The cotton plant produces a soft, staple fiber called cotton that grows inside a protective capsule called a boll. Its seeds are protected within the boll by cotton fiber. Essentially, it is a seed fiber. The cotton fiber is known as the king of textile fibers. A soft, breathable textile is made from this fiber by spinning into yarn, and it is the most commonly used textile for clothing. Cotton is classified according to its fineness, staple length, maturity, contamination level, and strength. It is easy for cotton to blend with other fibers, particularly polyester and viscose. A major application of cotton is in clothing as well as in home and furnishing textiles.
The majority of cotton fibers are not processed into technical textiles. In the manufacture of curtains, tents, and tarpaulins, cotton is commonly used. A wide variety of apparel is also made with it, including blouses, shirts, dresses, children’s wear, active wear, separates, swimwear, underwear, suits, jackets, skirts, pants, sweaters, hosiery, and neckwear. There are many home fashion articles made of cotton, including curtains, draperies, bedspreads, sheets, towels, table cloths, table mats, and napkins. There are many industrial applications for this fiber, including ropes, bags, shoes, conveyor belts, filter cloth, and medical supplies. As a result of its strength and absorbency, it makes an excellent choice for medical textiles like bandages and swabs. As it has low thermal conductivity, it is ideal for both summer and winter clothing. During the summer, it protects the skin from heat, and during the winter, it keeps the body warm.
Morphological Diagram of Cotton:
Dry cotton fiber is a single plant cell, which is a flattened tube of collapsed cellulose. Each cotton fiber consists of a concentric layer of fresh cellulose extending from the outside to the inside. Cotton fiber is a single plant cell. Its cross section is oval, compared with the normal hexagonal plant cell. However, cotton morphology is described below:
- Primary cell.
- Secondary cell.
The outermost fiber wall is called the cuticle, and the cuticle layer is separable from the fiber itself and consists of wax and pectin materials. Because of its waxy nature, the cuticle adheres tenaciously to the fiber’s primary wall.
Primary wall fibers are composed mainly of cellulose, which is arranged in a crisscross pattern inside the cuticle, called fibrils. The fibrils are about 20 nm thick and spiral about 700 degrees to the fiber axis. This spiral effect on the fiber’s outer wall makes it more resilient against lateral deformation. It is easy for water to penetrate through these fibrils and it is capable of forming bonds with a variety of chemicals, dyes, cross-linking agents, flame-retardants, and water-repellent agents.
The secondary wall contains the majority of cellulose within the fiber, which is found under primary wall. There are three sub layers in it. There is an outermost layer made up of comparatively thin fibrils oriented helical at a 20-35 degree angle. The spiral direction of the fibrils periodically reverses in this region.
A lumen wall separates the secondary wall from the lumen and appears to be more resistant to certain reagents than secondary wall layers. Lumen is hollow canals that run the length of fibers. During the growth period, it is filled with living protoplasm. When a fiber matures and the boll opens, the protoplasm dries up, and the lumen collapses, leaving a central void, or pore space.
Cellulose is the main component of cotton but oil, wax, protein, pectin and some coloring content are also present as following percentage: