Cuprammonium method

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. 

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... 

Laser-based refractive index detector, Cuprammonium reagent,4-Aminobenzoic acid reagent, Indirect detection methods for cyclodex-trins, and sugar phosphates Reversible derivatization using 2-amino-pyridine ... 

The TAPPI64 methods are satisfactory for analysis of cuprammonium alternatively, electrolytic depositions methods may be employed for the copper66 and Kjeldahl techniques for the ammonia. 

The methyl ester of oxycellulose, produced by alkaline permanganate oxidation of cuprammonium cellulose followed by treatment with diazomethane, has been reacted with protein by the azide method [34]. Acidic oxyce]]uloses are aiso able to react with alcohols and amines, including proteins, to form esters or amide derivatives. 

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. "... 

Fluidity results determined in Cuxam and Cuen for chemically damaged cotton are correlated with viscosity values obtained in Cadoxen and FeTNa solvents [16]. The comparison and conversion of the viscosity values to apparent cuprammonium fluidity is a quick method of determining degradation of cotton occured in pretreatment processes [16]. 

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. 

The complexings of D-glucose, D-fructose, and maltose with borate anions have been studied by polarimetric, conductivity, and pH measurements, and circular dichroism methods have been used to investigate the complexing of cuprammonium ions with carbohydrate diols and amino-alcohols. An examination of the c.d. spectra of fifteen methyl 3-acetamido-3,6-dideoxyhexopyranoside derivatives measured in methanol, 2,2,2-trifluoroethanol, and acetonitrile su ests that the amide group is not completely planar and may show chirality. The n it transition of the carboxylic acid carbonyl groups at... 

The rate of breakage of cellulose bonds in cotton is readily found from the changes in the degree of polymerization (DP) as exposure continues, using the cuprammonium fluidity as a measure of the DP. In jute, however, this method is not always satisfactory because it is difficult to achieve a complete dissolution of the cellulose component in cuprammonium hydroxide because of interference from the lignin in the fiber. Moreover, preliminary removal of lignin is not advisable, as whatever the process used, it is always liable to cause some degradation of the cellulose. 

Several known systems dissolve cellulose (126-129). These systems range from solutions in protonic acids (e.g., 78% phosphoric acid) to metallic complexes (e.g., cuprammonium). All known methods for dissolving cellulose can be fit into four main categories (128) cellulose acting as abase, cellulose acting as an acid, cellulose complexes, and cellulose derivatives. The cellulose derivatives are distinguished from those discussed previously in that dissolution occurs simultaneously with derivative formation and the derivative produced can easily be regenerated (129). 

Cuprammonium Process. In the cuprammonium (cuoxam) process, linters or high-quality wood pulp is dissolved in [Cu(NH3)4] [OH] " (cuoxam). The method varies slightly according to whether copper silk (Bemberg silk) or cell glass (Cellophane ) is required. 

Regenerated cellulose films and hollow fibres used in haemodialysers have been prepared by a method known as the cuprammonium process. Cellulose is dissolved in a solution of ammonia and cupric oxide. The complex cupric salts are water-soluble and cellulose is regenerated by treatment with acid. Cuprophan is prepared by this process. 

Various methods are used to improve the membrane properties. One major factor is the relationship between membrane thickness and permeation properties. Figure 4 shows the relationship for cuprammonium rayon hollow fiber which has been subjected to various post-spinning treatments. Cuprammonium rayon hollow fibers can now be produced to meet a broad range of property requirements, by modification of the hollow fiber dimensions and post-spinning treatment. Figure 5 shows that the ultrafiltration ratio and the mass transfer coefficient are virtually independent. 

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