What is a Fiber?
All textiles are made up of fibers. Fibers include natural fibers (cotton, bast and leaf fibers, wool, silk) & synthetic fibers.
General Properties of Fibers：
- High length to diameter ration, fineness and flexibility
- A certain level of strength
- Extensibility and elasticity
- Resistance to chemicals, heat and sunlight
- Ability to be colored
Cotton is the most common natural fibers in our daily life.
China, India, Egypt, Peru, Brazil, the United States are the world’s major cotton producing area.
Yellow River, Yangtze River, south, northwest, northeast are five major cotton-producing regions of China.
Cotton fiber structure
Immature fibers exhibit thin wall structures and a large lumen ,whereas mature fibers have thick walls and a small lumen that may not be continuous ,because the wall close the lumen in some sections. The most outer layer of the cotton fibre is the cuticle covered with waxes and pectins and this surrounds a primary wall, built of cellulose, pectins and proteinic material.
Cotton fiber structure properties
- Cotton fibers are thin long and soft, with a high moisture regain .
- Cotton fiber is a moisture and strong porous material. The internal molecular arrangement is not regular, with a large number of hydrophilic molecular structure inside.
- As the warm cotton fiber is a poor conductor of heat and electricity, thermal conductivity is very low, because of its porous nature of cotton fibers, the advantages of high flexibility, can accumulate large amounts of air between the fibers, the air is hot and electric the bad conductor, so cotton fiber products have good moisture retention, use cotton products make people feel warm.
- Easy to fold — less flexible.
- Large shrinkage —- there is a strong absorbent cotton fiber, when it absorbs moisture so that after the expansion of cotton fiber, cotton yarn caused by reduced deformation.
- Cotton fiber, such as prolonged exposure to daylight, strong reduction will be hard-brittle fibers, such as the case of oxidant, with oxidizing bleach or dye, but also will decrease fiber strength, fiber brittle hair hard.
2. Bast and Leaf fibers
Bast and leaf fibers are plant fibre collected from the phloem or bast surrounding the stem of certain dicotyledonous plants.
The bast fibers include flax, ramie, jute & hemp.
Flax is a bast fiber—a woody fiber obtained from the phloem of plants. It derives from the stalk or stem of Linum suitatssimum. The use of linen in Egypt between 3000and 2500B.C. has been verified. Flax fiber is not so fine as cotton, is longer than cotton. The natural color of flax varies from light ivory to gray. While, the color of cotton fibers vary from almost pure white to a dirty gray.
Flax is a strong fiber. Fabrics of flax are durable and easy to maintain because of the fiber strength. When wet, the fiber is about 20 percent stronger than when dry. The amount of elongation that flax will undergo before breaking is very small. Linen fabrics are prone to crease and wrinkle badly. They are somewhat stiff and posses little resiliency. It is these characteristics, it can be made into sacks and hemp rope, etc.
Hemp is traditionally known as a fiber plant and most historical cultivation of the plant in the United States from the 17th to mid-20th centuries was with fiber use in mind.
Hemp fiber structure:
Wool fibres are roughly oval in cross-section and grow in a more or less wary form with a certain amount of twist. The finer the wool, the more the crimp.
Keratin is a complex protein and is amphoteric in nature. so wool can be dyed with acid or reactive dyes.
Wool Fiber Structure
- Length: 1000-1300 yds (915-1190 m)/cocoon; Max 3000yds (2750m)/cocoon, 1 fiber/cocoon.
- Fineness：2.8-3.9dtex (Bombyx mori)
- Absorbency: 8-9%(High heat of wetting)
- Medium tenacity but higher than wool
- High luster
- high crystallinity and triangular cross-sectional shape.
- Scroop: rustling sound due to an acid treatment that hardens fiber surface.
- Lowest UV light resistance: avoid prolonged exposure to sunshine
In order to prevent silk yarn from breaking up in weaving process, the silk filaments are usually produced in the form of yarn by combining reeled strands from several cocoons together by giving a certain twist to hold them and the gum existing on silk helps to hold the strands together.
The degree of crystallinity of silk is about 65%-70%. The degree of polymerization of silk fibroin is uncertain, with DP of 300 to 3000 having been measured in different solvents.
Silk Fibre Structure
5. Synthetic fibers
Synthetic fibers are created by extruding fiber forming materials through spinnerets into air and water, forming a thread.
Common synthetic fibers include:
- Rayon – artificial silk
- Aramids – known as Nomex, Kevlar and Twaron
- PBI (Polybenzimidazole fiber)
- Lyocell (artificial, not synthetic)
Structure of some popular synthetic fibers
Features of some popular synthetic fibers
- Polyester fiber is now the largest man-made fibre in terms of volume of production.
- The acrylic fibres process a very pleasing, warm and soft handle. Fabrics made from it exhibit a silk-like luster, hand and drape.
- Nylon has a lower specific gravity than other fibres. These properties make them very suitable for stockings, parachute fabrics, shirts, underwear, carpet and reinforcement of rubber in tyres and belts.
- Polyester staple is very commonly blended with cotton or other cellulosic fibres in shirts, blouses, dresses, trousers and sheeting.