Elastomeric fibers processing

Solvent Resistance. Elastomeric fibers tend to swell in certain organic solvents mbber fibers swell in hydrocarbon solvents such as hexane. Spandex fibers become highly swollen in chlorinated solvents such as tetrachloroethylene [127-18-4] (Perclene). Although the physical properties of spandex fibers return to normal after the solvent evaporates, considerable amounts of its stabilizers may have been extracted. Therefore, the development of stabilizers that are more resistant to solvent extraction has become important as solvent scouring during mill processing replaces aqueous scouring at many mills, especially in Europe (26). 

Elastomeric Fibers. Elastomeric fibers are polyurethanes combiaed with other nonelastic fibers to produce fabrics with controlled elasticity (see Fibers, elastomeric). Processing chemicals must be carefully selected to protect all fibers present ia the blend. Prior to scouriag, the fabrics are normally steamed to relax uneven tensions placed on the fibers duriag weaving. Scouriag, which is used to remove lubricants and siting, is normally conducted with aqueous solutions of synthetic detergents and tetrasodium pyrophosphate, with aqueous emulsions of perchloroethylene or with mineral spidts and sodium pyrophosphate. 

Elastomeric Fibers. Elastomeric fibers are polyurethanes combined with other nonelastic fibers to produce fabrics with controlled elasticity. See also Fibers Elastomeric. Processing chemicals must be carefully selected to protect all fibers present in the blend. 

Elastomeric polyurethane fibers [96, pp. 609-615], are contained in stretch articles and in knitted fashion materials. Light shades can be dyed tone-on-tone on polyamide-polyurethane mixtures with disperse dyes at 95-98°C and pH 6-7. However, the wetfastness of these dyeings on polyurethanes is lower than on polyamide. Because of the temperature sensitivity of polyurethane fibers, mixtures of elastomeric and polyester fibers must be dyed with small-molecular, rapidly diffusing disperse dyes in 30 min at 120 °C according to the HT process [148], Modified PES fibers that are dyeable at 100°C without a carrier are often used in mixtures with elastomeric fibers. In all dyeing processes for elastomeric fibers, dyeing equipment that permits low-strain guidance of the material and the lowest possible thermal stress are important. 

PCHE-containing block copolymers have been reported to have utility as melt spun elastomeric fibers [82]. The improved melt processability of these materials (compared with partially saturated block copolymers) allows them to be processed into small denier fibers with excellent tenacity and ultimate elongation. 

Mixtures of isocyanates are commonly used for convenience in commercial production of the diisocyanate, since the pure toluene 2,4-diisocyanate is more expensive to produce. The resulting prepolymer is then mixed with either a glycol, such as 1,6-hexanediol, or a deactivated (sterically hindered) diamine plus pigment if required, and then promptly poured into a preheated mold of the desired shape. In about half an hour the mixture sets to a pliable shape with stiffness and elasticity controlled by the components and processing details used [29]. Similar procedures produce high-strength polyurethane fiber (e.g., Perlon U) or elastomeric fibers (e.g., Spandex and Lycra). 

OTHER COMMENTS used as an intermediate in the preparation of polyurethane foams, elastomeric fibers, and polyamides used in industry as a curing agent for epoxy resins and urethane elastomers, and as a corrosion inhibitor for iron useful in the determination of tungsten and sulfates has also been used in the preparation of azo dyes, as a rubber processing chemical, and as an epoxy resin hardening agent. 

These covered yams consist of elastomeric multifilament yam and a covering made from conventional (hard) multifilament yams or fibers such as polyamide, viscose, and so forth (Petmlis, 2004). In this process, the elastomeric fiber, drawn at a constant factor, is fed through a hollow spindle and covered with a covering yam from a flanged bobbin. The produced yam has a particular differential-twist stracture, caused by the different twists and twist directions between the wrapping yam and the core yam. 

Core yam and cover yam with elastomeric fiber as the core shows lower elongation than that of the fiber itself. Usually, the draw ratio of the elastomeric fiber is from 2 to less than 4 when spinning as a core yam. Even with the elongation decrease, other mechanical properties have been improved such as tenacity, antifriction, hand feeling, and other functions such as moisture management. The elastomeric yams greatly increase the process ability and wearability of bare elastomeric fiber itself. These yams also are another important basis for functional sportswear design besides the elastomeric fibers. 

Acrylic ester homopolymers or statistical copolymers, whose annual world production is higher than 1 million tons, are used in the fields of paints in emulsion, adhesives, textile fiber processing, and paper industry. These applications are in close relationship with their glass transition temperature, which is relatively low. Poly(methyl acrylate) is much more stable against hydrolytic attack by acids and bases than its isomer poly(vinyl acetate). The poly(butyl acrylate) exhibits an elastomeric character which induces multiple applications. 

The late 1950s saw the emergence of cast elastomers, which led to the development of reaction injection mol ding (RIM) at Bayer AG in Leverkusen, Germany, in 1964 (see Plastics processing). Also, thermoplastic polyurethane elastomers (TPUs) and Spandex fibers (see Fibers, elastomeric) were introduced during this time. In addition, urethane-based synthetic leather (see Leather-LIKEmaterials) was introduced by Du Pont under the trade name Corfam in 1963. 

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