Viscose fiber

Pulp mills. These separate the fibers of wood or other materials, such as rags, Enters, waste-paper, and straw, in order to create pulp. Mills may use chemical, semichemical, or mechanical processes, and may create coproducts such as turpentine and tall oil. Most pulp mills bleach the pulp they produce, and, when wastepaper is converted into secondary fiber, it is deinked. The output of some pulp mills is not used to make paper, but to produce cellulose acetate or to be dissolved and regenerated in the form of viscose fibers or cellophane. 

Dichloroisoviolanthrone was supplied by the pigment industry in the form of a pigment preparation, which was a specialty product for use in spin dyed viscose fibers. This pigment preparation has only recently been withdrawn from the market. The shade of P.V.31 is a reddish violet, which is distinctly redder than that of the known... 

With the exception of starch, many biopolymers cannot provide nutrition for humans and other omnivorous animals. In human foods biopolymers are used as additives that can improve texture, viscosity, fiber content, and other properties of prepared foods, without providing direct nutritional values. Examples of such utilization are the addition of pectins, agar, and other gums to foods to achieve thickening and gelling effects. Another example of potential large-scale utilization of cell wall biopolymers is the dramatic improvement in the texture and rising of breads prepared from com and other starches by the addition of xylans (78). 

Uses. Manufacture of rayon viscose fibers and cellophane film solvent for lipids, sulfur, rubber, phosphorus, oils, resins, and waxes insecticide... 

In the past, various resin flow models have been proposed [2,15-19], Two main approaches to predicting resin flow behavior in laminates have been suggested in the literature thus far. In the first case, Kardos et al. [2], Loos and Springer [15], Williams et al. [16], and Gutowski [17] assume that a pressure gradient develops in the laminate both in the vertical and horizontal directions. These approaches describe the resin flow in the laminate in terms of Darcy s Law for flow in porous media, which requires knowledge of the fiber network permeability and resin viscosity. Fiber network permeability is a function of fiber diameter, the porosity or void ratio of the porous medium, and the shape factor of the fibers. Viscosity of the resin is essentially a function of the extent of reaction and temperature. The second major approach is that of Lindt et al. [18] who use lubrication theory approximations to calculate the components of squeezing flow created by compaction of the plies. The first approach predicts consolidation of the plies from the top (bleeder surface) down, but the second assumes a plane of symmetry at the horizontal midplane of the laminate. Experimental evidence thus far [19] seems to support the Darcy s Law approach. 

Ashahi Chemical Industry Co., Ltd. Acrylonitrile polymerization or graft copolymerization in viscose, fibers. Japan Pat. 17,894 (1963), C. A. 60, 3154... 

Perform optimization of a process of radiation polymerization on fibers. The system response is homopolymer yield. The aim of optimization is to define conditions that facilitate obtaining more than 50% of homopolymer (with respect to fiber mass) on radiation polymerization of styrene, on the surface of viscose fibers. The process is defined by two factors ... 

The upper limit of the Newtonian plateau is dependent on Mw and the melt temperature. Commonly, it is roughly in the region y = 10 2s 1. Low viscosity fiber-forming Nylon and polyethylene terephthalate (PET) are important exceptions, as their Newtonian plateau extends to higher shear rates. 

Viscose or rayon A well-known inherently FR viscose fiber is Viscose FR, marketed by Lenzing. The fiber is produced by adding Sandoz 5060 (Clariant 5060)-bis(2-thio-5,5-dimethyl-l,3,2-dioxa-phosphorinyl)oxide in the spinning dope before extrusion. As this additive is phosphorus based, it is similar to other phosphorus-based FRs in terms of mode of action (condensed phase). 

In the past, various resin flow models have been proposed (2, 15-19). Two main approaches to predicting resin flow behavior in laminates have been suggested in the literature thus far. In the first case, Kardos et al.2), Loos and Springer15), Williams et al.16) and Gutowski17) assume that a pressure gradient develops in the laminate both in the vertical and horizontal directions. These approaches describe the resin flow in the laminate in terms of Darcy s Law for flow in porous media, which requires knowledge of the fiber network permeability and resin viscosity. Fiber... 

Alkali celluloses are extremely important intermediates because they exhibit a markedly enhanced reactivity compared with original cellulose. The reagents can penetrate more easily into the swollen cellulose structure and thus react with the hydroxyl groups. For instance, preparation of alkali cellulose, named mercerization after its inventor John Mercer (1844), is an important step when producing cellulose xanthate, from which viscose fibers and cellophane are prepared. 

Hollow viscose fibers contain gas pockets produced by adding blowing agents, such as sodium carbonate, to the viscose. When carbon dioxide is released during regeneration, the fibers inflate, leading to the formation of hollow filaments. The added free volume and decrease in molecular order, increase the ability of the fibers to pick up water. 

Typical reactions of CS2 are summarized in Figure 42. CS2 forms a range of metal complexes,making use of one, two, or all of its atoms (Figure 43). Commercially, the reaction with alcohol (cellulose) is used in the manufacture of viscose fiber this use, together with the preparation of CCI4, accounts for the majority of CS2 manufacture, with lesser... 

W s-Gubala, J., Machnowski, W. Application of Raman spectroscopy for differentiation among cotton and viscose fibers dyed with several dye classes. Spectrosc. Lett. 47(7), 527-535 (2014)... 

Non-woven swabs consist of a non-woven viscose fabric and are available in folded pieces of various dimensions. They have a lower total absorbent capacity than gauze but absorb more quickly because of the random orientation of the viscose fibers. As fabrics, they constitute the outer layer on a number of wound... 

The oldest and most widely practiced cellulose regeneration technology of the derivatizing solvent-type is the viscose rayon process. It is based, in part, on the discovery in 1857 by Cross, Bevin, and Beadle of the dissolution of sulfidized cellulose in alkali. Viscose fibers are by far the most important cellulose regenerates, amounting to an annual fiber production of 2.5 X 10 t worldwide [13,74]. 

Sodium sulfate is produced in large quantities as a byproduct in various chemical and metallurgical processes e.g. in the production of sodium dichromate, vitamin C, formic acid, resorcinol and viscose fibers. 

Figure 23>6 (a) 002 lattice fringes image on a cross section of a carbonized viscose fiber coated with pyrolytic carbon by CVD from propylene at 900°C. The continuous line shows the separation between a microporous carbon at the bottom (fiber) and the lamellar pyro-carbon at the top. The two insets represent a magnification of selected areas in these two parts, (b) Model showing the disordered nanotexture of the fiber and the lamellar and dense nanotexture of the coating. The coating acts as a barrier which hinders an easy diffusion of species to the core of the fiber. (Adapted from [22]). 

Diagram 2.2 to2.5 show diameter changes for polyester, acrylic, cotton and viscose rayon. It can be seen that with increasing the time of irradiation, the destruction of fibers increased significantly. For polyester, cotton and viscose fibers this destruction appears in the form of increase in the fiber diameter whilst for the acrylic fiber, this deformation appears as decrease of the fiber diameter. 

Diagram 2.5. Viscose fiber diameter change verses time after irradiation atl3000 x. 

Before discussing the mechanism of salt absorption by viscose fibers, it is perhaps desirable to consider the stability of the viscose monofils used. 

Considerable quantities of sodium sulfate and zinc sulfate are also formed f ri sg regeneration of cellulose fibers. Part of the sodium and zinc sulfates is discharged from the spinning bath together with the viscose fibers and enters the wastewater through the aftertreatment of the fibers. 

During spinning or extrusion, the macromolecules are oriented in the direction of flow to give high strength to the viscose fiber or the Cellophane film. The occurrence of macromolecular orienfafion during spinning is very important, and it is used in the chemical modification of many polymers. 

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. 

Cellulosic fibers are characterized by favorable properties such as renewability, biodegradability, environment friendly, excellent affinity for chemical functionalization as well as potential applicability [149]. Cellulosic fibers may be natural, such as cotton, flax, and jute, or regenerated fibers such as lyocell, using NMMO [N-methyl, morpholine-N-oxide] as a solvent for cellulose pulp, viscose, via, more environment-friendly viscose process, as well as bamhoo viscose fibers [24,142,149]. 

Lyocell fibers have outstanding properties. The main advantages of these fibers in comparison to viscose fibers are the following ... 

FIGURE 10.37 Fiber cross section of (a) Lyocell fiber and (b) Viscose fiber. (From Fink, H.P., Weigel, P., Purz, H.J., and Ganster, J., Prog. Polym. ScL, 26,1473,2001. Reprinted with permission of Elsevier B. V.)... 

---