On the temperature dependence of electrical and mechanical properties of recyclable cable insulation materials based upon polyethylene blends

Crosslinked polyethylene (XLPE) has been used as cable insulation since the 1960s, due to its favourable combination of electrical and mechanical properties. However, a fundamental consequence of crosslinking is limited recyclability. Although technologies are being developed to facilitate the re-use of XLPE at the end of its service life, such approaches are inferior to a fully recyclable alternative. In this paper, we report on the use of binary blends of linear (LPE) and branched (BPE) polyethylenes as possible replacement materials for XLPE, since such systems have the potential to combine comparable mechanical properties and enhanced breakdown strength with recyclability. Specifically, we consider the thin film AC ramp breakdown behaviour as a function of temperature up to 90 °C; the behaviour of a non-isothermally crystallized blend is contrasted with that of the constituent BPE in virgin and crosslinked states. These data are augmented with dynamic mechanical thermal analysis. In concert, these data indicate that, with appropriate morphological control, the blended thermoplastic material can exhibits superior properties to XLPE within the temperature range studied.