Mechanical and Insulation Properties of Elastomer-Toughened Polypropylene Ternary Blends for Highvoltage Power Cable Applications

Recently, polypropylene (PP) has gained considerable attention as a promising next-generation insulation material for power cables, serving as an alternative to crosslinked polyethylene (XLPE), and efforts have been made to make the PP flexible. In this study, we report an insulative PP-based ternary blend with high toughness, in which a high content of elastomeric dispersed phases is distributed in the iPP matrix. The ternary blend is prepared through melt-mixing of the isotactic PP (iPP), polyolefin elastomer (POE), and PE-PP block copolymer (BCP). The tensile modulus of the ternary blend is largely reduced by 228.3 MPa, meeting requirement as power cable insulation material. The ternary blend exhibits a higher tensile strength of 14.1 MPa and elongation at break of 717.8% compared to those of XLPE. Also, the ternary blend shows a high melting temperature of 164.9 °C, whereas XLPE has a melting temperature of 106.9 °C. Interestingly, the ternary blend also demonstrates excellent toughness at -40°C as well as 20°C, whereas the binary blend without BCP shows poor toughness. Moreover, although the ternary blend possesses a large fraction of the amorphous phases arising from the POE, it exhibits volume resistivity and DC breakdown strength values comparable to those of XLPE.