{
  "abstract": "Polyamide 6 and 66 (PA6/PA66) are the only commodity plastics with structural nitrogen (12.4 wt%), yet chemical recycling frameworks treat nitrogen fate as an uncontrolled byproduct. We extend Reaction Network Flux Analysis (RNFA) to a full C-H-O-N mass balance and introduce two new metrics—Nitrogen Atom Economy (NAE) and Nitrogen Footprint (NF)—enabling the first systematic nitrogen-centric optimisation of PA6/PA66 depolymerization. Across 795 NLP solves (GAMS/BARON) spanning six products, five depolymerization route families, and five objective weight scenarios, three findings emerge. First, nitrogen-centric optimisation achieves NAE = 87–100% across all products, compared with the conventional unoptimised baseline of ∼60%. Second, carbon-only objective functions generate NF 6–62× higher than nitrogen-inclusive weighting; for caprolactam and 6-ACA, two economically identical routes differ by up to 62× in nitrogen footprint. Any objective weight w2 ≥ 0.3 on the nitrogen term recovers >90% of the achievable NF reduction. Third, for five of six products, the nitrogen-optimal configuration is simultane- ously the economic optimum—no cost penalty is incurred. These results support a seventh guiding principle for nitrogen-containing polymer upcycling: maximise nitrogen circularity, extending the six-principle framework of Jehanno et al. beyond carbon-centric assessment to address the planetary nitrogen boundary, currently transgressed by a factor of ∼2.4.",
  "abstract_shown": true,
  "affiliations": [
    "Aachener Verfahrenstechnik (AVT.PT)",
    "RWTH Aachen University"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 1,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Huiting Yang"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/3e5etbze64btb.bib",
  "cited_by": 0,
  "doi": "10.26434/chemrxiv.15008194/v1",
  "fulltext_url": null,
  "id": "3e5etbze64btb",
  "issns": [],
  "landing_url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008194/v1",
  "language": null,
  "licence": "CC-BY",
  "licence_label": "CC BY",
  "licence_source": "journal",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [
    [
      "openalex",
      "2507|Polymer crystallization and properties"
    ]
  ],
  "openalex": "W7205006099",
  "pdf_url": "https://chemrxiv.org/doi/pdf/10.26434/chemrxiv.15008194/v1",
  "pmcid": null,
  "pmid": null,
  "published": "2026-09-02",
  "publisher": "American Chemical Society (ACS)",
  "ris": "https://research.draconitic.com/paper/3e5etbze64btb.ris",
  "sources": [
    {
      "first_seen": "2026-10-30T12:17:17Z",
      "native_id": "10.26434/chemrxiv.15008194",
      "source": "chemrxiv",
      "url": "https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008194/v1"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "openalex:2507|Polymer crystallization and properties",
      "subfield": "materials-polymers"
    }
  ],
  "title": "Nitrogen-Centric Optimization of Polyamide Chemical Recycling: A Reaction Network Flux Analysis with New Metrics for Nitrogen Atom Economy and Nitrogen Footprint",
  "title_text": "Nitrogen-Centric Optimization of Polyamide Chemical Recycling: A Reaction Network Flux Analysis with New Metrics for Nitrogen Atom Economy and Nitrogen Footprint",
  "type": "preprint",
  "updated_at": "2026-10-30T12:17:17Z",
  "url": "https://research.draconitic.com/paper/3e5etbze64btb",
  "venue": "ChemRxiv",
  "versions": []
}