Cotton alkalis

The NH2 groups can be diazotized and reduced in the presence of thiosulphates and different metal ions. The effect of some metal ions, namely Fe ", Sn, Cu +, and Co on the graft yield of cotton modified with aryl diazonium groups via its reaction with 2,4-dichloro-6-(p-nitroaniline)-5-triazine in the presence of alkali and followed by reduction of nitro group was studied [4]. 

An older method of cellulose fiber modification is mercerization [22,33-36], which has been widely used on cotton textiles. Mercerization is an alkali treatment of cellulose fibers. It depends on the type and concentration of the alkalic solution, its temperature, time of treatment, tension of the material, and the additives used [33,36]. At present there is a tendency to use mercerization for natural fibers as well. Optimal conditions of mercerization ensure the improvement of the tensile properties [33-35,37] and absorption characteristics [33-35], which are important in the composing process. 

Cotton washing Nonionics, anionics (alkanesulfonates), alkali... 

Octamethyl pyrophosphoramide is a colorless oil, completely soluble in water, benzene, acetone, and many other common organic solvents except the paraffinic hydrocarbons. Its hydrolysis rate has not been measured, but it appears stable in the absence of alkali. In England, this systemic insecticide has been used to control aphids on hops. There it has been calculated that only a negligible quantity of the poison ultimately may find its way into the beer made from the hops. Despite calculations of this sort, the use of octamethyl pyrophosphoramide on food or fodder crops in this country is definitely not to be recommended. However, it may prove useful if properly applied to control certain insects, especially those attacking ornamental plants, such as rosebushes, and possibly on the cotton aphid and grape phylloxera. The compound has only recently been made available experimentally. 

But not all the potash, kelp, and barilla in Europe and North America could keep up with the cotton textile factories of Britain and France. France was in a particularly dire situation. Even under normal conditions, her natural sources of alkali were insufficient. Then France supported the American War of Independence, and British ships cut off the French supply of American potash. With gunpowder and textile industries dependent on potash, France had to find a way to make artificial alkali. 

Table 10.25 Effect of alkali used with peracetic acid at various pH values on the degree of polymerisation of cotton cellulose [256]...

Brighteners are applied to cotton by methods similar to direct dyes. By far the most common are triazinyl derivatives of diaminostilbenedisulphonic acid (DAS) of general formula 11.5, where M is an alkali metal, ammonium or alkylammonium cation. Examples of groups Ilj and R2 are shown in Table 11.1. Most suppliers of FBAs market such compounds, often called DAST brighteners. Products in this class have sometimes been marketed because the supplier needed to offer something different for commercial reasons, or to avoid infringing a competitor s patent, rather than for any real technological necessity. 

Cotton linters or wood pulp, usually in the form of sheets, is steeped in strong alkali (18-50%). The swollen sheets are then pressed to force out most of the excess alkali solution. This alkali cellulose is then shredded, and aged if low viscosity is desired. The aging process is the one followed in the viscose industry and is fully explained in any discussion of that process. More alkali may be introduced during the shredding, either as a concentrated solution or as solid alkali.18 The alkali... 

Ethylcellulose is made commercially by the action of ethyl chloride on an alkali cellulose prepared by steeping cotton linters or wood pulp... 

Solubilized vat Cotton, wool, cellulose, and protein fibers silk Impregnated fiber when treated with an oxidized agent usually sulfuric acid and sodium nitrite for cotton dichromate wool and silk therefore, no alkali is involved. This class is applicable to cellulose and protein fibers Dyeing, printing and wool in fast shades... 

Mercerization A process for modifying cotton textiles by treatment with alkali. The alkali is cold, conentrated aqueous sodium hydroxide it is subsequently removed by washing with acetic acid. The process is generally conducted while the textile is held under tension. The product has improved lustre and is easier to dye. Invented by J. Mercer in 1844. 

Viscose Also known as the Cross-Bevan-Beadle process. A process for making regenerated cellulose fibers. The product has been known by the generic name rayon since 1924. Cellulose, from cotton or wood, is first reacted with sodium hydroxide ( mercerization), yielding alkali cellulose. This is dissolved in carbon disulfide, yielding cellulose xanthate, which is dissolved in sodium hydroxide solution. Injection of this solution (known as viscose... 

Cotton linters (DP ca. 1000) Cotton linters alkali cellulose after shred- 98.5 5.3... 

The members of this class dye wool and silk directly, but cotton only when the latter is mordanted by tannin. They are fast neither to acids nor to alkalis for reasons which depend on important alterations in the compounds. If a little dilute hydrochloric acid is added to an aqueous solution of crystal violet the colour changes to green. One N(CH3)2-group takes part in the change and there is formed the salt with two equivalents of acid ... 

J. Koh, Alkali hydrolysis kinetics of alkali-clearable azo disperse dyes containing a fluorosulpho-nyl group and their fastness properties on PET/cotton blends. Dyes Pigm., 64 (2005) 17-23. 

---