Regenerated Fibre

 Regenerated cellulosic fibres | Types of regenerated fibres

Regenerated cellulosic fibers are a type of fiber derived from natural sources such as wood pulp or cotton linters. These fibers are processed through chemical treatments to dissolve the cellulose, which is then extruded to form fibers. Common types of regenerated cellulosic fibers include viscose rayon, lyocell (branded as Tencel), and modal.

Viscose Rayon: This was the first commercialized regenerated cellulosic fiber. It is made from wood pulp and has a soft feel, good drape, and breathability. However, it has drawbacks such as environmental concerns related to its production process.

Lyocell (Tencel): Lyocell is a newer type of regenerated cellulose fiber known for its eco-friendly production process. It is made from wood pulp using a closed-loop system where the chemicals used in processing are recycled. Lyocell fibers are known for their softness, strength, and moisture absorption.

Modal: Modal is another type of regenerated cellulosic fiber made from beech trees. It is similar to viscose rayon but is processed in a way that gives it higher strength and durability. Modal fibers are often used in clothing where a silky feel and good drape are desired.

Regenerated cellulosic fibers are popular in the textile industry due to their natural origins and desirable properties. However, their production processes can have environmental impacts, particularly in terms of chemical use and waste disposal. Efforts are ongoing to improve the sustainability of these fibers through better manufacturing practices and recycling technologies.

Regenerated fibres examples

Regenerated fibers, also known as semi-synthetic fibers, are created from natural raw materials that are chemically processed to produce fibers with specific properties. The most common regenerated fibers are rayon, modal, lyocell, and acetate. Here’s a comprehensive overview of the properties of regenerated fibers:
1. Composition and Structure
  • Rayon: Made from regenerated cellulose obtained from wood pulp or cotton linters. It includes viscose rayon, modal, and lyocell.
  • Modal: A type of rayon that is made from beech tree wood pulp. It is more refined and often considered a higher-quality form of rayon.
  • Lyocell: Also known as Tencel, it is made from cellulose derived from wood pulp using a closed-loop process that recycles water and solvents.
  • Acetate: Made from cellulose acetate, which is created by chemically modifying cellulose from wood pulp.
2. Physical Properties
  • Softness and Smoothness: Regenerated fibers like rayon and modal are known for their softness and smooth texture, often used in garments where comfort is a priority.
  • Luster: These fibers can have a shiny appearance, especially acetate and some types of rayon, which can be manipulated to produce a glossy finish.
  • Drape and Flow: Regenerated fibers generally have a good drape, making them ideal for garments like dresses and skirts that require a flowy, elegant look.
3. Absorbency and Moisture Management
  • High Absorbency: Rayon, modal, and lyocell are highly absorbent fibers, which means they can wick moisture away from the skin, making them suitable for summer wear and activewear.
  • Breathability: These fibers are breathable and can help keep the wearer cool and dry.
4. Durability
  • Wear and Tear: Regenerated fibers tend to be less durable compared to synthetic fibers like polyester. Rayon and acetate can wear out more quickly and may be prone to stretching and breaking.
  • Strength: While lyocell is generally stronger and more durable than rayon and acetate, rayon and acetate fibers are relatively weak when wet.
5. Care and Maintenance
  • Washing: Regenerated fibers often require gentle washing and may be prone to shrinking or losing shape if not properly cared for. Lyocell is more resistant to shrinkage compared to rayon and acetate.
  • Drying: It is often recommended to air dry garments made from these fibers to prevent damage from high heat.
6. Environmental Impact
  • Sustainability: The environmental impact varies by type:
    • Rayon: Traditional rayon production can be polluting due to chemical processes. However, some newer forms of rayon are more eco-friendly.
    • Modal and Lyocell: These fibers are produced with more sustainable methods. Lyocell uses a closed-loop process that reuses chemicals and solvents.
    • Acetate: The production process for acetate involves toxic chemicals, but some companies are working to make it more sustainable.
7. Comfort and Wearability
  • Comfort: Regenerated fibers are generally comfortable and have a luxurious feel against the skin.
  • Skin Sensitivity: They are usually hypoallergenic and less likely to irritate sensitive skin compared to some synthetic fibers.
8. Color and Dyeing
  • Color Retention: Regenerated fibers take dye well and retain color effectively, which allows for a wide range of vibrant and lasting colors.
  • Dyeing Techniques: They can be dyed using various techniques, and the dyeing process is typically straightforward.
9. Thermal Properties
  • Temperature Regulation: They are not as insulating as wool or other thermal fibers, so they are not ideal for very cold weather. However, they can be comfortable in moderate temperatures due to their breathability.
10. Elasticity
  • Stretch and Recovery: Regenerated fibers typically have limited elasticity. They do not stretch or recover well compared to fibers like spandex, so garments may lose their shape over time.

Frequently asked questions | FAQs

Why rayon is called regenerated fibres?

Rayon is primarily made from natural cellulose. Cellulose is a major component of plant cell walls, and it is sourced from wood pulp, cotton linters, or other plant materials.
Chemical processing::
Dissolution: The cellulose is first dissolved in a chemical solution, such as sodium hydroxide (lye) to create a viscous solution. This process breaks down the cellulose into a soluble form.
Regeneration: The dissolved cellulose is then regenerated into fiber form through a chemical process. For rayon, this typically involves dissolving the cellulose in a viscous solution and then extruding it through spinnerets to form fibers. In the case of viscose rayon, the process involves:Cellulose is treated with sodium hydroxide to form alkali cellulose.
The alkali cellulose is then treated with carbon disulfide to produce cellulose xanthate.
This solution is dissolved in a dilute solution of sodium hydroxide to form viscose.
The viscose solution is then forced through spinnerets into a bath of sulfuric acid to regenerate the cellulose into rayon fibers.
Formation of the Fiber:
The regenerated cellulose is then spun into fibers, which are spun into yarns or used to make fabrics. The fibers have a structure that resembles natural cellulose, but the regeneration process alters the properties of the material compared to its raw source.

The Regeneration Process
Here’s a step-by-step breakdown of how rayon is regenerated from natural cellulose:
Cellulose Extraction
Natural cellulose is extracted from wood or cotton.
To obtain the raw material for regeneration.
Alkalization
Cellulose is treated with sodium hydroxide.
To convert cellulose into alkali cellulose.
Xanthation
Alkali cellulose is treated with carbon disulfide.
To produce cellulose xanthate.
Dissolution
Cellulose xanthate is dissolved in a dilute sodium hydroxide solution.
To create a viscous solution called viscose.
Spinning
Viscose is extruded through spinnerets into a coagulation bath.
To regenerate cellulose into fibers.
Washing and Bleaching
The fibers are washed and bleached.
To remove any residual chemicals and improve fiber quality.

What is the difference between regenerated and synthetic fibres?

Regenerated and synthetic fibers are two main categories of man-made fibers used in textiles, but they are created from different raw materials and processes. Here’s a detailed comparison highlighting the differences between regenerated and synthetic fibers:
Source of Raw Materials
Raw Materials
Regenerated Fibers
Derived from natural sources, primarily cellulose from wood or cotton.
Synthetic Fibers
Made from petrochemicals or other synthetic polymers.
Examples
Regenerated Fibers
Rayon, Modal, Lyocell, Acetate
Synthetic Fibers
Polyester, Nylon, Spandex, Acrylic
Base Material
Regenerated Fibers
Natural cellulose fibers (wood pulp, cotton linters)
Synthetic Fibers
Chemical compounds like petroleum products or natural gas
2. Production Processes
Processing
Regenerated Fibers
Cellulose Regeneration: Natural cellulose is dissolved and then regenerated into fibers.
Synthetic Fibers
Polymerization: Chemical processes create polymers from raw chemicals, which are then spun into fibers.
Examples of Processes
Regenerated Fibers
Viscose process, Modal process, Lyocell process, Acetate process
Synthetic Fibers
Melt spinning, Dry spinning, Wet spinning
Regenerated Fiber Production Steps:
Extraction of Cellulose: Sourced from natural plants (wood pulp or cotton).
Dissolution: Cellulose is chemically dissolved to form a viscous solution.
Regeneration: The solution is regenerated into fibers through various chemical processes.
Spinning: The fibers are spun into yarns or fabrics.
Synthetic Fiber Production Steps:
Polymer Creation: Monomers are polymerized to form synthetic polymers.
Fiber Formation: Polymers are melted or dissolved and spun into fibers.
Spinning: The fibers are extruded through spinnerets and formed into yarns or fabrics.Regenerated FibersRegenerated and synthetic fibers are two main categories of man-made fibers used in textiles, but they are created from different raw materials and processes. Here’s a detailed comparison highlighting the differences between regenerated and synthetic fibers: