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Atomistic-scale insight into the polyethylene electrical breakdown: An eReaxFF molecular dynamics study

Summary

Cross-linked polyethylene (XLPE) is a common high-voltage insulator; residual by-products from peroxide curing may alter dielectric reliability. This study uses an eReaxFF-based MD framework—explicit electrons included and verified against DFT—to relate mass density, void content, and acetophenone-class additives to time-dependent dielectric breakdown (TDDB). eReaxFF MD with explicit electronic variables probes how XLPE by-products (e.g. acetophenone), packing density, and void connectivity steer failure times. Simulations report that higher PE density increases TDDB, whereas additives with positive electron affinity such as acetophenone can shorten TDDB. During breakdown, electrons preferentially traverse voids between electrodes. The acetophenone radical anion markedly reduces reaction barriers and exothermicities of secondary reactions compared with neutral acetophenone, which the authors connect to accelerated chemical damage pathways alongside electronic transport.

Methods

  • Not stated in this wiki note: the prior draft did not isolate force-field training text here; see §B–C and the primary PDF for ReaxFF lineage, training sets, and QM references used in fitting.

B — Molecular dynamics, experiments, protocols, and sampling

Systems: Polyethylene models spanning density and void distributions; acetophenone and derived radical anion chemistries as stated in the article, with microstructures chosen to mimic void channels between electrodes.

MD: eReaxFF reactive MD with inter-electrode electric field / bias protocols for TDDB; N/A here to paste full LAMMPS input—see JCP/pdf_path for 3D PBC PE supercells (stoichiometry and atom count per case), NVT/NVE (and NPT/1 bar isotropic pressure control if used), fs timestep, K temperature setpoints, ps/ns duration, Nose–Hoover-class thermostat, and how breakdown events are detected. Umbrella / metadynamics—N/A unless SI states otherwise.

C — Electronic structure / static QM (when reported separately from MD)

Model: eReaxFF (extended ReaxFF class treating electronic degrees of freedom within the parametrization used here) with DFT validation for key electron attachment and reaction energetics, including checks on species relevant to peroxide-cure residuals.

D — Review scope, SI/galley notes, and non-primary corpus roles

  • Not applicable: primary research article unless the Summary flags a review, SI-only register, or duplicate PDF (see Reader notes / Limitations).

Findings

Density and void microstructure strongly modulate breakdown times. By-product species with favorable electron affinity can accelerate failure. Void-connected paths dominate inter-electrode electron migration in the modeled breakdown scenarios. Radical anions shift secondary reaction kinetics relative to neutral precursors, supporting a picture in which both electronic pathway availability and follow-on bond-making chemistry control TDDB trends. Comparisons in the JCP text pair eReaxFF with DFT for key energetics. Sensitivity of TDDB to density, voids, and additives (e.g. acetophenone) is a main theme. Limitations on engineering extrapolation are authored in the article and below; citable values and protocol tables must be taken from the VOR pdf_path (this page is a corpus summary only).

Limitations

eReaxFF approximates electronic effects; quantitative TDDB lifetimes must be mapped carefully to engineering voltage/temperature conditions. Finite cells and short segments capture initiation chemistry more reliably than full device-scale breakdown statistics, so extrapolation to AC waveforms or broad temperature ramps should be treated as qualitative guidance pending targeted validation against experiment or higher-level electronic-structure methods on representative fragments. For peer-reviewed pagination and figure labels, prefer the JCP online PDF referenced in the bibliography rather than any local proof artifacts if both appear in a workspace.

Relevance to group

Demonstrates eReaxFF for dielectric breakdown in hydrocarbon polymers with industrial (cable) relevance.

Citations and evidence anchors

Reader notes (navigation)