Fiber developments synthetic fibers

The articles outlined the significance of this work how countries under the spur of national defense needed to develop synthetic fibers so that they might be liberated from foreign imports that might fail in time of war yet not exhaust their own natural resources. 

Du Pont was particularly interested in developing synthetic fibers. Because of political and trade problems resulting from Japan s war in China, the United States s main source of silk was restricted, so work was directed toward producing an artificial substitute. Carothers believed that polycondensation, in which polymers are formed by condensation and the elimination of small molecules such as water, would yield interesting new materials. His work with dibasic acids (acids with two hydrogen atoms, such as sulfuric acid [H2SO4]) and dihydroxy compounds (compounds with two OH-ions, such as tartaric acid [2,3-dihydrobutanedioic acid] produced different... 

Figure 15 demonstrates that developing synthetic fiber cords for high lift conveyor belts will offer a solution with 2 x 1000 m, 2400 DS16000 10000 t/h. 

As reviewed in this chapter, for lignocellulosic fibers, the development of stronger interfaces with polymeric matrices has already given the first steps. The world expectation that natural materials assume a greater participation in industrialized products is a motivation for future works on the possibility of lignocellulosic fibers replacing synthetic fibers in polymer composites. With improved IFSS, this will certainly become a reality and hopefully will contribute to the quality of our environment. 

A study on hybrid composites of sisal fiber with other natural fibers or synthetic fiber is needed to achieve optimum benefit for broader applications. Sisal fiber/ matrix interface and relationship between interface and bulk composites need to be studied in detail for a better understanding leading to the development of a unique process for better bonding between fiber and matrix and compatibility with a wider range of other materials/components. Further R D, new initiatives, and innovation are needed to develop a unique mechanism for the manufacture of environmental... 

Fibrous superabsorbent polymers have larger surface areas than particulate ones. Furthermore, they have excellent diffusion and permeation of liquid by capillary effect and thus high absorbencies are expected. These fibers can be manufactured with ordinary structural fibers such as cellulose fibers or synthetic fibers by the airlaid technique, and the potential for further development is high. 

Many manufactured protein fibers were commercialized in mid-twentieth century. However, due to technical and economic problems, manufactured protein fibers were not able to compete with either natural fibers or the newly development synthetic fibers at that time. All manufactured protein fibers developed in mid-twentieth century eventually were abandoned by manufacturers. 

The use of 2-aminothiazole derivatives as dyeing compounds is direct related to the development of synthetic fibers. Some typical examples are given in Table VI-14. The importance of these dyes lies in their performance on acetate fibers. They have excellent fastness to gas fumes, produce a bright blue shade, and have a high tinctorial strength. Their only disadvantage is their relatively low light fastness, which does limit their application. 

Acrylonitrile (AN), C H N, first became an important polymeric building block in the 1940s. Although it had been discovered in 1893 (1), its unique properties were not realized until the development of nitrile mbbers during World War II (see Elastomers, synthetic, nitrile rubber) and the discovery of solvents for the homopolymer with resultant fiber appHcations (see Fibers, acrylic) for textiles and carbon fibers. As a comonomer, acrylonitrile (qv) contributes hardness, rigidity, solvent and light resistance, gas impermeabiUty, and the abiUty to orient. These properties have led to many copolymer apphcation developments since 1950. 

Asahi Chemical Industries (ACl, Japan) are now the leading producers of cuprammonium rayon. In 1990 they made 28,000 t/yr of filament and spunbond nonwoven from cotton ceUulose (65). Their continuing success with a process which has suffered intense competition from the cheaper viscose and synthetic fibers owes much to their developments of high speed spinning technology and of efficient copper recovery systems. Bemberg SpA in Italy, the only other producer of cuprammonium textile fibers, was making about 2000 t of filament yam in 1990. 

Considerable effort is being made (ca 1993) to develop satisfactory flame retardants for blended fabrics. It has been feasible for a number of years to produce flame-resistant blended fabrics provided that they contain about 65% or more ceUulosic fibers. It appears probable that blends of even greater synthetic fiber content can be effectively made flame resistant. An alternative approach may be to first produce flame-resistant thermoplastic fibers by altering the chemical stmcture of the polymers. These flame-resistant fibers could then be blended with cotton or rayon and the blend treated with an appropriate flame retardant for the ceUulose, thereby producing a flame-resistant fabric. Several noteworthy finishes have been reported since the early 1970s. 

A further development in the coumarin series is the use of derivatives of 3-phenyl-7-aminocoumarin ((13) where R, R = Cl or substituted amines) as building blocks for a series of light-stable brighteners for various plastics and synthetic fibers, and, as the quatemi2ed compounds, for brightening polyacrylonitrile (62). 

Dry-Laid Pulp. A principal objective of using air to form webs from natural and synthetic fiber pulps is to produce relatively lofty, porous stmctures from short fibers, without using water. Early technical developments in air-laid pulp processing were made by Kroyer in Denmark. 

Dyestuffs. The use of thiophene-based dyestuffs has been largely the result of the access of 2-amino-3-substituted thiophenes via new cycHzation chemistry techniques (61). Intermediates of type (8) are available from development of this work. Such intermediates act as the azo-component and, when coupled with pyrazolones, aminopyrazoles, phenols, 2,6-dihydropyridines, etc, have produced numerous monoazo disperse dyes. These dyes impart yeUow—green, red—green, or violet—green colorations to synthetic fibers, with exceUent fastness to light as weU as to wet- and dry-heat treatments (62-64). 

The appearance of synthetic fibers in the 1920s accelerated the further development of anthraquinone dyes. Soon after British Celanese succeeded in commerciali2ing cellulose acetate fiber in 1921, anthraquinone disperse dyes for this fiber were invented by Stepherdson (British Dyestuffs Corp.) and Celatenes (Scottish Dyes) independendy. Anthraquinone disperse dyes for polyester fiber were developed after the introduction of this fiber by ICI and Du Pont in 1952. These dyes were improved products of the disperse dyes that had been developed for cellulose acetate fiber 30 years before. 

Because of their inherently high efficiency on dusts in all particle-size ranges, fabric filters have been used for collection of fine dusts and fumes for over 100 years. The greatest limitation on filter application has been imposed by the temperature limits of available fabric materials. The upper limit for natural fibers is about 90°C (200°F). The major new developments in filter technology that have been made since 1945 have followed the development of fabrics made from glass and synthetic fibers, which has extended the temperature limits to about 230 to 260°C (450 to 500°F). The capabihties of available fibers to resist high temperatures are still among the most severe limitations on the possible applications of fabric filters. 

Acetate rayon dyes developed for cellulose acetate and some synthetic fibers. 

Polyamides are the second largest group of synthetic fibers after polyesters. However, they were the first synthetic fibers that appeared in the market in 1940. This was the result of the work of W. H. Carothers in USA who developed nylon 66. At about the same time nylon 6 was also developed in Germany by I. G. Farben. Both of these nylons still dominate the market for polyamides. However, due to patent restrictions and raw materials considerations, nylon 66 is most extensively produced in USA and nylon 6 is most extensively produced in Europe. 

Acrylic fibers are a major synthetic fiber class developed about the same time as polyesters. Modacrylic fibers are copolymers containing between 35-85% acrylonitrile. Acrylic fibers contain at least 85% acrylonitrile. Orion is an acrylic fiber developed by DuPont in 1949 Dynel is a modacrylic fiber developed by Union Carbide in 1951. 

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