Ultra-high molecular weight polyethylene nanocomposites for enhanced dielectric, thermal, and mechanical performance in polypropylene ‒ advancing towards a more sustainable high voltage power grid

Abstract

This work reports on the effects of ultra-high molecular weight polyethylene (UHMWPE) nanocomposites, with the main objective of advancing the development of novel high voltage (HV) insulation cables using polypropylene (PP)-based materials for enhanced dielectric, thermal, and mechanical performance. Surface functionalisation of titanium dioxide (TiO2) and magnesium oxide (MgO) nanofillers with polar silane coupling agents (SCA) is implemented using the anhydrous technique. Nanocomposites are prepared using a solution blending method.Dielectric bulk properties, specifically the dielectric relaxation peak frequencies, are attributed to the water bonding states, which result from differences in the polarities of surface functional groups, rather than the bulk properties of the nanoparticles. Similar to charge transport, varying polarities of SCA result in different bonding states with water molecules. This, in turn, influences energy band levels at interfaces and affects the movement of charge carriers in the bulk materials. While the thermal conductivity in nanocomposites mainly results from the long molecular chains of UHMWPE rather than the high intrinsic thermal conductivity of nanofillers, the enhanced interfacial interaction between PP and UHMWPE, achieved by using nanoparticles as a compatibiliser, results in improved mechanical elasticity and elongation at break. Furthermore, this improved interfacial interaction is directly linked to enhanced dielectric performance in polymer blends and polymer nanocomposites, either through the heterogeneity of surface nucleation at the interfaces of PP/UHMWPE blends or by enhancing the interfacial interaction between two polymers using nanoparticles.
In addition, the presence of nanoparticles as a compatibiliser between two immiscible polymer blends delays thermo-oxidative reactions and structural changes during thermal ageing. This results in nanocomposites having a better ability to retain dielectric performance after thermal ageing than the unfilled blends. Overall, this study establishes the relationship between enhanced dielectric, thermal, and mechanical performance, and the physical and chemical characteristics in PP-based UHMWPE nanocomposites. The findings highlight the potential of these UHMWPE nanocomposites in a PP matrix as insulation materials for HV cables, contributing to a more sustainable HV power grid.

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Identifiers

ORCID for Phichet Ketsamee: orcid.org/0000-0003-1733-6806

ORCID for Thomas Andritsch: orcid.org/0000-0002-3462-022X

ORCID for Alun Vaughan: orcid.org/0000-0002-0535-513X

ORCID for Istebreq Saeedi: orcid.org/0000-0002-1254-748X

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