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Atomistic-scale insights into the crosslinking of polyethylene induced by peroxides (uncorrected proof PDF)

Summary

ReaxFF MD plus FTIR mapping and WAXS probe peroxide-induced cross-linking of polyethylene relevant to HV cable XLPE. The study focuses on dicumyl peroxide (DCP) chemistry, byproduct formation, and how temperature, density, DCP loading, electric field, and alternative peroxides modulate cross-link yield. Cable insulation reliability depends on uniform cure and low void content; atomistic models here isolate how peroxide fragmentation and radical recombination channels compete before continuum processing maps are attempted.

Methods

  • Reactive MD: ReaxFF simulations of PE with peroxide curing agents under varied thermal and density conditions (abstract).
  • Experiments: FTIR spatial mapping and WAXS to corroborate cross-linking extent and phase features (abstract).
  • Sweeps: Curing temperature (noting ~500 K as a practical optimum in abstract before over-curing), system density, DCP:PE ratio, applied electric field, and comparison of DCP vs di-(1-decyl-1-phenylundecyl) peroxide efficiency (abstract).
  • Spatial FTIR interpretation ties carbonyl and unsaturation signatures to under-cured versus over-cured regions when available in the article figures.

MD application. ReaxFF molecular dynamics in LAMMPS on 3D PBC polyethylene/peroxide supercells with atom/stoichiometry details on [[2019akbarian-polymer-183-atomistic-scale-insights]]. NVT protocol: 2.25 ns equilibration, 0.25 fs timestep, Berendsen thermostat (100 fs damping). Barostat / pressure: N/A — these NVT state-point runs are constant-volume sampling without a NPT barostat (no independent hydrostatic pressure control in the quoted NVT equilibration blocks). The uncorrected proof here is for line-numbered QA; copy integrator settings from the VOR PDF for external citations.

Findings

  • Temperature: Raising cure temperature toward ~500 K increases cross-linking, but >500 K can hurt cross-link quality (abstract).
  • Density: Higher density promotes cross-linking (abstract).
  • DCP stoichiometry: Large DCP excess raises byproducts without necessarily increasing XLPE yield (abstract).
  • Field: Simulations report negligible influence of an external electric field on cross-linking under their protocol (abstract).
  • Peroxide choice: The alternative peroxide explored is less efficient than DCP for XLPE in their comparison (abstract).
  • Byproduct channels are highlighted where excess initiator drives scission or oxidation side chemistry that does not contribute to gel fraction gains.

Limitations

Uncorrected proof PDF—prefer [[2019akbarian-polymer-183-atomistic-scale-insights]] for the version-of-record path when available. Industrial XLPE recipes contain many additives not modeled atomistically here.

Curation note: the Elsevier proof may interleave queries; do not treat placeholder pages as final pagination for external citations—use the VOR sibling above when possible. FTIR maps in the article are the primary experimental anchor for spatial heterogeneity in cure quality. WAXS traces supplement FTIR by indicating crystallinity changes when cross-links pin chains differently across temperature ramps. DCP stoichiometry sweeps in the abstract bracket practical cable recipe windows without claiming industrial batch reproducibility.

Relevance to group

Integrates ReaxFF polymer chemistry with industrial (Dow) analytics for dielectric materials aligned with power cable research.

Citations and evidence anchors

Reader notes (navigation)