Viscose rayon properties

Neste patented an industrial route to a cellulose carbamate pulp (90) which was stable enough to be shipped into rayon plants for dissolution as if it were xanthate. The carbamate solution could be spun into sulfuric acid or sodium carbonate solutions, to give fibers which when completely regenerated had similar properties to viscose rayon. When incompletely regenerated they were sufficientiy self-bonding for use in papermaking. The process was said to be cheaper than the viscose route and to have a lower environmental impact (91). It has not been commercialized, so no confirmation of its potential is yet available. 

Most of the above can be made into plastic films - primarily used for wrapping. Film properties vary widely from permeable for food to impermeable to preserve dryness. Paper, treated or untreated, has been used for many years as a covering film, but has low strength when wet and is difficult to make transparent. In the 1920s, the transparency of cellophane revolutionized wrap. It is regenerated cellulose, like viscose rayon, except it is extruded in sheet instead of fiber, unfortunately it is sensitive to water and humidity. 

P.B.15 1, like other types of Copper Phthalocyanine, find extensive use in the spin dyeing of polypropylene, polyester, polyamide, secondary acetate, viscose rayon, and spun rayon. In these, as in other media, P.B.15 1 is very lightfast, and its textile fastness properties are almost entirely if not entirely satisfactory. 

This is the first reported study of the spinning of mesomorphic cellulose solutions, but no fiber properties were given. Quenin et al. (14) used a d -jet, wet spinning system to spin cellulose/MMNO-H20 solutions. Fiber properties equiv dent to the best viscose rayon fiber were obtained. 

The cuprammonia process, the viscose process, and the acetate process have been employed for the production of rayon. Cuprammonia and viscose rayons have similar chemical and physical properties. Both are easily dyed and lose their strength when wet because of a disruption of hydrogen bonding this wet strength is improved through chemical treatment of the rayon fabrics. Acetate rayon is readily softened in the ironing process and loses its luster in boiling water. 

D-glucofuranose and l,4 3,6-dianhydro-a-D-glucopyranose. The purity and physical properties of cellulose appear to have a significant efiFect on the yield of levoglucosan. Madorsky and asso-ciates " have shown that viscose rayon is pyrolyzed faster than cotton, and provides a lower yield of tar and higher proportions of water, carbon monoxide, and carbon dioxide. 

Standard viscose and polynosic rayons are blended with cotton for improved physico-chemical properties of the blended fabric. The increase in tensile strength brought about by blending wool with viscose is well-known. Fabrics containing around 65% triacetate with viscose may be given durable pleats. Bulked or textured nylon is sometimes used with viscose rayon for fabrics. Table 4.17 shows... 

Because of consumer demand in the second half of this century for easy care textiles, interest in the reactivity of cellulose from the ever popular cotton and viscose rayon preceded interest in the other products. In fact, it is the alcohol functionality of cotton and viscose cellulose that is responsible for improvements in the aesthetic and functional properties of their fibers and fabrics. 

Harry, I.D., Saha, B., and Cumming, I.W., Surface properties of electrochemically oxidised viscose rayon based carbon fibres. Carbon, 45, 766, 2007. 

Artificial silk (viscose rayon) is spun from a viscous medium that is produced by reacting cellulose with carbon disulfide in alkali. The unusual success of this reaction prompted scientists to analyze similar reactions with starch, and indeed, starch viscose can be obtained.2134,2135 The properties of xanthates (32), mainly the degree of substitution, depend on such reaction conditions as the proportions and concentrations of reagents, and the duration and temperature of the process. Xanthation of starch using 2-3 moles of sodium hydroxide in 5-20% aqueous solutions per mole of starch and 20-25 mL of carbon disulfide per 10 g of starch is complete within 24 h of shaking at room temperature. Further studies suggested a 3-molar NaOH solution as the most suitable.2136 The temperature is a critical parameter and... 

The viscosity of the viscose, an important processing parameter, and the final rayon properties are dependent on the average chain length or DP of the cellulose. Control of this variable is achieved by aging the alkali cellulose crumb under conditions yielding the appropriate extent of depolymerization for the type of rayon produced. 

In 1897, Topham [117] first discovered that ripening is necessary in the preparation of a good spinning viscose and to obtain desired rayon properties. 

The classification of viscose rayon fibers into different types is done mostly on the basis of physical and chemical properties. Fibers produced by nonviscose processes are usually identified separately. It has already been described how the fiber can be produced to have almost any desired structure, and it is considered to be the most versatile of all human-made fibers. It is available in various cross-sectional shapes, from multilobed, serrated, and round to flat longitudinally, it may be straight or curled (crimped). It comes in fine deniers... 

The properties of cuprammonium rayon are sufficiently different from those of viscose rayon that today it is produced as a specialty fiber for several applications. Apart from its use as a substitute for silk in scarves, ties, fine dresses, and linings, the use of hollow cuprammonium fibers for hemodialysis in artificial kidneys has become important. 

The abrasion resistance of cellulose acetate is lower compared with that of other fibers. Abrasion resistance was measured by the wet-flex abrasion determined with the Stoll Abrasion Tester. Abrasion resistance of several fibers was rated in the following decreasing order nylon, polyester fiber, acrylic fiber, wool, cotton, viscose rayon, and acetate. It was suggested that the abrasion resistance of fabrics is related to the strength and the recovery properties of fibers. The fact that acetate is not a particularly strong fiber probably accounts in part for its inferior abrasion resistance. Heat-treated cellulose triacetate fabrics have both higher tensile strength and abrasion resistance than secondary acetate fabrics for the conditions of dry, wet, and hot wet (80°C) [53,63]. 

Shinohara and Tanzawa examined the effect of orientation on the dynamic properties of viscose rayon films and fibres. (Only an abstract of their studies appears to be available in English.) Making the assumption that the structure was polycrystalline they deduced a relation between extensional and shear moduli in terms of an orientation factor tan d for each modulus was found to be independent of orientation. 

Rubber from trees has been used in both solid and latex form, and also converted further into isomerized and chlorinated polymers of very different properties and uses. Wood from trees is used directly for plywood, composition board, and wood-flour reinforcement of phenolic resins. The cellulose from wood is purified and used for laminates and for regenerated cellulose products such as cellophane, viscose rayon, and vulcanized fibre. The lignin from wood has been explored for use in plastics, but never carried through to complete commercial success. 

This chapter deals merely with exposure to common organic solvents which are used in large quantities to dissolve fats, resins, and other materials. Very dangerous chemicals, such as benzene, which are no more used as solvents due to their toxic properties, will not be discussed even though they may have had even extensive uses as solvents earlier and even though those may be still important chemicals as petroleum components or as intermediates for other chemicals. Also, solvents with very specialized uses, such as carbon disulfide the use of which is practically limited to viscose rayon industry and laboratories, are only... 

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