Cellulose cuprammonium rayon

Schweizer s reagent The dark blue solution obtained by dissolving Cu(OH)2 in concentrated ammonia solution. Used as a solvent for cellulose, the cellulose is precipitated on acidification. Used in the cuprammonium process for the manufacture of rayon. 

Dissolution of the cellulose in cuprammonium solution followed by acid coagulation of extruded fibre ( cuprammonium rayon —no longer of commercial importance). In this case the acid converts the cuprammonium complex back into cellulose. 

The presence of free sulphuric acid in rayon-spinning baths limits application of the austenitic steels, but they are used for acetylation of cellulose in the acetate process. They are also used for dissolving and spinning solutions in the cuprammonium processes. 

This term was originally intended to denote all kinds of man-made textile fibres, but is now applied only to cellulose types. Viscose rayon (regenerated from a solution of cellulose xanthate in sodium hydroxide) accounts for the greater part of world rayon production. Acetate rayon and cuprammonium rayon are relatively unimportant. 

Amorphous Cellulose in Cotton and Cuprammonium Rayon by Periodate Oxidation"... 

Goldfinger and coworkers obtained the data shown in Table IX by this method. The difference in amorphous cellulose between linters and cotton is appreciable but attention is directed particularly to the behavior of cuprammonium rayon after being dried from water and after being... 

Today rayon is made by either the viscose or the cuprammonium process. The latter process is based on Schweitzer s discovery in 1857 that it is possible to dissolve cellulose in cuprammonium hydroxide, the soln being due to the formation of a Cu cellulose complex. The mfg procedure involves processing the cuprammonium soln by filtration and deaeration prior to pumping it thru holes in a spinneret into si alkaline w which coagulates the Cu-cellulose soln into rayon filaments. The filaments are then stretched to the desired fineness (Ref 11). The viscose process is the most widely used because of its great versatility and low cost operation. 

Viscose rayon is but one variety of rayon, a more general term for derivatized or reconstituted cellulose. Other rayons include fiber prepared from collodion, cellulose acetate, and cellulose fiber regenerated from a cellulose-copper ammonium solution cuprammonium rayon) (Kauffman 1993). 

Cuprammonium, Nitrocellulose, and Cellulose Acetate Processes for Rayon... 

The transformation of the sol into rayon came about through the reaction between the sol and the sulfuric acid. The method you used to make rayon in this experiment is the cuprammonium method. Chopped-up wood is the source of cellulose in the commercial application of this method. 

In the original process, the cellulose nitrate itself was used as the fiber (hence its satirical description as mother-in-law silk ). The regenerating agent is ammonium hydrosulfide. The basic process was first demonstrated by J.W. Swan in London in 1885 but commercialized by Count L.M.H.B. de Chardonnet ( Father of the rayon industry ) in France in 1891 and operated there until 1934. The last working factory, in Brazil, burned down in 1949. The other processes for making rayon fibers by regenerating cellulose ( viscose, cuprammonium) gave superior products. See also Rayon. 

Accessibility. The extent of etherification is often determined by the accessibility of a substrate under a given environment. As Segal discussed [8], the extent of methylation with ethereal diazomethane (indicated by methoxyl contents) increased in the order hydrocellulose (5.9%) < cotton (7%) < mercerized cotton (14.9%) < cuprammonium rayon (18.6%) < ball mill-ground cotton (20.6%). Crystallinity of the cellulose was considered to be a significant factor. 

Highly degraded cellulosic materials, such as viscose rayon, D.P. 250 to 350, may be dispersed in 8-12 % caustic at low temperatures. Upon increasing the temperature in a stepwise manner, the dispersed material may be fractionally precipitated. " This method of fractionation is of particular interest since viscosity data indicate that the state of dispersion of degraded cellulosic materials in caustic solution and in cuprammonium solution is similar. "... 

The fractionation of cellulosic materials dispersed in cuprammonium solution has usually been accompanied by an amount of degradation sufficient to render the results questionable. However, Battista and Sisson, " using acetone and n-propyl alcohol as precipitants, were able to resolve viscose rayon yam (D.P. 490) dispersed in cuprammonium solution into fractions varying in average degree of polymerization from 535 to 142, and from 615 to 132, respectively. 

A 0-5 per cent solution of a regenerated cellulose has a fluidity of about 40, which is approaching the limit of accuracy of measurement. It is therefore usual to work with a 2 per cent solution which brings fluidities into the range of 7-5 to 35,- and normally well-bleached regenerated cellulose rayon should have a fluidity of 11 to 12. For mixtures of cotton and viscose or other chemically similar rayons, the weights of fibre required per 100 ml of cuprammonium solution are given in Table 3.2. 

The manufacture of cuprammonium rayon is based upon Schweitzer s discovery that cellulose is dissolved by a solution of copper hydroxide in ammonia. Attempts to utilize this discovery for the preparation of fibres were made by Depaissis, but Pauly, in 1897, was the first to work the process on a commercial scale. His venture did not survive and it was left in abeyance until Bemberg took it up again in 1919 and succeeded because he introduced the method of stretch spinning, based on earlier work by Thiele. 

Cuprammonium rayon is made from scoured and bleached cotton linters or purified wood pulp with a high a cellulose content. The cellulose is washed and then pressed until it contains about 50 per cent of water. In this state, it is placed in a mechanical mixer together with cuprammonium solution and agitated until completely dissolved, whilst the temperature is maintained at 5° C (41 °F). The solution is then diluted to about 10 per cent concentration. After filtration and exposure to vacuum to remove air bubbles and dissolved gases, the solution is allowed to ripen in enclosed vessels until it is the desired viscosity. In modem practice copper carbonate is mixed intimately with the cellulose in a shredding machine and the resultant mass is then broken up and stirred for some hours with aqueous ammonia and caustic soda, when it passes into solution. 

Establishments primarily engaged in manufacturing cellulosic fibers (including cellulose acetate and regenerated cellulose such as rayon by the viscose or cuprammonium process) in the form of monofilament, yarn, staple, or tow suitable for further manufacturing on spindles, looms, knitting machines, or other textile processing equipment. 

Cellulose acetate monofilament, yarn, staple, or tow Cellulose fibers, manmade Cigarette tow, cellulosic fiber Cuprammonium fibers Fibers, rayon Horeshair, artificial rayon Nitrocellulose fibers Rayon primary products fibers, straw, strips, and yarn... 

The complete solubility of cellulose in cuprammonium solutions, discovered in 1857 by Schweizer, led to the development of the rayon industry, but, as in the case of alkali cellulose, the regenerated polymer is chemically the same as the precursor. Regeneration via cellulose xanthate solutions, invented by Cross... 

In 1937, Schweizer [91] discovered that cellulosic fibers such as cotton and hemp readily dissolve in copper hydroxide and ammonium hydroxide solutions. His system is recognized as the Schweizer reagent. The Bemberg Rayon Industry later utilized this solvent for the industrial production of cuprammonium fibers (or cuprammonium rayon) and developed the Bemberg process or cuprammonium process [92]. Kamide and Nishiyama [93] have recently published an excellent review on the history and science of cuprammonium technology. 

In 1920, the Tubize Company built a plant to produce the yarn in the United States. By 1934, however, other types of superior rayon had been developed, so the nitrocellulose plant was sold to a company in Brazil. Several incidents of explosions and fires caused by the incompletely denitrated cellulose resulted in setbacks to the Chardonnet silk process, but, fortunately, the simultaneous development of cuprammonium and viscose solutions for spinning rayon rapidly replaced the more dangerous nitrocellulose fibers. 

The name rayon was officially adopted in 1924 by the National Retail Dry Goods Association. Prior to this, the fiber was called artificial silk, wood-silk, or viscose silk. On October 26, 1937, the Federal Trade Commission (FTC) officially defined rayon as a textile fiber or yarn produced chemically from cellulose or with a cellulose base. This definition covered cuprammonium and viscose rayon as well as acetate fiber. To avoid confusion in the trade, FTC rules were adopted on December 11, 1951, which defined rayon as man-made textile fibers and filaments composed of regenerated cellulose. A separate definition was adopted for acetate, man-made textile fibers and filaments composed of cellulose acetate. ... 

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