Structure and Dielectric Properties of Maleic Anhydride Compatibilized and Thermally Aged Polypropylene Blends

ABSTRACT Polypropylene (PP)‐based materials have been increasingly considered as sustainable insulation alternatives for use in high‐voltage cable insulation. Although lots of investigations have been conducted into different combinations of PP blends, literature studies on their dielectric performances under elevated‐temperature service remain scarce. Significantly, scientific mechanisms behind changes in dielectric performances of PP blends with respect to thermal aging, particularly in the presence of compatibilization, has yet to be determined. The current work therefore investigates the evolution of structural and dielectric properties in PP/ethylene‐propylene‐diene monomer (EPDM) blend compatibilized with 0–9 wt% of maleic anhydride (MAH) under several thermal aging conditions, namely, unaged, aged at 100°C, and aged at 120°C. The results demonstrate that, although low amounts (up to 5 wt%) of MAH compatibilization improve the breakdown performance of PP/EPDM by 13%, aging otherwise reduces the breakdown strengths of all the PP/EPDM systems by 14%. Structural characterizations reveal that appropriate MAH compatibilization modifies PP/EPDM interactions and lowers conductivity by 55%, but aging negates these positive effects. Changes in the structure and dielectric properties of the PP/EPDM systems with respect to aging are correlated, offering vital insights for developing PP‐based insulation materials in practical high‐voltage cable applications.