Cotton steeping

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... 

How -elimination reactions and subsequent processes under alkaline conditions affect the carbonyl groups and the Mw of an oxidized cotton linters is shown in Fig. 2. The initial concentration of carbonyls is 30 pmol/g, introduced by hypochlorite treatment at pH 7. The sample was treated with a buffer solution of pH 11 at 40 °C. The Mw suffers a steep decrease within the first 5 hours, the drop in carbonyls proceeds at a significantly lower rate. While the changes in Mw level off after approx. 20 hours of treatment, the carbonyl groups are slightly decreasing further (unpublished results). 

Gun-Cotton. Cocton-wool is immersed in a boilina dilute solution of potassium carbonate, then washed with water and well dried. It is now steeped for a few minutes in a cold mixture of 1 part of concentrated nitric acid and 3 of oil of vitriol, then squeezed, and again placed in a fresh acid mixture and leu there for 48 hours. It is then again well squeezed and washed for a long time with running water, and finally steeped in a solution of potassium carbonate. 

Lactones in acid-washed samples of modified cotton are not hydrolyzed in methylene blue solution. They may, however, be determined along with free carboxyl groups by steeping the material in a solution containing potassium iodide and iodate, sodium chloride, and an excess of sodium thiosulfate [427,428]. Hydrogen ions from the material liberate iodine according to the reaction... 

The activation treatment involves steeping cellulose (cotton or pulp fibers in sheet form) with cold 15 to 20% aqueous alkali for several hours. This alkali cellulose is subsequently reacted with reagents that consume alkali (Williamson synthesis) or alternatively in reactions in which alkali serves as catalyst (alkoxylation). Reactions are carried out between room temperature and 110 °C. Following reaction, cellulose ethers in solid fiber form (by virtue of being suspended in a small polar solvent such as isopropanol) are washed with aqueous alcohol, dried, and powdered by granulation (O Fig. 23). 

Alkali cellulose is prepared by steeping cellulose obtained from wood pulp or cotton fibers in sodium hydroxide solution. The alkaline cellulose is then reacted with sodium monochloro-acetate to produce carboxymethylcellulose sodium. Sodium chloride and sodium glycolate are obtained as by-products of this etherification. 

The simplest way of dyeing a fiber is by a direct dye. The dye is dissolved in water so that its concentration is about 0.02 to 0.1 per cent. The amount of dye depends on the weight of the cloth. For light shades the amount of dye is 0.05-0.3 per cent, and for deep shades 4-10 per cent, of the weight of the cloth. A small amount of sulfated alcohol soap is added to reduce the surface tension of the solution and thereby aid in the penetration of the dye. Inorganic salts are added to the dye bath, such as sodium chloride for cotton dyes and sodium sulfate for wool dyes, in amounts varying from 5 to 10 per cent. The fiber is steeped in the dye bath and heated at 80-100° until the proper shade has been... 

Desizing of cotton fabric can be accomplished by physical, chemical or combination of physical and chemical mechanism, namely rot steeping, acid steeping, treatment with enzyme and oxidising agents. In desizing, the starches and polymers that are applied which are insoluble, are converted into water soluble com-... 

After preliminary steeping the goods are rinsed. It is very important in cotton processing that the soluble products formed at one stage should be completely removed before subjecting the goods to the next. If they are not removed they may be reprecipitated in the next process or inhibit the action of the chemicals which are used. 

The nitrogen sources may be ammonium salts such as citrate, tartrate, malate, succinate, oxalate, acetate and the like amino acids and their mixtures, peptides or proteins, their hydrolysates, meat extracts, hydrosoluble fractions of cereal-like com or wheat corn malt extract, corn steep liquor, soya-bean meal, peanut meal, chick-pea meal, cotton bean meal. 

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