Cotton :
The word cotton is derived from the Arabic. Cotton fiber is classified as a natural vegetable seed staple fiber. It grows on a plant of a botanical name Gossypium. Cotton is a member of the mallow family. Each fiber is a single plant cell in the outer layer of the cotton seed. These seed hairs are called lint. Fibers which are too short to be spun into yarn are called linters.
Early History :
Cotton fabrics were made by the ancient Egyptian and by the earliest of Chinese civilization. Samples of cotton material have been found in Indian tombs dating back to the year 3000 B.C. There is some evidence that cotton may have been in use in Egypt in 12000 B.C. Specimens of woven cotton fabric have been found in desert tombs discovered in peruse. At the time of roman empire cotton growing and manufacture become established around the shore of the Mediterranean . Cotton was being grown on the Greek mainland from the 8th century A.D. During the 12th and 13th century Europe become the important cotton manufacturer. By the end of the 17th century Britain had become an exporter of cotton fabrics.
Cotton fabrics were made by the ancient Egyptian and by the earliest of Chinese civilization. Samples of cotton material have been found in Indian tombs dating back to the year 3000 B.C. There is some evidence that cotton may have been in use in Egypt in 12000 B.C. Specimens of woven cotton fabric have been found in desert tombs discovered in peruse. At the time of roman empire cotton growing and manufacture become established around the shore of the Mediterranean . Cotton was being grown on the Greek mainland from the 8th century A.D. During the 12th and 13th century Europe become the important cotton manufacturer. By the end of the 17th century Britain had become an exporter of cotton fabrics.
Structure of Cotton fiber :
Each hair consists of a single elongated cell, the upper end of which tapers to a point , while the lover end is open where it has been removed form the seed by gin. Fibers contain many convolutions throughout its length.
In cotton fiber the outer most layer is known as cuticle and is a thin film of fats pectin’s and waxes. Beneath this is a primary wall is arranged in a crisscross pattern. Further toward the center is
secondary wall composed of cellulose. It is further subcategorized in 3 zones. The outermost S1 of secondary wall is comparatively thin layer of fibrils with an angle of 20o to 35o . The S2 zone which is situated inside S1 also composed of cellulose with a some what angle of 20o to 30o ,like those in S1 are organized so that there are periodical reversal in the direction of the spiral. In very mature cotton the S3 layer can be detected adjacent to the lining of the lumen and it consists of the mineral salts and the proteins derived from the drying up of the cell sap. Next to the secondary wall there is a hollow central core known as the Lumen.
In a young and growing cell the whole of the space is filled with cell sap. When the cell becomes mature the sap disappears leaving an almost empty structure. As the sap evaporated then protein and salts dried and deposit on the S3 layer of secondary wall, leaving the lumen as hollow core.
Each hair consists of a single elongated cell, the upper end of which tapers to a point , while the lover end is open where it has been removed form the seed by gin. Fibers contain many convolutions throughout its length.
In cotton fiber the outer most layer is known as cuticle and is a thin film of fats pectin’s and waxes. Beneath this is a primary wall is arranged in a crisscross pattern. Further toward the center is
secondary wall composed of cellulose. It is further subcategorized in 3 zones. The outermost S1 of secondary wall is comparatively thin layer of fibrils with an angle of 20o to 35o . The S2 zone which is situated inside S1 also composed of cellulose with a some what angle of 20o to 30o ,like those in S1 are organized so that there are periodical reversal in the direction of the spiral. In very mature cotton the S3 layer can be detected adjacent to the lining of the lumen and it consists of the mineral salts and the proteins derived from the drying up of the cell sap. Next to the secondary wall there is a hollow central core known as the Lumen.
In a young and growing cell the whole of the space is filled with cell sap. When the cell becomes mature the sap disappears leaving an almost empty structure. As the sap evaporated then protein and salts dried and deposit on the S3 layer of secondary wall, leaving the lumen as hollow core.
Constituents Of Raw Cotton :
The approximate composition of raw cotton is as follows.
Cellulose 85.5%
Oil & Waxes 0.5%
Proteins, Pectose and coloring matter 5.0%
Mineral Matter 1.0%
Moisture 8.0%
Cotton Wax :
Cotton wax on hydrolysis was said to yield the following alcohol, Gossipyl alcohol C30H61OH, Montanyl alcohol C28H57OH and ceryl alcohol C26H53OH. Later investigation prove that gossipyl and montanyl alcohol are not in pure state but they are in fats mixture. These alcohol combine with fatty acids to form waxes. Fasts are esters of fatty acid with glycerol and are hydrolyzed into soap and glycerol quite easily by boiling in an aqueous solution of sodium hydroxide.
Nitrogen Constituents of raw Cotton :
These are derived from cell sap. They consist of protein and the degradation product of protein such as polypeptides and amino acids. It is believed that nitrogen containing compounds may b associated with the natural coloring matter.
Pectates OR Pectose :
Natural cotton contains derivatives of pectic acid. They appear to exist as calcium and magnesium pectates. Pectic acid is polymer consisting of galacturonic acid unit
Cotton wax on hydrolysis was said to yield the following alcohol, Gossipyl alcohol C30H61OH, Montanyl alcohol C28H57OH and ceryl alcohol C26H53OH. Later investigation prove that gossipyl and montanyl alcohol are not in pure state but they are in fats mixture. These alcohol combine with fatty acids to form waxes. Fasts are esters of fatty acid with glycerol and are hydrolyzed into soap and glycerol quite easily by boiling in an aqueous solution of sodium hydroxide.
Nitrogen Constituents of raw Cotton :
These are derived from cell sap. They consist of protein and the degradation product of protein such as polypeptides and amino acids. It is believed that nitrogen containing compounds may b associated with the natural coloring matter.
Pectates OR Pectose :
Natural cotton contains derivatives of pectic acid. They appear to exist as calcium and magnesium pectates. Pectic acid is polymer consisting of galacturonic acid unit
Mineral Matters :
The nature and amount of mineral matter found in cotton depends to some extent on the composition of the soil on which it is grown. It is the residue of the salts contained on the sap when the cell is still living. The exact nature and proportions of the salts can vary significantly.
Cellulose : (Chemical Structure of Cellulose)
When all the impurities have been removed the main constituent of the fiber cellulose remains. Cellulose has an empirical formula C6H1OO5. Pure cellulose is a white substance with a specific gravity of 1.5. It has been known for a long time that one of the products of the hydrolysis of cellulose is glucose. This means that cellulose consists of nothing but glucose molecules link together. Starch and glycogen also gives theoretical yields of glucose on hydrolysis but no man has ever succeeded in making a fibrous substance out of them. So there must be some unique structural arrangement of the glucose units within the cellulose. There are two forms of dextrorotary glucose known as the alpha and beta glucose. The difference between them lies in the distribution of the hydroxyl groups above and below the pyrnose ring.
When all the impurities have been removed the main constituent of the fiber cellulose remains. Cellulose has an empirical formula C6H1OO5. Pure cellulose is a white substance with a specific gravity of 1.5. It has been known for a long time that one of the products of the hydrolysis of cellulose is glucose. This means that cellulose consists of nothing but glucose molecules link together. Starch and glycogen also gives theoretical yields of glucose on hydrolysis but no man has ever succeeded in making a fibrous substance out of them. So there must be some unique structural arrangement of the glucose units within the cellulose. There are two forms of dextrorotary glucose known as the alpha and beta glucose. The difference between them lies in the distribution of the hydroxyl groups above and below the pyrnose ring.
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