Enhancing Dielectric Properties: Improved Interfacial Adhesion of Polypropylene/Ultra-High Molecular Weight Polyethylene Nanocomposites for Power Cables

This work highlights the potential of polypropylene (PP) as a power cable insulation material by blending with ultrahigh molecular weight polyethylene (UHMWPE), as well as blends filled with magnesium oxide (MgO) nanoparticles. In PP/UHMWPE blends, increasing the UHMWPE content up to 50 weight percentage (wt.%) increases the number of interfaces between PP and UHMWPE, promoting heterogeneous surface nucleation and strengthening the interfacial adhesion. This enhanced interfacial adhesion in PP/UHMWPE blends results in improved dielectric properties, particularly reduced relative permittivity, suppressed charge accumulation, and decreased dc electrical conductivity. In PP/UHMWPE/MgO nanocomposites, MgO nanoparticles are primarily observed at the interface between PP and UHMWPE in the PP phase. The presence of MgO does not function as a nucleating agent; instead, it acts as a compatibilizer, promoting the dispersion of UHMWPE and enhancing the interfacial adhesion between both polymers. The improved dispersion of UHMWPE results in the nonformation of phase co-continuity within the PP matrix; consequently, adding MgO up to 3 wt.% is insufficient to establish the interfaces forming percolating pathways. Thus, the good dispersion and compatibilizing effect of MgO between the PP and UHMWPE interfaces enhance interfacial adhesion and further improve the dielectric properties compared to the unfilled PP/UHMWPE blend counterparts.