{
  "patent_number": "US 3671542",
  "country": "US",
  "title": "How Stephanie Kwolek Invented the Liquid Crystal Solution for Kevlar",
  "original_title": "Optically anisotropic aromatic polyamide dopes",
  "summary": "A 1969 chemical discovery describing a specialized liquid mixture that allows for the creation of incredibly strong, high-performance synthetic fibers.",
  "what_it_does": "The patent describes a chemical solution, or dope, containing specific aromatic polyamides that exhibit optical anisotropy. This means the molecules in the liquid align themselves in a structured, orderly way rather than floating randomly. When this liquid is spun into fibers, that internal order is preserved, resulting in a material with extreme tensile strength and stiffness. The patent specifically details using concentrated sulfuric acid as the solvent to achieve this unique molecular alignment.",
  "what_it_does_not_cover": [
    "Does not cover the final solid fiber product itself, only the liquid dope composition.",
    "Does not cover standard polymers that do not exhibit optical anisotropy in solution.",
    "Does not cover spinning processes or mechanical equipment used to create the fibers."
  ],
  "filed": "1969-05-23",
  "granted": "1972-06-20",
  "expires": "1989-06-20",
  "status": "expired",
  "holder": "EI Du Pont de Nemours and Co",
  "holder_url": "https://patentbrief.org/company/ei-du-pont-de-nemours-and-co",
  "inventors": [
    {
      "name": "Stephanie Louise Kwolek",
      "url": "https://patentbrief.org/inventor/stephanie-louise-kwolek"
    }
  ],
  "times_cited": 132,
  "tags": [
    "materials",
    "mechanical",
    "chemical"
  ],
  "abstract": "Compositions or dopes comprising carbocyclic aromatic polyamides in suitable liquid media are prepared which are optically anisotropic (exhibit different light transmission properties in different directions in the dope). These dopes, and related isotropic dopes, are used in preparing fibers of unique internal structure (evidenced by low orientation angle and/or high sonic velocity) and exceptionally high tensile properties (e.g., initial modulus).",
  "url": "https://patentbrief.org/patent/us/3671542/kevlar-aramid-fiber",
  "markdown_url": "https://patentbrief.org/patent/us/3671542/kevlar-aramid-fiber/md",
  "google_patents_url": "https://patents.google.com/patent/US3671542",
  "relatedPatents": [
    {
      "patentNumber": "3819587",
      "countryCode": "US",
      "title": "The Molecular Structure of Kevlar High-Strength Fiber",
      "url": "https://patentbrief.org/patent/us/3819587/kevlar-aramid-fiber-kwolek"
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}