Study on Aging Characteristics of Polypropylene Based on Electrical Conductivity and Space Charge

Polypropylene is regarded as an ideal electrical insulating material due to its excellent dielectric properties, mechanical strength, wide temperature range of use and chemical stability. In order to further study the aging properties of polypropylene, this paper measured the DC conductivity and space charge distribution of unaged and aged 24 h and 168 h polypropylene materials at 30° C and <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$1-60 \text{kV} / \text{mm}$</tex> electric field strength. The results showed that with the increase of aging time, the polypropylene conductive current increased significantly, the conductivity increased, and the conductivity threshold electric field decreased and then increased; the space charge measurements showed that the space charge density inside the specimen decreased after aging due to the change of the type of internal traps. Conductivity and space charge interact with each other and together reflect the evolution of the internal microstructure and carrier behavior of the material. The study shows that in-depth investigation of the conductivity and space charge characteristics of polypropylene materials after aging is of great significance for optimizing the design of power cables, improving operational reliability and extending service life.