Effects of Polyethylene Structure in Graft‐Modified Polyethylene/Impact Polypropylene Copolymer Blends on the Mechanical and <scp>DC</scp> Electrical Properties of Cable Insulation Material

ABSTRACT Traditional blending methods often lead to a deterioration in the mechanical and electrical properties of polypropylene (PP) cable insulation materials while improving their toughness. To overcome this bottleneck, polyethylene (PE) and impact polypropylene copolymer (IPC) were grafted with maleic anhydride (MAH), respectively. The strong polarity of MAH promotes mutual penetration between IPC and PE, thereby improving the mechanical properties of PE/IPC. Additionally, the deep traps introduced by MAH optimize the material's DC electrical performance. A comparison was made between metallocene polyethylene (mPE), linear low‐density polyethylene (LLDPE), and low‐density polyethylene (LDPE) in terms of their effects on PE/IPC performance before and after MAH grafting. Due to its extremely high regularity, mPE can form effective penetration with IPC, and the performance improvement after grafting modification is the most significant. This effectively addresses the poor mechanical properties of mPE/IPC while maintaining low hardness. The deep traps introduced by MAH result in excellent DC electrical performance of mPE/IPC. In contrast, the branched chain structures of LLDPE and LDPE tend to encapsulate the grafted MAH within the PE phase, weakening the effect of interfacial polar molecular interactions and leading to limited improvements in mechanical and electrical properties.