Acrylics textile fibers

The one step process for the fabrication of pure silica sliver from sodium silicate [1-3] is an adaptation oil the generic dry spinning process that has been practiced for over 50 years in the fabrication of polymer organic textile fibers. Acrylic polymers, unlike polyesters or nylons, are infusible and cannot be melt spun. They can be dry or wet spun from viscous solutions. The model for inorganic dry spinning processes is the dry spinning process by means of which acrylic fibers such as Orion, are spun using dimethyl formamide as the solvent (Table I). 

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. 

Uses. The largest use for sodium thiocyanate is as the 50—60 wt % aqueous solution, as a component of the spinning solvent for acryUc fibers (see Fibers, acrylic Acrylonitrile polymers). Other textile appHcations are as a fiber swelling agent and as a dyeing and printing assist. A newer commercial use for sodium thiocyanate is as an additive to cement in order to impart early strength to concrete (376). 

Other textile fibers include nylon, polyacrylonitrile, and ceUulose acetate (see Fibers, acrylic Fibers, cellulose esters Fibers, polyamide). 

Acrylic Plastics 1931 G P P F-P F-P Injection, compression, extrusion or blow molded Lenses, aircraft and building glazing, lighting fixtures, coatings, textile fibers... 

Acrylic textile fibers are primarily polymers of acrylonitrile. It is copolymerized with styrene and butadiene to make moldable plastics known as SA and ABS resins, respectively. Solutia and others electrolytically dimerize it to adiponitrile, a compound used to make a nylon intermediate. Reaction with water produces a chemical (acrylamide), which is an intermediate for the production of polyacrylamide used in water treatment and oil recovery. 

The principal use of acrylonitrile since the early 1950s has been in the manufacture of so-called acrylic textile fibers. Acrylonitrile is first polymerized to polyacrylonitrile, which is then spun into fiber. The main feature of acrylic fibers is their wool-like characteristic, making them desirable for socks, sweaters, and other types of apparel. However, as with all synthetic textile fibers, fashion dictates the market and acrylic fibers currently seem to be in disfavor, so this outlet for acrylonitrile may be stagnant or declining. The other big uses for acrylonitrile are in copolymers, mainly with styrene. Such copolymers are very useful for the molding of plastic articles with very high impact resistance. 

Random copolymerization of one or more additional monomers into the backbone of PET is a traditional approach to reducing crystallinity slightly (to increase dye uptake in textile fibers) or even to render the copolymer completely amorphous under normal processing and use conditions (to compete with polycarbonate, cellulose propionate and acrylics in clear, injection molded or extruded objects). 

Table 10.2 outlines the uses of acrylonitrile. One important use of acrylonitrile is in the polymerization to polyacrylonitrile. This substance and its copolymers make good synthetic fibers for the textile industry. Acrylic is the fourth largest produced synthetic fiber behind polyester, nylon, and... 

Basic (Cationic) Dyes. The use of basic dyes is confined mainly to acrylic textile fibers, acetate, and as complementary dyes for acid-modified polyester libers that accept this class of dyes. 

Esters of acrylic acid (acrylates) are used for manufacture of coatings, textiles, fibers, polishes, paper, and leather. 

Acrylic acid is almost exclusively used directly, or after conversion to an ester, as a monomer. Acrylate esters are produced by normal esterification processes. However, in dealing with acrylic acid, acrolein, or acrylates, unusual care must be taken to minimize losses due to polymerization and other side reactions such as additions of water, acids, or alcohols across the reactive double bond. Polyacrylic acids find use in superabsorbers, dispersants, and water treatment. The polyesters are used in surface coatings, textile fibers, adhesives, and various other applications. 

Rhizopus miehei Poly(methyl acrylate) Textile fibers Inprakhon and... 

The world textile industry is one of the largest consumers of dyestuffs. An understanding of the chemistry of textile fibers is necessary to select an appropriate dye from each of the several dye classes so that the textile product requirements for proper shade, fastness, and economics are achieved. The properties of some of the more commercially important natural and synthetic fibers are briefly discussed in this section. The natural fibers may be from plant sources (such as cotton and flax), animal sources (such as wool and silk), or chemically modified natural materials (such as rayon and acetate fibers). The synthetic fibers include nylon, polyester, acrylics, polyolefins, and spindex. The various types of fiber along with the type of dye needed are summarized in Table 8.2. 

Another property used to compare the flammability of textile fibers is the limiting oxygen index (LOI). This measurement quantity describes the minimum oxygen content (%) in nitrogen necessary to sustain candle-like burning. Values of LOI, considered a measure of the intrinsic flammability of a fiber, are listed in Table 12.28 in order of decreasing flammability. Acrylic fibers, it can be seen, are similar in flammability to cotton. Modacrylics, on the other hand, are somewhat less flammable than any of the synthetics, except 100% PVC, and are substantially less flammable than cotton and wool. 

Polymeric materials then, whether natural (such as cellulose, resins, and proteins) or synthetic (such as polyolefins, nylons, and acrylics), behave in reproducible ways when exposed to pyrolysis temperatures. This permits the use of pyrolysis as a sample preparation technique to allow the analysis of complex materials using routine laboratory instruments. Pyrolytic devices may now be interfaced easily to gas chromatographs, mass spectrometers, and FT-IR spectrometers, extending their use to solid, opaque, and multicomponent materials. Laboratories have long made use of pyrolysis for the analysis of paint flakes, textile fibers, and natural and synthetic rubber and adhesives. The list of applications has been expanded to include documents, artwork, biological materials, antiquities, and other complex systems that may be analyzed with or without the separation of various layers and components involved. 

Acrylic precursors for the carbon fiber industry originated from companies that were established commercial scale producers of textile grade acrylic fibers. Hence, the manufacturers that could most readily adapt their existing technology to create a precursor grade material have been most successful (Table 4.2). However, some aspects such as dyeability and a tendency to yellow are not important parameters for a carbon fiber precursor but, because that particular polymer formulation was initially used for other textile end uses, the polymer composition could not be changed. As carbon fibers have developed, the market requirement for suitable precursors has increased and new polymers have been developed specifically for the manufacture of carbon fibers. 

If acrylic textile fiber continues to be available and can be successfully converted to LCCF, then thermoformable acrylic pol5uners will not be favored, unless the sale price of the resin is less than 1 per kg. This may encourage capital investment for new precursor forms. 

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