Study on the Preparation and Properties of Polypropylene Cable Insulation Material Modified With Cycloolefin Copolymer

ABSTRACT Polypropylene (PP) is a promising recyclable cable‐insulation material, but its poor low‐temperature toughness limits application in cold regions. In this work, cycloolefin copolymer (COC) was introduced into PP by melt blending, with maleic anhydride‐grafted polypropylene (PP‐g‐MAH) used as a compatibilizer, to improve mechanical toughness while maintaining favorable dielectric performance. The effects of COC content on morphology, crystallization, mechanical behavior, and electrical properties were systematically investigated. An appropriate COC content refined PP spherulites and produced a well‐dispersed sea–island morphology with improved interfacial adhesion. At 6 wt% COC, the embrittlement temperature decreased from −30°C to −52°C while the elongation at break remained 513.8%. Meanwhile, electrical conductivity was suppressed, dielectric loss remained low, and the DC breakdown strength increased from 30.1 to 34.6 MV m −1 . These results demonstrate that COC modification provides an effective route to balance low‐temperature toughness and electrical insulation performance in recyclable PP‐based cable materials.