{
  "abstract": "Thin-profile broadband microwave absorbers must reconcile impedance matching and strong attenuation, two requirements that usually pull in opposite directions. Here, hollow carbonized kapok fibers (CKFs) obtained at 1000 °C were compounded with waterborne polyurethane (WPU) at a mass ratio of 8:2 and consolidated by hot pressing. The film reached a dielectric real part of about 325 and behaved as a frequency-selective layer: it transmitted low-frequency microwaves while reflecting high-frequency ones, governed by the frequency-dependent permittivity, the skin effect, a narrow resonance window, mesopore scattering, and the impedance mismatch with free space. Inserting a 0.62 mm CKF/WPU interlayer between a high-frequency surface layer and a low-frequency bottom layer broadened the effective absorption bandwidth from 4.71 to 9.27 GHz (windows at 3.33–9.30 and 11.6–14.9 GHz), with a minimum reflection loss of −54.8 dB at a total thickness of only 1.53–1.62 mm, covering the whole C band and parts of the S and X bands. This provides a low-cost route to thin, flexible multiband microwave absorbers through a biomass-derived filtering interlayer.",
  "abstract_shown": true,
  "affiliations": [
    "School of Art and Media, Quanzhou Vocational and Technical University, Quanzhou 362268, China",
    "School of Textile Science and Engineering, Tiangong University, Tianjin 300387, China",
    "Ministry of Education Key Laboratory for Advanced Textile Composite Materials, Tiangong University, Tianjin 300387, China"
  ],
  "article_type": null,
  "arxiv": null,
  "author_total": 4,
  "authors": [
    {
      "affs": [
        0,
        1
      ],
      "name": "Aiqiong Wang"
    },
    {
      "affs": [
        0
      ],
      "name": "Yichen Lin"
    },
    {
      "affs": [
        1,
        2
      ],
      "name": "Zhenrong Zheng"
    },
    {
      "affs": [
        1,
        2
      ],
      "name": "Xiaoming Zhao"
    }
  ],
  "bibtex": "https://research.draconitic.com/paper/djbwtx9mjhn8p.bib",
  "cited_by": 0,
  "doi": "10.3390/molecules31213985",
  "fulltext_url": null,
  "id": "djbwtx9mjhn8p",
  "issns": [
    "1420-3049"
  ],
  "landing_url": "https://www.mdpi.com/1420-3049/31/21/3985",
  "language": null,
  "licence": "CC-BY-4.0",
  "licence_label": "CC BY 4.0",
  "licence_source": "article",
  "licence_url": "https://creativecommons.org/licenses/by/4.0/",
  "metadata_licence": null,
  "native_subjects": [],
  "openalex": null,
  "pdf_url": null,
  "pmcid": null,
  "pmid": null,
  "published": "2026-11-05",
  "publisher": "MDPI AG",
  "ris": "https://research.draconitic.com/paper/djbwtx9mjhn8p.ris",
  "sources": [
    {
      "first_seen": "2026-11-05T12:20:54Z",
      "native_id": "10.3390/molecules31213985",
      "source": "crossref",
      "url": "https://www.mdpi.com/1420-3049/31/21/3985"
    }
  ],
  "subjects": [
    {
      "field": "chemistry",
      "origin": "issn:1420-3049",
      "subfield": "general"
    }
  ],
  "title": "High-Permittivity Carbonized Kapok Fiber/Waterborne Polyurethane Composite Films as Frequency-Selective Filtering Layers for Thin-Profile Multiband Microwave Absorption",
  "title_text": "High-Permittivity Carbonized Kapok Fiber/Waterborne Polyurethane Composite Films as Frequency-Selective Filtering Layers for Thin-Profile Multiband Microwave Absorption",
  "type": "peer-reviewed",
  "updated_at": "2026-11-07T00:21:07Z",
  "url": "https://research.draconitic.com/paper/djbwtx9mjhn8p",
  "venue": "Molecules",
  "versions": []
}