Dielectric performance of silica-filled nanocomposites based on miscible (PP/PP-HI) and immiscible (PP/EOC) polymer blends

Xiaozhen He, Paolo Seri, Ilkka Rytöluoto, Rafal Anyszka, Amirhossein Mahtabani, Hadi Naderiallaf, Minna Niittymäki, Eetta Saarimaki, Christelle Mazel, Gabriele Perego, Kari Lahti, Mika Paajanen, Wilma Dierkes, Anke Blume

Research output: Contribution to journalArticleScientificpeer-review

10 Citations (Scopus)
14 Downloads (Pure)


This study compares different polymer-nanofiller blends concerning their suitability for application as insulating thermoplastic composites for High Voltage Direct Current (HVDC) cable application. Two polymer blends, PP/EOC (polypropylene/ethylene-octene copolymer) and PP/PP-HI (polypropylene/ propylene-ethylene copolymer) and their nanocomposites filled with 2 wt.% of fumed silica modified with 3-aminopropyltriethoxysilane were studied. Morphology, thermal stability, crystallization behavior dynamic relaxation, conductivity, charge trap distribution and space charge behavior were studied respectively. The results showed that the comprehensive performance of the PP/PP-HI composite is better than the one of the PP/EOC composite due to better polymer miscibility and flexibility, as well as lower charging current density and space charge accumulation. Nanosilica addition improves the thermal stability and dielectric properties of both polymer blends. The filler acts as nucleating agent increasing the crystallization temperature, but decreasing the degree of crystallinity. Dynamic mechanical analysis results revealed three polymer relaxation transitions: PP glass transition (β), weak crystal reorientation (α1) and melting (α2). The nanosilica introduced deep traps in the polymer blends and suppressed space charge accumulation, but slightly increased the conductivity. A hypothesis for the correlation of charge trap distribution and polymer chain transition peaks is developed: In unfilled PP/EOC and PP/PP-HI matrices, charges are mostly located at the crystalline-amorphous interface, whereas in the filled PP/EOC/silica and PP/PP-HI /silica composites, charges are mostly located at the nanosilica-polymer interface. Overall, the PP/PP-HI (55/45) nanocomposite with 2 wt.% modified silica and 0.3 wt.% of antioxidants making it a promising material for PP based HVDC cable insulation application with a reduced space charge accumulation and good mechanical properties.

Original languageEnglish
Pages (from-to)15847-15859
Number of pages13
JournalIEEE Access
Publication statusPublished - 2021
Publication typeA1 Journal article-refereed


  • charge trap distribution
  • HVDC cable insualtion
  • HVDC transmission
  • Nanocomposites
  • nanosilica
  • Polymers
  • PP/EOC
  • PP/PP-HI
  • Scanning electron microscopy
  • Silicon compounds
  • Space charge
  • space charge accumulation
  • Thermal stability

Publication forum classification

  • Publication forum level 2

ASJC Scopus subject areas

  • General Computer Science
  • General Materials Science
  • General Engineering


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