PA

Fibers and Yarn Numbering

Elastomeric Fibers

  • Definition: Elastomeric fibers are created from an elastomer consisting of at least 85% by mass of segmented polyurethane.
  • Characteristics:
    • Fibers can stretch under a traction force to three times their initial length.
    • They quickly return to their original length once the tension is removed.
  • Historical Context:
    • First launched in 1959 by a leading American manufacturer, which remains the largest producer today.
  • Usage: These fibers are typically not used independently but rather to support other fibers, enhancing the elasticity of various fabrics.
  • Common Applications:
    • Swimwear
    • Hosiery
    • Sportswear
    • Knitwear
    • Corsetry
    • Underwear
    • Lingerie

Mineral Fibers (Inorganic)

  • Types: Mineral fibers can be divided into metallic and non-metallic categories.
  • Properties:
    • Durable and rigid in nature.
    • Have a higher melting point compared to traditional fibers.
    • Excellent resistance to heat and completely non-flammable (except for metallic fibers).
    • Generally considered fragile.
  • Performance:
    • Superior functioning in high temperatures and corrosive environments.
  • Forms: Common presentations include padding, mats, and felts.
  • Continuous fibers can be manufactured using the spinning process for materials that are meltable (e.g., glass, mineral fibers).

Yarn Numbering

  • Definition: Yarn numbering is the classification process that determines the fineness of a thread or yarn. This is crucial since the cross-section of a fiber is often deformable and not easily measurable.
  • Ratio Definition:
    • Yarn numbering is expressed as a ratio between the length and weight of the yarn.
  • Systems of Yarn Numbering:
    • Direct System: Describes the ratio between weight and length.
    • Formula: T = P/L (where T = yarn number, P = weight, L = length)
    • Commonly applied to continuous fibers such as silk, rayon, nylon, etc.
    • Notable Direct Systems:
      • Tex
      • Decitex
      • Denier
    • Key Characteristic: In direct systems, a finer yarn corresponds to a smaller number.
    • Indirect System: Describes the ratio between length and weight.
    • Formula: N = L/P (where N = yarn number, L = length, P = weight)
    • Typically used for natural fibers such as wool and cotton.
    • Notable Indirect Systems:
      • Metric titration
      • Kilogrammetrica
      • Yarn Numbering-English cotton
      • Yarn Numbering of Prato
    • Key Characteristic: In indirect systems, a higher number corresponds to a finer yarn.