linked polyolefin and ethylene propylene rubber insulated cables subjected to thermal accelerated aging were evaluated. These evaluations involved applying infrared spectroscopy, microscopy, and energy dispersive X-ray spectroscopy cross-sectional depth profiling to obtain an in-depth understanding of the aging characteristics of the materials under accelerated conditions. Based on the results of these assessments, the copper catalytic effect can have a significant impact on the mechanical, thermal, chemical, and electrical properties of cable insulation polymers. Here, the results acquired from this research provided the information needed to characterize the copper catalytic effects observed in these polymers, analyze how this phenomenon affected the polymer degradation process, and compare and understand the differences in the properties of the materials.