Viscose rayon hydrolysis

A horizontal spinning machine, as is used in viscose rayon production, was first adopted. However, there is an essential difference in the coagulation mechanism of PVA and viscose solutions. In the case of viscose rayon, hydrolysis of cellulose-xanthogenate to regenerated... 

Viscose rayon is inherently a weak fibre, particularly when wet, therefore it is highly susceptible to damage if enzymatic hydrolysis is not controlled. The enzymatic hydrolysis of viscose fibres causes a decrease of the intrinsic viscosity from 250 to 140 ml/g and an increase in crystallinity from 29 to 39% after 44 h [34]. Strong changes of the structure, however, are not typical for the enzymatic hydrolysis of cellulosic materials. Neither cotton nor wood pulp show an essential decrease of the DP during enzymatic hydrolysis [35-37]. The kinetics of the enzymatic hydrolysis of regenerated cellulose fibres before and after acid prehydrolysis changes the kinetics from a monophasic to a biphasic first order reaction [38]. 

Buschle-Diller, G., Zeronian, S.H., Pan, N., Yoon, M.Y., 1994. Enzymatic hydrolysis of cotton, linen, ramie, and viscose rayon fabrics. Text. Res. J. 64, 270-279. 

The rednction-adsorption capacity for Pt (IV) on activated carbon fibers obtained from viscose rayon, sisal, and pitch was stndied by Fu et al. by chemical analysis of the reaction solutions and XPS studies of the deposited platinum. The reduction-adsorption capacity increased with the time of activation of the carbon fiber and was the highest in the case of viscose-based carbon fibers. Viscose-based carbon fibers were capable of reducing appreciable amonnts of Pt (IV), even withont activation. The state of the platinum product depended on the reaction conditions. Under acidic reaction conditions, the deposited platinnm was mainly in the elemental state. However, under the alkaline conditions, the liquid-phase hydrolysis of Pt (IV) becomes significant, and most of the platinum deposited on the activated carbon fiber surface was present as PtO, which was not further reduced to the metallic... 

Despite the anhydride stmcture, it is remarkably stable, surviving addition to the highly alkaline viscose, the acidic coagulating bath, and also resisting multiple laundering of the rayon fabric. The unusual stability may be attributed to the sulfur atoms, which enhance hydrophobicity, and to the stericaHy hindering neopentyl groups that retard hydrolysis. 

The first synthetic fiber for tires was rayon. Cellulose is initially treated with sodium hydroxide to form an alkali cellulose. It is then shredded and allowed to age in air, where it is oxidized and undergoes molecular weight reduction to enable subsequent spinning operations. Treatment with carbon disulfide produces cellulose xanthate, which is then dissolved in sodium hydroxide to form viscose. The material undergoes further hydrolysis and is then fed into spinnerets to produce the fiber. This fiber is passed through a bath of sulfuric acid and sodium sulfate, where the viscose fibers are further coagulated. 

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