In recent years, regenerated cellulose fibers (such as viscose, Modal, Tencel) have emerged continuously. They meet people’s needs in a timely manner and partially alleviate the problems of resource scarcity and environmental damage today.
Regenerated cellulose fibers have the dual performance advantages of natural cellulose fibers and synthetic fibers, and are now widely used in textiles on an unprecedented scale.
Today we take a look at the differences between the three most common fibers: viscose, Modal, and Lyocell.
1. Regular Viscose Fiber
Viscose is the full name of viscose fiber. It is a cellulose fiber made from “wood” as raw material, extracted from natural wood cellulose and reshaped fiber molecules.
Preparation Method
Plant cellulose is alkalized to form alkali cellulose, then reacted with carbon disulfide to form cellulose xanthate. The viscous solution obtained by dissolving it in dilute alkali solution is called viscose. Viscose becomes viscose fiber after wet spinning and a series of treatment processes.
The unevenness of the complex forming process of ordinary viscose fiber makes the cross-section of conventional viscose fiber waist-round or irregular, with holes inside and irregular grooves in the longitudinal direction.
Viscose has excellent hygroscopicity and dyeability, but its modulus and strength are low, especially wet strength.
2. Modal Fiber
Modal fiber is the trade name of high wet modulus viscose fiber. The difference between it and ordinary viscose fiber is that Modal fiber improves the shortcomings of low strength and low modulus of ordinary viscose fiber in wet state, and has high strength and modulus even in wet state, so it is often called high wet modulus viscose fiber.
Similar products from different fiber manufacturers have different names, such as Lenzing Modal™, Polynosic, Polynosic fiber, High-tenacity fiber, Humu cotton and Newal.
Preparation Method
The high wet modulus performance is endowed by the special process in the production process.
Different from the general viscose fiber production process:
- Cellulose should have a higher average degree of polymerization (about 450).
- The prepared spinning dope has a higher concentration.
- Prepare the corresponding suitable coagulation bath composition (such as increasing the content of zinc sulfate), reduce the coagulation bath temperature, slow down the forming speed, and help to obtain fibers with dense structure and high crystallinity.
The obtained fiber has a relatively uniform inner and outer layer structure, the skin-core layer structure of the fiber cross-section is not as obvious as that of ordinary viscose fiber, the cross-sectional shape tends to be round or waist-round, and the longitudinal surface is relatively smooth. The fiber has high strength and modulus in wet state, and its excellent hygroscopicity is also suitable for making underwear.
3. Lyocell Fiber
Lyocell fiber is a man-made cellulose fiber made from natural cellulose polymers. Invented by Courtaulds in the UK, it is later produced by Lenzing in Switzerland under the trade name Tencel, and in China, the trade name is “Tencel” which is a homophonic translation.
Preparation Method
Lyocell uses N-methylmorpholine N-oxide (NMMO) aqueous solution as solvent, which can directly dissolve cellulose pulp to obtain spinning solution. Then wet spinning or dry-wet spinning method is adopted, with a certain concentration of NMMO-H2O solution as coagulation bath to form fibers, and then the as-spun fibers are stretched, washed, oiled and dried to obtain a new type of cellulose fiber.
Compared with the conventional viscose fiber production method, the biggest advantage of this spinning method is that NMMO can directly dissolve cellulose pulp, which greatly simplifies the production process of spinning dope, and the recovery rate of NMMO can reach more than 99%, so the production process hardly pollutes the environment.
Lyocell fiber has a completely different morphological structure from ordinary viscose, with uniform cross-sectional structure, round shape, no skin-core layer, smooth longitudinal surface without grooves, better mechanical properties than viscose fiber, good washing dimensional stability (shrinkage rate is only 2%), and high hygroscopicity. It has beautiful luster, soft hand feel, good drapability and excellent flowability.
Differences Between Viscose, Modal and Lyocell
Viscose Fiber
- Good hygroscopicity, meeting the physiological requirements of human skin
- Soft, smooth, breathable fabric, not easy to generate static electricity, UV protection
- Comfortable to wear, easy to dye, bright color and good color fastness after dyeing
- Good spinnability, low wet modulus, high shrinkage rate and easy deformation
- Hard hand feel after washing, poor elasticity and abrasion resistance
Modal Fiber
- Soft and smooth touch, bright color and good color fastness
- The fabric feels particularly smooth, with bright luster and better drapability than cotton, polyester and viscose
- Has the strength and toughness of synthetic fibers, silk-like luster and hand feel
- The fabric is wrinkle-resistant and easy-care, with good water absorption and breathability
- Poor fabric stiffness
Lyocell Fiber
- Has various excellent properties of natural and synthetic fibers
- Natural luster, smooth hand feel, high strength, basically no shrinkage
- Good moisture permeability and breathability, soft, comfortable, smooth and cool
- Good drapability, durable and long-wearing
Application Scope
Viscose Fiber
Can be pure spun or blended with other textile fibers, suitable for making underwear, outerwear and various decorative products. Filament fabrics are light and thin, and can be used to weave bed sheets and decorative fabrics besides clothing.
Modal Fiber
Modal fiber knitwear is mainly used to make underwear, and also used for sportswear, casual wear, shirts, high-end garment fabrics, etc. Blending with other fibers can improve the poor stiffness of pure Modal products.
Lyocell Fiber
Covers all textile fields, and can produce high-quality and high-grade products in cotton, wool, silk, linen-type products, as well as knitting or weaving fields.
