Fecha de publicación: -- Fuente: Journal of applied polymer Lugar: RESEARCH ARTICLE Polypropylene structure and content govern the electrical–mechanical response of peroxide-crosslinked EPDM cable-accessory insulation. Homopolymer PP shows higher crystallinity and enhanced high-temperature electrical performance relative to random-copolymer and block-copolymer PP. Increasing H-PP content improves breakdown strength and resistivity but reduces compliance, while 5 wt% maintains high extensibility and provides a favorable overall performance balance.

ABSTRACT
Cable accessories are weak points in high-voltage systems, imposing stringent requirements on insulation materials. In this work, EPDM was modified with polypropylene (PP) of different molecular structures and contents to clarify structure–property relationships. Among random-copolymer PP (R-PP), block-copolymer PP (B-PP), and homopolymer PP (H-PP) compared at the same content, H-PP exhibited the highest crystallinity and showed superior electrical performance, particularly at elevated temperatures. Meanwhile, H-PP also enhanced tensile strength, elastic modulus, and thermal conductivity while retaining a high elongation at break. Increasing the H-PP content from 0 to 15 wt% further increased the crystallinity from approximately 0.3% to 6.1%, with only minor changes in crosslinking density. As a result, the AC breakdown strength, volume resistivity, tensile strength, and thermal conductivity were progressively improved, while the relative permittivity and dielectric loss remained comparatively stable. However, high H-PP contents markedly increased the elastic modulus and reduced the elongation at break, revealing a trade-off between reinforcement and mechanical compliance. Among the investigated formulations, 5 wt% H-PP provided the most balanced combination of electrical performance, mechanical strength, and deformability. These results demonstrate that optimizing PP structure and content provides an effective approach for improving the comprehensive properties of EPDM for cable accessory insulation.