Characterization of Isotactic-Polypropylene-Based Compounds for HVDC Cable Insulation

This paper aims at a preliminary characterization of isotactic-polypropylene-based blends as a candidate to be used for High-Voltage Direct Current HVDC cable insulation in the framework of the European project NEWGEN (New GENeration of HVDC insulating materials, cables and systems). Isotactic-polypropylene (i-PP) is blended with various propylene-based elastomers (PBEs) and heterophasic PP random copolymers (HECO) with different percentages. Results show that, compared to XLPE, i-PP blends have a comparable breakdown strength, but higher DC conductivity. Noticeable space charge accumulation is observed in the i-PP blends. TSDC measurements show that i-PP blends are characterized by two great peaks (that attribute shallow and deep traps) compared to only one deep-trap peak in the XLPE.