Lyocell Fiber Overview
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Questions and Answers

What method is used in the production of Lyocell fiber?

  • Melt spinning
  • Air spinning
  • Solvent spinning (correct)
  • Wet spinning

    • What is the primary solvent used in producing Lyocell fiber?

  • Methanol
  • N-methylmorpholine-N-oxide (correct)
  • Dimethyl sulfoxide
  • Sodium hydroxide

    • How does Lyocell fiber's absorbency compare to cotton?

  • It is more absorbent than cotton (correct)
  • It cannot absorb moisture
  • It is less absorbent than cotton
  • It has the same absorbency as cotton

    • Which physical property of Lyocell fiber is NOT enhanced compared to viscose fiber?

    <p>Colorfastness</p> Signup and view all the answers

    What is a critical advantage of the NMMO solvent used in Lyocell production?

    <p>It can be recycled within the process</p> Signup and view all the answers

    Which type of wood pulp is commonly used for Lyocell fiber production?

    <p>Eucalyptus and Oak</p> Signup and view all the answers

    Which characteristic makes Lyocell the strongest cellulosic fiber?

    <p>Higher crystalline areas and orientation</p> Signup and view all the answers

    What is the initial step in the production process of Lyocell fiber?

    <p>Shredding and mixing wood pulp with solvent</p> Signup and view all the answers

    What is the primary reason for using NMMO in the Lyocell fiber production process?

    <p>It minimizes environmental impact by allowing solvent recycling.</p> Signup and view all the answers

    Which of the following statements about the production of Lyocell fibers is incorrect?

    <p>Wood pulp is fully penetrated by concentrated acid.</p> Signup and view all the answers

    How does the crimping process affect Lyocell fibers after production?

    <p>It prepares fibers in specific forms for various uses.</p> Signup and view all the answers

    What distinguishes the physical properties of Lyocell fiber from typical viscose fiber?

    <p>Enhanced dimensional stability and softness.</p> Signup and view all the answers

    Which of the following is a significant characteristic of Lyocell fiber in comparison to other cellulosic fibers?

    <p>It demonstrates higher absorbency than cotton.</p> Signup and view all the answers

    What does the term 'fibrillated' refer to in the context of Lyocell fiber?

    <p>Fibers broken down into finer structures.</p> Signup and view all the answers

    What is the main consequence of Lyocell fibers having higher crystalline areas?

    <p>Increased strength both in dry and wet states.</p> Signup and view all the answers

    What does the vacuum heating process in the production of Lyocell fibers primarily achieve?

    <p>It removes volatile substances from the solution.</p> Signup and view all the answers

    Which characteristic of Lyocell fibers contributes to their commercial viability?

    <p>Favorable properties such as softness and stability.</p> Signup and view all the answers

    Study Notes

    Lyocell Fiber

    • Lyocell is a new generation cellulosic fiber
    • Made by solvent spinning (dissolving and spinning without a derivative)
    • Direct solvent N-methylmorpholine-N-oxide (NMMO) for cellulose discovered in 1939
    • Commercial production started in 1988 by Courtaulds
    • Global production is close to 0.1 million tons

    Viscose vs. Lyocell

    • Viscose uses derivatization (NaOH/CS2)
    • Lyocell uses direct dissolution (e.g., NMMO)
    • Viscose uses wet spinning
    • Lyocell uses dry-jet wet spinning

    Chemistry of Lyocell Fiber

    • 1-Alkalization
    • 2-Derivatization
    • 1-Dissolution
    • 2-Spinning and regeneration

    Lyocell Fiber Production

    • Bamboo is the raw material
    • Pulp is created from bamboo
    • NMMO is used to dissolve the pulp
    • Spinning process takes place
    • Fibers are washed and dried
    • Solvent (NMMO) is recovered and recycled
    • Fibers can be made into tow, staple, or filament forms
    • Wood pulp (Eucalyptus, Oak) is mixed with dilute aqueous NMMO
    • Excess water is removed and the solution is heated under vacuum at 90-120°C
    • Spinning solution is filtered
    • Fibers are formed by spinning into an air gap and coagulating in a water/NMMO bath

    Physical Properties

    • Similar to viscose fiber, but exhibits enhanced softness, drapability, and dimensional stability
    • Higher absorbency than cotton (11%) and a quick release property
    • Strongest cellulosic fiber at dry and wet states
    • High crystalline areas and orientation
    • Can be fibrillated or non-fibrillated

    Table 1: Lyocell properties vs. viscose, cotton, and polyester

    • Shows a comparison of dry & wet tenacity, dry & wet elongation for Lyocell, Viscose, Cotton, and Polyester.

    Chemical Properties

    • Has better alkali resistance than viscose
    • Better dyeability than cotton and viscose
    • Susceptible to damage by mildew and silverfish

    End Uses

    • Used in apparel, home textiles, and technical textiles
    • Used in soft, luxurious men's and women's dresses
    • Used in undergarments, hosiery, and sportswear

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    Related Documents

    Module 8 Lyocell Fiber PDF

    Description

    Explore the characteristics, production processes, and chemical composition of lyocell fiber. This quiz also compares lyocell with viscose, highlighting their differences and similarities in manufacturing. Learn about the significant role of bamboo and NMMO in producing this sustainable textile.

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