Space-charge trapping and conduction in LDPE, HDPE and XLPE

TLDR

Lower mobility and the nature, depth, and density of trap sites explain differences in space‑charge accumulation and thresholds among polyethylene types. The study investigates charge injection, transport, and trapping mechanisms in LDPE, HDPE, and XLPE via charging‑discharging current measurements and space‑charge observations. Charge injection, transport, and trapping were examined using charging‑discharging current measurements and space‑charge observations. LDPE shows higher conductivity and mobility than XLPE and HDPE, while HDPE accumulates more charge and has a higher space‑charge threshold than XLPE, with thresholds for LDPE and HDPE nearly identical.

Abstract

The mechanisms of charge injection, transport and trapping in low-density, high-density and cross-linked polyethylene (LDPE, HDPE and XLPE) are investigated in this paper through charging-discharging current measurements and space-charge observations. The conductivity of LDPE is much larger than that of XLPE and HDPE. The threshold for space-charge accumulation and that for a space-charge-limited current mechanism, coinciding for the same material, are almost identical for LDPE and HDPE, while the threshold of XLPE is higher. However, HDPE accumulates more charge than the other two materials. The depolarization space-charge curves and the conduction current versus field characteristics indicate that the mobility of LDPE is larger than that of XLPE and HDPE, which supports the significant difference in conductivity. The lower mobility, as well as the nature, depth and density of trap sites, can explain the difference in space-charge accumulation and thresholds.