Cotton classification

One method of classifying acid dyes is to divide them into groups according to their application behavior. The traditional wool/nylon/cotton classification is customarily employed by the Colour Index and is therefore used here, too. 

Cotton bale weights vary from about 375 to 515 lb (170 to 233 kg) depending on the country in which they are produced (see Table 1.1). A pound of cotton contains 100 million or more individual fibers and each individual fiber varies in properties along its length from one end to the other. Cotton classification is a practical, cost-efficient way of measuring the general quality and physical attributes of bales of cotton fiber that affect the quality of the finished product and manufacturing efficiency and allows a market value to be established for the cotton to facilitate utilization. 

The official cotton standards of the United States for the grade of Upland cotton are also called the universal standards. Leading cotton associations in major cotton-consuming countries meet periodically to establish a continuing consensus of cotton classification. International conferences are held every 3 years in the United States to consider revisions and to ensure accurate reproduction of the standards. By this method, the U.S. cotton classification system maintains sensitivity and responsiveness to cotton consumer needs. 

There is a worldwide movement toward the increased use of instrument measurements such as the HVI in characterizing cotton quality and in cotton classification. This is encouraged by international bodies such as the International Cotton Advisory Committee (ICAC) and the International Textile Manufacturers Federation (ITMF). 

Classification by usage or appHcation is the principal system adopted by the Colour Index (5). Because the most important textile fibers are cotton (qv) and polyester, the most important dye types are those used for dyeing these two fibers, including polyester—cotton blends (see Fibers, polyester). 

Native or processed cellulose (e.g., cotton, Avicel, filter paper) and its soluble derivatives (e.g., CMC, HEC3) are substrates most often used in the study of cellulases. The classification based on the use of these substrates (l,4-/ -D-glucan cellobiohydrolases (CBH), exo-cellulases, Avicelases and... 

Almost pure cellulose is found in pith, absorbent cotton in some filter papers. Pure cellulose is most readily obtd from cotton by treating it with dil alkalies acids and thoroughly washing, with water. Another source of cellulose is wood(mostly coniferous) which contains 50-60% cellulose and strawfmostly cereal) which contains 30-40%. A common classification of celluloses is based on their solubilities in aq alkalies If cellulose is treated with NaOH soln of ca 18% at 20°, it will swell and much of the material, which is of short chain length, will dissolve. The residue from this treatment is called alpha cellulose. 

This chapter is principally concerned with ligand systems which contain a carbon atom linked to two oxygen atoms. In the vast majority of the complexes to be considered the donor atom is the relatively small, less polarizable oxygen atom, i.e. hard under the Pearson classification. As a consequence these ligands are seldom found in conjunction with low oxidation state metals. Considerable advances have been made in this area in recent years. The most notable of these has been the work of Cotton, who has made extensive use of the ability of such ligands to bring metal... 

Coproporphyrin I synthesis, 816 Coronands classification, 919 metal ion complexes, 928,938 Corphins, 855 Coninoids, 983 Corrins, 871-888 demetallation, 882 deuteration, 879 electrophilic reactions, 879 metallation, 882 NMR, 878 nucleophilicity, 886 nucleophilic reactions, 879 oxidation, 879 oxidative lactamization, 880 oxidative lactonization, 880 photochemistry, 887 reactions, 879 at metal, 885 rearrangements, 879 redox chemistry, 888 spectra, 877 synthesis, 878 Corroles, 871-888 demetallation, 874 deuteration, 872 hydrogenation, 872 metallation, 874 reactions, 872 at metal, 875 redox chemistry, 876 synthesis, 871 Corticotropin zinc complexes medical use, 966 Cotton effect anils, 717... 

All of the top nine cotton pesticides in California are labeled by the U.S. Environmental Protection Agency as Category I or Category II materials, the most toxic classifications. 

Direct or substantive dyes are colored compounds that are mainly used to dye materials made from natural or regenerated cellulose (e.g., cotton, jute, viscose, or paper) without employing mordants as auxiliaries. The essential requirement for classification of a dye in this group is its substantivity, i.e., its absorption from an aqueous salt-containing solution onto cellulosic materials. Absorption onto cotton takes place in a neutral to soda alkaline medium, and onto paper in a weakly acid to neutral medium. 

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