Research Progress in Treeing Phenomena of Polypropylene Insulation Materials

ABSTRACT

Polypropylene (PP) is increasingly utilised in high‐voltage systems due to its superior electrical and thermal properties. However, electrical treeing poses a significant threat to its long‐term reliability, potentially leading to insulation failure. This review examines the mechanisms of electrical treeing initiation and propagation in PP insulation under various voltage conditions, including AC, DC and superimposed voltages, with particular emphasis on the coupled effects of electrical, thermal and mechanical fields. Repetitive partial discharge serves as the fundamental driving force behind electrical tree initiation and accelerated growth. Furthermore, the propagation of electrical trees reveals that the distribution of crystalline and amorphous regions of polypropylene significantly governs degradation pathways. This review discusses resistance strategies, specifically organic molecular modification, nanoparticle incorporation and crystalline structure regulation. Despite these advances, current research remains limited in understanding the synergistic interactions among multi‐physical fields and in developing predictive models for long‐term treeing behaviour. Future efforts should focus on the design of hierarchically structured PP composites to further enhance insulation performance. These insights are crucial for advancing the development of reliable insulation materials for next‐generation high‐voltage systems.