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 (D)</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 (C)</p> Signup and view all the answers

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

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

Which characteristic makes Lyocell the strongest cellulosic fiber?

<p>Higher crystalline areas and orientation (D)</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 (C)</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. (A)</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. (C)</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. (B)</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. (B)</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. (D)</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. (C)</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. (B)</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. (B)</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. (A)</p> Signup and view all the answers

Flashcards

Lyocell Fiber

A new generation cellulosic fiber made through solvent spinning, dissolving and spinning cellulose without creating a derivative.

Solvent Spinning

A fiber production method that dissolves and spins a material, such as cellulose, without creating a new derivative, like a chemical change.

NMMO

N-methylmorpholine-N-oxide, a solvent used in lyocell fiber production.

Lyocell Production Process

Wood pulp is mixed with NMMO, water is removed, heated under vacuum, filtered, spun into fibers, and washed.

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Lyocell Physical Properties

Similar to viscose fibers, but softer, more drapable, and dimensionally stable. High absorbency compared to cotton.

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Lyocell Strength

The strongest cellulosic fiber, both wet and dry.

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Fiber Formation

Lyocell fibers are formed by spinning into an air gap and coagulating in a water/NMMO bath.

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Lyocell Fiber Forms

Lyocell fibers can be produced as tow, staple, or filament.

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What is Lyocell?

A new type of cellulosic fiber made by dissolving and spinning cellulose without creating a derivative.

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How is Lyocell made?

It's produced through solvent spinning, using NMMO to dissolve wood pulp. The solution is then spun into fibers.

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What is NMMO?

N-methylmorpholine-N-oxide, a non-toxic solvent used to dissolve cellulose in Lyocell production.

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Production Process: Steps 1 & 2

  1. Shredded wood pulp is mixed with dilute NMMO to penetrate the pulp.
  2. Excess water is removed and the solution is heated under vacuum.
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Production Process: Steps 3 & 4

  1. The solution is filtered to remove any impurities.
  2. Fibers are formed by spinning the solution into an air gap and then coagulating in a water/NMMO bath.
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Production Process: Steps 5 & 6

  1. The fibers are washed and dried.
  2. The wash liquor is purified and concentrated to recover the NMMO solvent.
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Lyocell vs. Viscose

Lyocell is similar to viscose, but stronger, softer, more drapable, and has better dimensional stability.

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Lyocell Absorbency

Lyocell has higher absorbency than cotton (moisture regain is around 11%) and releases moisture quickly.

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Lyocell Crystalline Structure

Lyocell fibers have higher crystalline areas and orientation, contributing to its strength.

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Lyocell Forms

Lyocell fibers can be produced as tow (bundles), staple (short fibers), or filament (continuous long fibers).

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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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