Textile acrylic

Figure 6. Carbon footprint of cotton textiles with yarn thickness comprised between 70 and 300 dtex (left) and synthetic textiles - acryl, nylon, PET, elastane-, with yarn thickness of 70 dtex (right) [59]...

Figure 3.12 Variation of carbon fiber composite flexural modulus with heat treatment temperature. Source Reprinted with permission from Hornby J, Kearsey HA, Sharps JW, The preparation of carbon fibres from large-tow textile acrylic fibre 5. Continuous heat-treatment at temperatures to 2600°C, AERE-R 8867, United Kingdom Atomic Energy Authority, Harwell, Jan 1978. Copright 1978, AEA Technology pic.

Hornby J, Kearsey HA, The preparation of carbon fibres from large-tow textile acrylic fibre 4. Comparison of different precursors, AERE-R 8865, United Kingdom Atomic Energy Authority,... 

Not many textile acrylic fiber production facilities provide a product suitable for use as precursor to make a satisfactory carbon fiber. The major producers of PAN precursor carbon fiber are listed in Table 5.5. 

Filament textile acrylics seem to have lost the competition with polyester and nylon. 

Most textile acrylics contain 10-15% comonomers. For carbon fiber precursors lower comonomer levels are used (about 5%) comonomers are selected that promote the reactions in the aftertreatment (methyl acrylate, itaconic acid). Wet spinning is preferred because the cross-section can be controlled better then. In dry spinning skin formation can hardly be prevented and eventually the cross-section collapses into a "dog bone shape, which is not desirable in carbon fiber applications. Precursor filaments are drawn to much higher draw ratios (> lOx) than tex-... 

High strength acrylic fibres have been developed with a modulus of elasticity in the range of 14-25 GPa, and tensile strengths up to 1000 MPa [124-126] that is, the modulus of elasticity is of the same order of magnitude as that of the matrix. The fibres can be produced in the form of discrete short filaments, and can also be woven into various fabrics. The stress-strain curves of these fibres are shown in Figure 10.35, where they are compared with conventional textile acrylic fibres. The increases in tensile strength and modulus of elasticity relative to the textile... 

Figure 10.35 Stress-strain curves of aery lie fibres developed for cement reinfored-cement (Dolanit-D-10 D-VFI I) and conventional textile acrylic fibres (after Hahne etal. [126]).

Acrylates are primarily used to prepare emulsion and solution polymers. The emulsion polymerization process provides high yields of polymers in a form suitable for a variety of appHcations. Acrylate polymer emulsions were first used as coatings for leather in the eady 1930s and have found wide utiHty as coatings, finishes, and binders for leather, textiles, and paper. Acrylate emulsions are used in the preparation of both interior and exterior paints, door poHshes, and adhesives. Solution polymers of acrylates, frequentiy with minor concentrations of other monomers, are employed in the preparation of industrial coatings. Polymers of acryHc acid can be used as superabsorbents in disposable diapers, as well as in formulation of superior, reduced-phosphate-level detergents. 

Emulsion Polymerization. Emulsion polymerization is the most important industrial method for the preparation of acryhc polymers. The principal markets for aqueous dispersion polymers made by emulsion polymerization of acryhc esters are the paint, paper, adhesives, textile, floor pohsh, and leather industries, where they are used principally as coatings or binders. Copolymers of either ethyl acrylate or butyl acrylate with methyl methacrylate are most common. 

Synthetic emulsion polymers account for approximately 70% of the U.S. consumption of acrylate monomers. Major end uses for these latex polymers are coatings (32%), textiles (17%), adhesives (7%), paper (5%), and floor poHshes (3%). The U.S. producers of acryflc copolymer emulsions include Rohm and Haas, Reichhold, National Starch, Union Carbide, Air Products, Unocal, B. F. Goodrich, and H. B. Fuller. 

Another textile use of acryUc polymers is fabric finishing, to impart a desired hand or feel, or to aid soil release, or for permanent-press features. Copolymers of acrylate esters with acryUc or methacrylic acid serve as thickeners for a variety of textile coating formulations (see Textiles, finishing). 

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. 

Functional derivatives of polyethylene, particularly poly(vinyl alcohol) and poly(acryLic acid) and derivatives, have received attention because of their water-solubility and disposal iato the aqueous environment. Poly(vinyl alcohol) is used ia a wide variety of appHcations, including textiles, paper, plastic films, etc, and poly(acryLic acid) is widely used ia detergents as a builder, a super-absorbent for diapers and feminine hygiene products, for water treatment, ia thickeners, as pigment dispersant, etc (see Vinyl polymers, vinyl alcohol polymers). 

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). 

The largest volume commercial derivatives of 1-butanol are -butyl acrylate [141-32-2] and methacrylate [97-88-1] (10). These are used principally ia emulsion polymers for latex paints, ia textile appHcations and ia impact modifiers for rigid poly(vinyl chloride). The consumption of / -butanol ia the United States for acrylate and methacrylate esters is expected to rise to 182,000—186,000 t by 1993 (10). 

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

Poly(methyl acrylate) is water-sensitive and, unlike the corresponding methacrylate, is attacked by alkalis. This polymer and some of the lower acrylate polymers are used in leather finishing and as a textile size. 

A number of higher poly(vinyl ether)s, in particular the ethyl and butyl polymers, have found use as adhesives. When antioxidants are incorporated, pressure-sensitive adhesive tapes from poly(vinyl ethyl ether) are said to have twice the shelf life of similar tapes from natural rubber. Copolymers of vinyl isobutyl ether with methyl acrylate and ethyl acrylate (Acronal series) and with vinyl chloride have been commercially marketed. The first two products have been used as adhesives and impregnating agents for textile, paper and leather whilst the latter (Vinoflex MP 400) has found use in surface coatings. 

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. 

HPLC-UV is a popular technique to analyse textile dyes extracted from polyester fibres [697], acidic dyes from wool fibres [698] and basic dyes from acrylic fibres [699]. HPLC provides better sensitivity and resolution than TLC [697-699]. GE-RPLC has been used for the determination of 18 disperse dyes (e.g. Navy D-2G-133, Orange CB, Yellow D-3R and Red D-2G) extracted from polyester [700]. Compared with the traditional TLC method, HPLC offers lower detection limits, better observation of contaminant peaks, and reproducible quantitative results. HPLC has also been used to determine azo dyes [701,702]. 

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