Chemical Composition of Cotton Fiber
The chemical composition of cotton fiber consists of ninety-five percent cellulose, one point three percent protein, one point two percent ash, point six percent wax, point three percent sugar, and .8 percent organic acids, and other chemical compounds that make up three point one percent (Wakelyn pg. 15). The non-cellulose chemicals of cotton are usually located in the cuticle of the fiber.
The non-cellulose chemicals of cotton consist of protein, ash, wax, sugar and organic acids. Cotton wax is found on the outer surface of the fiber. The more wax found on cotton the greater the surface area of cotton there is; finer cotton generally has more cotton wax (Wakelyn pg. 16). Cotton wax is primarily long chains of fatty acids and alcohols. The cotton wax serves as a protective barrier for the cotton fiber. Sugar makes up point three percent of the cotton fiber, the sugar comes from two sources plant sugar and sugar from insects. The plant sugars occur from the growth process of the cotton plant (Wakelyn pg. 17). The plant sugars consist of monosaccharide, glucose and fructose. The insect sugars are mainly for whiteflies, the insect sugars can cause stickiness, which can lead to problems in the textile mills. Organic acids are found in the cotton fiber as metabolic residues. They are made up of malic acid and citric acid.
The non-cellulose chemicals of cotton are removed by using selective solvents. Some of these solvents include: hexane, chloroform, sodium hydroxide solutions, non-polar solvents, hot ethanol, and plain water (Wakelyn pg. 15). After removing all the non cellulose chemicals, the cotton fiber is approximately ninety-nine percent cellulose.
Wakelyn, Phillip. CRC Press (2006) 15-18. 18 Sep 2008 <http://books.google.com/books?id=3FUVqE3zczwC&pg=PP8&dq=cotton+fiber+information&sig=
By Chelsey Collop
Cotton Fiber and its Chemical Structure
The chemical composition of cotton, when picked, is about 94 percent cellulose; in finished fabrics is it 99 percent cellulose. Cotton contains carbon, hydrogen, and oxygen with reactive hydroxyl groups. Glucose is the basic unit of the cellulose molecule. Cotton may have as many as 10,000 glucose monomers per molecule. The molecular chains are arranged in long spiral linear chains within the fiber. The strength of a fiber is directly related to chain length.
Hydrogen bonding occurs between cellulose chains in a cotton fiber. There are three hydroxyl groups that protrude from the ring formed by one oxygen and five carbon atoms. These groups are polar meaning the electrons surrounding the atoms are not evenly distributed. The hydrogen atoms of the hydroxyl group are attracted to many of the oxygen atoms of the cellulose. This attraction is called hydrogen bonding. The bonding of hydrogen's within the ordered regions of the fibrils causes the molecules to draw closer to each other which increases the strength of the fiber. Hydrogen bonding also aids in moisture absorption. Cotton ranks among the most absorbent fibers because of Hydrogen bonding which contributes to cotton's comfort.
The chemical reactivity of cellulose is related to the hydroxyl groups of the glucose unit. Moisture, dyes, and many finishes cause these groups to readily react. Chemicals like chlorine bleaches attack the oxygen atom between or within the two ring units breaking the molecular chain of the cellulose.
Kadolph, Sara J., and Anna L. Langford. Textiles. 8th ed. Upper Saddle River, N.J.: Prentice-Hall, Inc., 1998.
Smith, Betty F., and Ira Block. Textiles in Perspective. Englewood Cliffs N.J.: Prentice-Hall, Inc., 1982.
By Melissa Deffenbaugh
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