Cotton Fiber Chemistry and Technology by Phillip J. Wakelyn, Alfred D. French

Table of Contents

Preface
This was published originally as a chapter in the Handbook of Fiber Chemistry, Third Edition. Because of particular interest in the new revised and expanded Cotton Fiber chapter, it is also now being published as a separate book. Why does this complex carbohydrate ‘‘cotton’’ get so much attention? Cotton’s many unique properties have made it useful as a textile fiber for over 5000 years. It is the most imporotant natural textile fiber used in spinning to produce apparel, home furnishings and industrial products—about 40% of all textile fiber consumed in the world. Annually, there is over 25 million metric tons of cotton produced in about 80 countries in the world and it is one of the lead crops to be genetically engineered.

Despite over 150 years of laboratory research on cotton and cellulose, there is much exciting new work to learn about. This book’s nationally and internationally recognized contributors have spent their careers gaining in-depth knowledge of cotton fiber chemistry and technology. This includes information on cotton’s origin, biosynthesis, production, structural properties/crystal structure of cellulose, morphology, chemical properties/reaction characteristics, degratation, purification, physical properties, classification and characterization (classing), and utilization which is discussed in this book. Some 650 references cited provide a more in-depth treatment of these subjects.

In particular, we acknowledge professor Menachem Lewin for his many important contributions to cotton chemistry and for inspiring this book. Without his strong support it would not exist. Glenn P. Johnson, ARS, SRRC, USDA was invaluable in converting and updating the previous chapter to this book. Fortunately, this book was mostly finished before hurricane Katrina devastated the city of New Orleans and the USDA Southern Regional Research Center where many of the contributors to this book worked.

In conclusion, we have striven to provide information about the chemistry and technology of cotton fiber.We hope this will assist readers in becoming more informed about the unusual carbohydrate called cotton and why it is such an important textile fiber.

General Description of Cotton
Cotton (Figure 1 .1) is the most important natural textile fiber , as well as cellulosic textile fiber, in the world , used to produce apparel , hom e furni shings, and indust rial prod ucts. Wo rldwide about 40% of the fiber co nsumed in 2004 was cotton [1]. (See also Table 9.1 W orld Pro duction of Textile Fibers on pa ge 130.) Cotton is grow n most ly for fiber but it is also a food cro p (cotton seed)— the major end uses for cottons eeds are vegetab le oil for hum an consumpt ion; whole seed, meal, an d hulls for animal feed; and linters for batting and che mical cellu lose.

Its or igin, de velopm ent, morpholog y, ch emistry , purif ication, an d utilizat ion have be en discus sed by many authors [2–12]. The chemistry , struc ture, an d reaction ch aracteris tics of cellu lose, the carboh ydrate polyme r that forms the fiber , are tho roughly treat ed in a num ber of excell ent works [8,9 ,12–19 ]. Thi s book is intende d to provide an ov erview of the current state of knowl edge of the cotton fiber . M uch of the informat ion report ed here is taken from the referen ces cited at the end of the book, which sho uld be consult ed for a more in-dept h treatment .

Cotton fibers are seed hairs from plan ts of the ord er Malval es, family Malvac eae, tri be Gossy pieae, and genu s Gossy pium [2–5,10,1 1]. Botan ically, there are four princip al domesticated specie s of c otton of co mmercial impor tance: hirs utum, b arbaden se, aboreum, and herbace um . Thi rty-thre e species are current ly recogni zed; howev er, all but these four are wild shrubs of no commer cial value. Eac h one of the co mmercial ly important specie s contai ns many diff erent varietie s developed through breeding program s to pr oduce co ttons with continua lly impr oving propert ies (e.g., fast er matur ing, increa sed yields, and improv ed insect and diseas e resistance ) and fiber s wi th great er length, strength, and unifor mity.

Gossypi um hirsutum , a tetraploi d, ha s been developed in the Unit ed State s from cotton nativ e to Mexico and Cent ral America an d includes all of the many commer cial varietie s of Ame rican Upland c otton. Upland cottons now provide over 90% of the current world pr oduction of raw co tton fiber . The lengt hs, or stapl e lengths, of the Upland cotton fiber vary from abou t 7 8 to 11 2 in. (22–36 mm) , and the micron aire value (an indica tor of fiber finene ss an d matur ity but not nec essarily a reliable measur e of either; see Chapter 8) ranges from 3.8 to 5.0. If grow n in the United State s, G. hirs utum lint fiber s are 26–30 mm (1 to 1–3 =16 in.) long [20]. Fiber from G. hirsutum is wid ely used in ap parel, home furni shings , an d indust rial products .

Gossypi um barbade nse , a tetraploi d, is of early South Ame rican origin and provides the longest staple lengt hs. The fiber is long and fine with a stapl e length usu ally great er than 13 8 in. (35 mm) and a micr onaire value of below 4.0. If grow n in the United State s., G. barbade nse lint fibers are usually 33–36 mm (1 5 6 to 1 1 2 in.) long [20]. Commonly known as extra-long-staple (ELS), it supplies about 8% of the current world production of cotton fiber. This group includes the commercial varieties of Egyptian, American–Egyptian, and Sea Island cottons. Egypt and Sudan are the primary producers of ELS cottons in the world today. Pima, which is also ELS cotton, is a complex cross of Egyptian and American Upland strains and is grown in the western United States (mainly California with some in Arizona, southwestern Texas, and New Mexico), as well as in South America. Pima has many of the characteristics of the better Egyptian cottons. This fiber from G. barbadense is used for the production of highquality apparel, luxury fabrics, specialty yarns for lace and knitted goods, and sewing thread.