Speciality rayons

Modified (special) rayons Flame-retardant rayons High absorbency (alloy rayons)... 

Higashi T, Toyama T, Sakurai H, et al. 1983. Cross sectional study of respiratory symptoms and pulmonary functions in rayon textile workers with special reference to hydrogen sulfide exposure. Ind Health 21 281-292. 

The surface properties of carbon fibers are intimately related to the internal structure of the fiber itself, which needs to be understood if the surface properties are to be modified for specific end applications. Carbon fibers have been made from a number of different precursors, including polyacrylonitrile (PAN), rayon (cellulose) and mesophase pitch. The majority of commercial carbon fibers currently produced are based on PAN, while those based on rayon and pitch are produced in very limited quantities for special applications. Therefore, the discussion of fiber surface treatments in this section is mostly related to PAN-based carbon fibers, unless otherwise specified. 

Geometric effects coupled with diffusion and nucleation usually control the rates of all solids deposition phenomena. Such effects can be put to good use in the production of special products such as cellulose yarn (rayon), by the precipitation of cellulose in filament form as it emerges as sodium cellulose xanthate liquid from the spinnerets into a bath containing sulphuric acid, which extracts the sodium as sodium sulphate, and the carbon disulphide. In a similar manner, the fabrication of aromatic polyimide fibres is performed by dissolving the polymer in concentrated sulphuric acid and forcing the solution through spinnerets into water. 

Amor age des polymerisations par les rayons y. Special issue of the collection of Czechoslovak Chemical Communications 22, 141—152 (1957). 

During preceding decades, the discovery of new products such as Bakelite, nylon, rayon, celluloid, polyvinyl chloride, polyethylene, Saran , and Teflon convinced chemical corporations that such products held the key to an exciting and profitable future based on a host of amazing new "miracle" materials. Research departments around the world began the search for new materials with properties designed to meet a variety of special needs. One chemist who succeeded in this kind of project was Stephanie Kwolek. 

Hunlich, R. (1939). Textile Fibres and Materials Their Properties and Identification with Special Reference to Rayon and Staple Fibre. London Skinner. 

This work was supported by organized research funds of the School of Textiles, North Carolina State University. The rayon fiber sample used for grafting was specially manufactured and supplied by Dr. Tom Allen of the American Enka Company. The authors gratefully acknowledge their assistances. 

Defatted jute was prepared by treating it with alcohol-benzene (1 2v/v) mixture in a Soxhlet apparatus, washed well with alcohol and air dried. Bleaching of jute fiber was carried out with 0.7% sodium chlorite following a special method (17) KPM rayon sample was prepared by treating it with dilute soap solution, washed well and dried. 

Thus Courtaulds withdrew from polyester and from Nylon to concentrate on its acrylics and cellulose fibers ICI focused on Nylon and Bayer on acrylics Rhone-Poulenc withdrew from acrylics but revamped its Nylon and polyester units well-integrated in upstream intermediates Montedison decided in favor of polyester and acrylics AKZO focused on polyesters and on aramide fibers while keeping up its profitable rayon sector. Such efforts, which aimed to reduce European chemical fiber capacities by 900,000 tons and to increase productivity through specialization, undoubtedly corrected the situation. 

Artificial silk was first produced from cotton waste in the early 1900s. Three Englishmen are credited with discovering how to produce viscose (rayon) from a cellulose solution using wood and woody materials. During World War I, this process was used to make guncotton (by nitrating the cellulose) and other explosives. The rayon was also used as artificial silk. Special dyes, now known as acid dyes, had to be developed to color this product. 

The various TEX-WETS are colloidal aqueous silica dispersions widely used in textile finishing to control yarn slippage, modify hand, and control luster. However applied, these products can be used to stabilize weave and to impart special finish effects to fabrics made of cotton, wool, synthetic fibers and filaments, and to mixtures. Treatment gives outstanding finishes on nylon and Dacron marquisettes, rayon fabrics and viscose rayon suitings. Application requires no special equipment nor curing. The dispersions are not cationic and, therefore, cannot be applied by exhaustion onto the fabric. 

There have been many attempts to utilize the approximately 1.8 V generated by the electrochemical reactions of the decomposer. Elowever, it has not been found possible to do this and to maintain high concentrations of sodium hydroxide and low residual sodium in the stripped mercury. The sodium hydroxide product obtained from the decomposer of a mercury cell is very pure, containing 0.001% or less sodium chloride. This product is referred to as rayon grade caustic because the high purity and low sodium chloride content makes it particularly suitable for rayon manufacture. This is achieved without the special purification steps required for the diaphragm cell product. 

The use of vat dyes in pigment form for cheeses and rayon cakes suggested improved techniques for various continuous and semi-continuous padding methods for the application of vat dyes to piece goods. Most vat dyes are now marketed in forms specially prepared to yield relatively stable dispersions of extremely finely-divided particles required for pigmentation. Fhe earliest and simplest procedure was the so-called pigment-pad process illustrated diagrammatically in Fig. 20.3 Ciba review. No. 120). In this case... 

Rayon and Acetate, A Special Report" in Rayonier Stamford, Conn., 1979. 

Du Font s major contribution to the country s war effort in World War 1 was the manufacture of explosives. By the time World War 11 erupted, explosives was just one of the many Du Pont products needed in the war effort. The insatiable appetite of the war machine imposed numerous demands on technical personnel to build new process lines (over 50 plants were built) in record time and to develop specialty products by yesterday. Chemical engineers played a key role in meeting these demands. Since natural rubber was no longer available, plants to manufacture synthetic rubber such as neoprene had to be built. Rayon and nylon were used in tire cord. Industries producing combat equipment needed heavy chemicals. The emergence of air power required special chemical materials such as plastic enclosures. 

The most commonly used method is called core spinning, in which staple fibers are wrapped around a hidden core. It produces chunky novelty yam, although the end weight of the yam depends on the core material used. The elastic fiber is used as core, which is wrapped with other fibers such as nylon, rayon, and cotton. It can be produced on regular ring spinning machines with special feeder rollers and guiding devices (Senthilkumar et ah, 2011). 

In the period 1965-1980 a wide variety of new, stronger, and more durable rayon fibers were developed. Rayon variants are now produced which utilize the comfort and aesthetic qualities of cellulose to compliment synthetic fibers in many textile applications. Considerable emphasis has been placed on the economics and ways to meet environmental and safety standards. Special effects, such as crimp or hollow filaments, may be obtained by appropriate viscose formulations, point-of-stretch applications, spin-bath compositions, and modifiers. Flame-retardant (FR), acid-dyeable, and superabsorbent rayons are typical of the properties that can be attained by incorporating various materials in the fiber structure. Rayon is unique in the respect that the fiber can be permanently modified for a wide variety of end uses simply by adding the appropriate material to viscose. 

Another way to achieve rapid depolymerization is to irradiate the cellulose with a beam of accelerated electrons [146-148]. In this case, the time required for the depolymerization is of the order of seconds. This technology has been investigated as a means to eliminate the need to age alkali cellulose in the viscose process, and rayon has been successfully made from irradiated pulp [149,150]. The process, however, has not been adopted by the industry because, like double steeping, material handling poses special requirements. 

Continuous-filament textile rayon, produced from viscose, while representing only a fraction of the world s total rayon production, is still an important article of commerce. Although its strength is on the low side, especially when wet, its other aesthetic properties make it unique for certain specialty end uses. Of special appeal is lightweight, sheer, richly colored textiles that are both comfortable and attractive. Coat hnings are a major market. 

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