Acrylic fibers Class

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. 

Basic dyes are die must popular class applied to acrylic fibers. Like nylon, acrylic can be dyed with disperse dyes, but with the same reservations of fastness. Disperse dyes are therefore only used for pale shades where excellent levelncss is needed or difficult to obtain by any other method owing to variations in the fiber... 

Disperse Dyes. These are substantially water-insoluble nonionic dyes for application to hydrophobic fibers from aqueous dispersion. They are used predominantly on polyester and to a lesser extent on nylon, cellulose, cellulose acetate, and acrylic fibers. Thermal transfer printing and dye diffusion thermal transfer (D2T2) processes for electronic photography represent niche markets for selected members of this class (see Chapter 6). 

Acrylics. Manufacturers of acrylic fibers have not generally published or confirmed the chemical composition of their fibers (116). Acrylic fiber will generally contain 85-94% acrylonitrile the balance is made up of comonomers having a specific function, such as to provide dye affinity for specific dye classes or to regulate diffusion of dye into the fiber. A list of typical comonomers has been published (116). Acrylic fibers may also contain heat (117) and light stabilizers (116). They may also contain a delustrant such as titanium dioxide. Some products contain optical brightening agents. These materials probably never exceed 4r-5% of the total composition. The cross-sectional shapes of the fibers vary (116). 

Benzodiazepines and 3//-1,5-benzodiazepines are important classes of compounds because of their interesting pharmacological properties. They show anticonvulsant, antianxiety, analgesic, sedative, antidepressive, hypnotic, antiinflammatory activity and also potent inhibitor of HIV-1 reverse transcriptase. Besides their biological relevance, benzodiazepines have also found application as dyes for acrylic fibers [163]. 

An interesting practical test concerning comfort of acrylic fibers has been reported recently A group of 69 basketball players were equipped with one or more socks made of acrylic fibers on one foot, and the same number of socks made of cotton or wool on the other. The class of fiber was not identified to the players. The result was that 59 out of the 69 athletes preferred the socks from acrylic fibers versus those from cotton or wool, because they kept their feet drier, and felt softer. 

Benzodiazepines are an important class of pharmacologically active compounds finding application as anticonvulsant, antianxiety, and hypnotic agents. Benzodiazepine derivatives also find commercial use as dyes for acrylic fibers and as anti-inflammatory agents. Jarikote and coworkers have developed a new and efficient method for the regioselective synthesis of 1,5-benzodiazepines in excellent isolated yields in short reaction times nsing a room-temperature ionic liquid, namely,... 

For other major apparel fibers such as wool, silk, and nylon a dye class referred to as acid dyes is routinely used for coloration. Reactive dyes have also been developed for wool and are widely used for fashion apparel items because of their bright, broad color range. A range of mordant dyes is also available for wool and other animal fibers. The mordant dyes provide very high levels of fastness, but the shade range is limited, the shades are typically dull, and the application process is complicated. For acrylic fibers the dominant dye class is the basic dye. For polyester apparel, the insoluble disperse dye range is almost exclusively used. 

The acrylic fibers exhibit the high strength, stiffness, toughness, abrasion resistance, resilience, and flex life that are associated with the synthetic fibers as a class. They are relatively insensitive to moisture and have good resistance to stains, chemicals, insects, and fungi. Their weatherability is outstandingly good. In continuous filament form, they are considered to have a superior feel. As crimped staple, they are noted for bulkiness and a wool-like hand. ... 

The nature and distribution of acrylonitrile and comonomer or comonomers in the acrylic fibers affect the overall dyeability and the classes of dyes that may be used in dyeing these fibers. Both acrylic and modacrylic fibers can be dyed using disperse dyes, with the more hydrophobic and less crystalline modacrylic being more dyeable with this dye class. The polar cyanide groups in the acrylonitrile unit of these fibers have some affinity for acid dyes and particularly mordanted systems containing copper or chromium ions. Addition of an acid or basic comonomer such as acrylic acid or vinyl pyridine as comonomer imparts improved dyeability with basic and acid dyes, respectively, for these fibers. Vat dyes can be used on acrylic fibers to a limited extent. 

The entire spectrum of inorganic fibers can be divided into two classes, based on differences in the crystallinity of the solids (Ray, 1978). Synthetic fibers have been known as man-made mineral fibers (MMMF) and manmade vitreous fibers (MMVF). But fibrous materials can be approached or divided in other ways. For example, in the Concise Encyclopedia of Chemical Technology (1985) the entry for chemical fibers includes both manmade and natural polymers, with the discussion centering on carbon-based compounds such as acetates, acrylics, and cellulose. Fibers of other inorganic compounds were not mentioned in the encyclopedia under this entry, but silica glass fibers were described under the heading Optical Fibers. ... 

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. 

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. 

Of the fibers listed in Table II only the polyesters, polyamides, spandexes, acetates, and rayon are discussed in this chapter. While the acrylics and modacrylics are the third most important class of commercial fibers because their polymerization chemistry is also discussed in other chapters concerned with vinyl addition emulsion polymerizations, it will only be briefly summarized here. For the same reason polypropylene polymerization chemistry is also not covered in this section. However, two additional topics, carbon fiber formation and polybenzimidazoles have been included on the basis of the current Interest in high-performance fibers for composite materials. 

Acrylated urethanes are an Important class of commercial radiation-curable oligomers. Industrial applications of these materials cover a wide range. Including binders for magnetic media, vehicles for inks, and coatings for vinyl floor tiles, optical fibers, and paper. The compositions, and therefore, the properties of the acrylated urethanes are varied in order to meet the performance criteria of the different end uses. Properties of various acrylated urethanes will be discussed as they relate to structure. 

The synthetic fiber Industry is only about fifty years old yet the annual production Is In billions of lbs. The development of fibers resulted due to advances In polymer synthesis and new spinning methods. At the present time nylons, polyesters, acrylics and polyolefins are major classes of synthetic fibers. Fibers have also been made from polymers, e.g., polyvinylIdene chloride and polyvinyl alcohol but their commercialization has not materialized. Recently, we have made fibers from fluorenone polyesters which have good potentials and should be further developed. 

Several classes of polymeric materials are found to perform adequately for blood processing, including cellulose and cellulose esters, polyamides, polysulfone, and some acrylic and polycarbonate copolymers. However, commercial cellulose, used for the first membranes in the late 1940 s, remains the principal material in which hemodialysis membranes are made. Membranes are obtained by casting or spinning a dope mixture of cellulose dissolved in cuprammonium solution or by deacetylating cellulose acetate hollow fibers [121]. However, polycarbonate-polyether (PC-PE) block copolymers, in which the ratio between hydrophobic PC and hydrophilic PE blocks can be varied to modulate the mechanical properties as well as the diffusivity and permeability of the membrane, compete with cellulose in the hemodialysis market. 

This method of analysis is suitable for fiber identification, as well as for characterization of any chemical differences between two fibers of the same class. For instance, acrylic and modacrylic fibers containing copolymers of varying constitution and proportion may be identified. Identification depends on matching the additional bands with those in the IR spectrum of a fiber whose identity is already known. Both the wavelength and intensity differences of bands in each spectrum must be taken into account. Fiber samples may be prepared in the form of a pressed disk, where very finely divided particles of the fiber are uniformly distributed in powdered po-tassiiun bromide. The mixture is pressed into a small disk of about 1 mm thickness in a vacuum die vmder... 

Acrylic o- kri-lik [ISV acrokein + -yl + -ic] (1855) adj. (1) The generic class of polymers and monomers (appox. 1942) derived from acrylic acid including polymethyl methacrylate. (2) Generic name for fibers... 

Dyes, basic n. A class of positive-ion-carrying dyes known for their brilliant hues. Basic dyes are composed of large-molecule, water-soluble salts that have a direct affinity for wool and silk and can be applied to cotton with a mordant. The fastness of basic dyes on these fibers is very poor. Basic dyes are also used on basic-dyeable acrylics, modacrylics, nylons, and polyesters, on which they exhibit reasonably good fastness. 

Manufactured fiber n. A class name for various genera of fibers (including filaments) produced from fiber-forming substances which may be (1) Polymers synthesized from chemical compounds, e.g., acrylic, nylon, polyester, polyethylene, polyurethane, and... 

Synthetic fiber (man-made fiber) n. A class name for various fibers (including filaments), distinguished from natural fibers such as wool and cotton, produced from fiber-forming substances which may be (1) Modified or transformed natural polymer, e.g., alginic and cellulose-based fibers such as acetates and rayon s. (2) Polymers synthesized from chemical compounds, e.g., acrylic, nylon, polyester, polyurethane, polyethylene, polyvinyl, and carbon/graphite fibers. (3) Fibers of mineral origin, e.g., glass, quartz, boron, and alumina. 

Another way to classify polymers results from the consideration of their typical applications. Typical classes are Compression molding compounds, injection molding compounds, semi-finished products, films, fibers, foams (urethane foam, styrofoam), adhesives (synthetic adhesives are based on elastomers, thermoplastics, emulsions, and thermosets. Examples of thermosetting adhesives are Epoxy, polyurethane, cyanoacrylate, acrylic polymers), coatings, membranes, ion exchangers, resins (polyester resin, epoxy resin, vinylether resin), thermosets (polymer material that irreversibly cures), elastomers (BR, silicon rubber). 

Acrylic polyesters are also used by the polymer industry to produce fibers. However, the blends and composites of this class of polymers with conductive polymers were systematically prepared in the form of films One of the first attempts involved the electrochemical polymerization of 3-methylthiophene using an electrolyte solution containing poly(methyl methacrylate) [92]. By this method poly(methyl methacrylate) is codeposited on the electrode with the conductive polymer, forming a self-supported film. The conductivity of the film on the electrode side was two orders of magnitude higher than on the electrolyte side. Cyclic voltammetry and the visible spectra of the blend reproduce exactly the curves for the pure conductive polymer. This one-step synthesis is an alternative to the electrode coating method, provided that the insulating polymer host is soluble in the electrolyte solution. 

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