Cotton 3n214f

The Chemistry Of The Cotton Fiber By Dr. BOWMAN. Every chemist knows that cotton is chiefly composed of cellulose, CHO, with some other substances in smaller quantities. This, although the usual opinion, is only true in a partial sense, as the author found on investigating samples of cotton from various sources. Thus, while mere cellulose contains carbon 44.44 per cent. and hydrogen 6.173, he found in Surat cotton 7.6 per cent. of hydrogen, in American cotton 6.3 per cent., and in Egyptian cotton 7.2 per cent. The fact is that along with cellulose in ordinary cotton there are a number of celluloid bodies derived from the inspissated juices of the cotton plant. In order to gain information on this subject, the author has grown cotton under glass, and analyzed it at various stages of its life history. In the early stage of unripeness he has found an astringent substance in the fiber. This substance disappears as the plant ripens, and seems to closely resemble some forms of tannin. Doubtless the presence of this body in cotton put upon the market in an unripe condition may for certain dark stains sometimes appearing in the finished calicoes. The tannin matter forms dark stains with any compound or salt of iron, and is a great bugbear to the manufacturer. Some years ago there was quite a panic because of the prevalence of these stains, and people in Yorkshire began to think the spinners were using some new or inferior kind of oil. Dr. Bowman made inquiries, and found that in Egypt during that year the season had been very foggy and unfavorable to the ripening of the cotton, and it seemed probable that these tannin-like matters were present in the fiber, and led to the disastrous results. Although the hydrogen and oxygen present in pure cellulose are in the same relative proportions as in water, they do not exist as water in the compound. There is, however, in cotton a certain amount of water present in a state of loose combination with the cellulose, and the celluloid bodies previously referred to appear to contain water similarly combined, but in greater proportion. Oxycellulose is another body present in the cotton fiber. It is a triple cellulose, in which four atoms of hydrogen are replaced by one atom of oxygen, and like cellulose forms nitro compounds analogous to nitro glycerine. It is probable that the presence of this oxycellulose has a marked influence upon the behavior of cotton, especially with dye matters. The earthy substances in cotton are also of importance. These are potassium carbonate, chloride, and sulphate, with similar sodium salts, and these vary in different samples of cotton, and possibly influence its properties to some extent. Then there are oily matters in the young fiber which, upon its ripening, become the waxy matter which Dr. Schunk has investigated. Resin also is present, and having a high melting point is not removed by the manipulative processes that cotton is subjected to. When this is in excessive amount, it comes to the surface of the goods after dyeing.

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Cotton Classroom 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. Works Cited Wakelyn, Phillip. CRC Press (2006) 15-18. 18 Sep 2008 . 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. Works Cited 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 Copyright © 2008 Department of Textile and Apparel Management University of Missouri 137 Stanley Hall, Columbia, MO 65211 Telephone: 573.882.7317 Fax: 573.882.3289

Chemical Structure of Cotton