Cotton Fiber | Cross section of Cotton | Properties of Cotton Fiber

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Cotton is a natural cellulosic fiber with a soft handle. The raw cotton contains almost 85 to 90 percent cellulose in its composition. This fluffy staple fiber grows in a bowl or protective capsule. Cotton plants are under the genus Gossypium. In the present world the most important, widespread and inexpensive textile fiber is cotton, a strong, thin and hygroscopic fiber. It develops on the seeds of the cotton plant. Today it is the most used textile fiber in the world. Its current market share is 56 percent among all the textile fibers. It is used for apparel and home furnishing materials and another contribution is attributed to non-woven textiles and personal care items. Compare to other fibers, it is recognized as the most consumers prefer fiber.

Cross Sectional View of Cotton Fiber

Under a cross sectional view of cotton it is composed of concentric layers. Cotton has a distinct cuticle, well developed primary and secondary cell walls as well as a lumen. The cuticle layer on the fiber itself is separable from the fiber and consists of wax and pectin materials. The primary wall, the most peripheral layer of the fiber, is composed of cellulosic crystalline fibrils. The secondary wall of the fiber consists of three distinct layers. All three layers of the secondary wall include closely packed parallel fibrils with spiral winding of 25-35o and represent the majority of cellulose within the fiber. The innermost part of a cotton fiber, the lumen- is composed of the remains of the cell contents.

Chemical Composition of Cotton

Component	Percentage
Cellulose	85.5%
Water/Moisture	8%
Protein	1.3%
Hemicelluloses & Pectin	1.2%
Waxes and fats	0.6%
Ash	1.2%
Pigments and Others	1.4%
Total	About 100%

Chemical structure and repeating unit:

After removing all the impurities and natural color material from cotton, it contains 99% cellulose. Cellulose is a macromolecule –– a polymer made up of a long chain of glucose molecules linked by C-1 to C-4 oxygen bridges with elimination of water (glycoside bonds). The anhydroglucose units are linked together as beta-cellobiose; therefore, anhydro-beta-cellobiose is the repeating unit of the polymer chain. The number of repeat units linked together to form the cellulose polymer is referred to as the “degree of polymerization.”

Wood pulp, rayon and cellophane (all three derived from wood cellulose) are also constructed of cellulose polymers. Cotton cellulose differs from wood cellulose primarily by having a higher degree of polymerization and crystallinity. Crystallinity indicates that the fiber molecules are closely packed and parallel to one another.The average degree of polymerization of cotton is 9000-15000 which is so higher than the average crystallinity of the viscose rayon and wood pulp. Higher degree of polymerization and crystallinity are associated with higher fiber strengths.

Fiber Properties:

Cotton is the most used textile fiber in the world. All the properties of cotton have made it as a best textile fiber to use as many kinds of wear. Most folks prefer items made out of cotton than those that contain synthetic fibers. It feels comfortable when touches to the skin, has good absorbency, is machine washable, it holds the color well and prints well, and of course, it drapes well when worn. The bellow properties are available in the cotton.

Physical Properties:

Fiber Length: Length is most important property to any kind of fiber. Every fiber should be thousand times longer than its diameter. Cotton has an excellent length and breadth ratio such as 1000-15000. To be a fiber it should have a minimum length. Length of cotton fiber varies from .5 inch to 2.5 inches. Sea Island cotton has the maximum length and it is 2.0 inches to over.  

Fiber Strength: After having a minimum length of a fiber, it would contain sufficient strength or tenacity to spin into yarn. Cotton has a moderate strength like 3 to 5 gm/denier. Tensile strength of cotton depends on its moistening. When cotton fiber wets, its strength increases. Wet cotton is about 2 times stronger than dry cotton.

Fiber Fineness and Maturity: Micronaire measurements reflect fiber fineness and maturity. More the micronaire value, coarse the cotton will be. The range of cotton fiber fineness is between 3.5 to 6 micro gram per inch. On the other hand maturity is generally expressed as maturity ratio (wall area divided by perimeter squared).

Elasticity: Cotton has a very low elastic recovery property. Recovery from deformation of it from applying loads is so poor. Under some chemical treatment it can be increased but other problems may be arisen such as harsh feeling. At 2% extension of cotton has an elastic recovery of 74% and at 5% extension cotton has an elastic recovery of 45%.

Color: The color of cotton fibers is suffered by climatic conditions, effects regarding insects and pests in addition to the fungus, type of soil, storage and so on. There are several known categories of color: white, gray, spotted, tinged, and yellow stained. As the color of cotton deteriorates, the method capability on the materials reduces.

Moisture Regain: Cotton fiber has an excellent MR percentage in its constituents. It belongs to 7 to 10  percent MR. But the standard MR% of cotton fiber is 8.5

Abrasion Resistance: Abrasion resistance of cotton is moderately good.

Heat Resistance: The following property of cotton fiber is good or moderate.

Trash and Neps: A trash measurement describes how much non-lint materials in the fiber. The actual values associated with trash information ought to be in the range from 0 to 1. 6%. Trash content is highly correlated to leaf grade of the sample. A nep is usually a modest matted fiber knot typically attributable to processing. Neps can be scored by the AFIS nep tester and claimed for the final amount associated with neps for each 0. 5 grams on the fiber and average size in millimeters.

Chemical Properties of Cotton: Cotton swells in a high humidity environment, in water and in concentrated solutions of certain acids, salts and bases. The swelling effect is usually attributed to the sorption of highly hydrated ions.

Cotton is attacked by hot dilute or cold concentrated acid solutions. Acid hydrolysis of cellulose produces hydro-celluloses. Cold weak acids do not affect it. The fibers show excellent resistance to alkali. There are a few other solvents that will dissolve cotton completely. One of them is a copper complex of cupramonium hydroxide and cupriethylene diamine

Cotton is not affected by bleach and strong oxidizing bleaching agents covert it into oxi-cellulose.

Cotton degradation is usually attributed to oxidation, hydrolysis or both. Oxidation of cellulose can lead to two types of so-called oxy-cellulose, depending on the environment, in which the oxidation takes place.



End Uses of Cotton Fiber: The most prominent fiber in the world it is, so it has a wide range of uses from domestic purpose to wear. For flexibility, soft handle in addition to comfort and excellent moisture containing property it can be used for all types of wearing cloths.

It is used from swimwear, suits, jackets, skirts, pants, to home fashion. Includes curtains, draperies, comforters, towels, napkins and more.

It is also used in industry to make tire cord, bag, shoe, conveyor and different medical related textile materials such as bandage or medical thread.