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<p>High-voltage polymeric insulators inevitably degrade under strong electric and thermal fields. Here we quantify how aging‑induced deep‑trap evolution and co‑evolving semicrystalline morphology influence DC breakdown in low‑density polyethylene (LDPE). We couple a bipolar charge transport (BCT) model with a molecular chain displacement (MCD) model to capture space-charge accumulation and electro-mechanical failure. Parameter sweeps within reported aging ranges (deep trap energy <i>E</i><sub>T</sub> up to 1.15 × and trap density <i>N</i><sub>T</sub> up to 2 ×) indicate that deep traps predominantly affect space‑charge accumulation and breakdown. The predicted breakdown strength varies non-monotonically with <i>E</i><sub>T</sub>, spanning 86–151% of the pristine value: a modest increase (<i>E</i><sub>T</sub>/<i>E</i><sub>T0</sub>≈1.05) temporarily raises strength to ~ 151% as early-stage chemi-crystallization stiffens the amorphous network and suppresses de-trapping; further trap deepening and oxidation-driven morphological deterioration intensify space-charge field focusing and accelerate chain displacement, lowering strength to<b> ~ </b>86%<b>.</b> In the model, this interplay is represented through crystallinity-dependent changes in molecular mobility and relaxation time, thereby linking morphology to charge transport kinetics without introducing additional fitting parameters. The framework helps clarify the origin of the observed peak‑then‑drop in strength and offers quantitative guidance for durability-oriented design of HV polymeric insulation under evolving aging conditions.</p>

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Aging-induced trap evolution and breakdown strength in LDPE: numerical modeling approach

  • 期刊论文

  • 发表日期：

    2025年11月22日

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  • MinHee Kim,
  • Se-Hee Lee

摘要

High-voltage polymeric insulators inevitably degrade under strong electric and thermal fields. Here we quantify how aging‑induced deep‑trap evolution and co‑evolving semicrystalline morphology influence DC breakdown in low‑density polyethylene (LDPE). We couple a bipolar charge transport (BCT) model with a molecular chain displacement (MCD) model to capture space-charge accumulation and electro-mechanical failure. Parameter sweeps within reported aging ranges (deep trap energy ET up to 1.15 × and trap density NT up to 2 ×) indicate that deep traps predominantly affect space‑charge accumulation and breakdown. The predicted breakdown strength varies non-monotonically with ET, spanning 86–151% of the pristine value: a modest increase (ET/ET0≈1.05) temporarily raises strength to ~ 151% as early-stage chemi-crystallization stiffens the amorphous network and suppresses de-trapping; further trap deepening and oxidation-driven morphological deterioration intensify space-charge field focusing and accelerate chain displacement, lowering strength to ~ 86%. In the model, this interplay is represented through crystallinity-dependent changes in molecular mobility and relaxation time, thereby linking morphology to charge transport kinetics without introducing additional fitting parameters. The framework helps clarify the origin of the observed peak‑then‑drop in strength and offers quantitative guidance for durability-oriented design of HV polymeric insulation under evolving aging conditions.