Fibers: elastomeric

Since the elastomeric fibers are often a component in the core of blended yarns, coloration is not important in all applications. Rubber fibers cannot be dyed readily and are colored through mixing of pigments into the rubber prior to extrusion into fibers. Spandex fibers are more 

---

Elastomeric Fiber. Elastomeric fibers are prepared by the polymerization of polymeric polyols with diisocyanates. 

The structure of elastomeric fibers is similar to that illustrated for polyurethane foams. 

Elastomeric adhesives Elastomeric copolymei Elastomeric fibers Elastomeric polyamide... 

Nonspandex elastomeric fibers based on segmented polyesters and polyesters ate currendy being developed that can be melt-spun iato threads (7). Teijia Ltd. produces an elastomeric fiber of this type with the trade name Rexe. 

The physical characteristics of current commercial mbber and spandex fibers are summarized ia Table 1. Typical stress—straia curves for elastomeric fibers, hard fibers, and hard fibers with mechanical stretch properties ate compared ia Eigute 1. 

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). 

Commercially, elastomeric fibers are almost always used in combination with hard fibers such as nylon, polyester, or cotton. Use levels vary from a low of about 3% in some filling stretch cotton fabrics to a high of about 40% in some warp-knit tricot fabrics. Raschel fabrics used in foundation garments normally contain 10—20% spandex fiber. 

For end uses demanding high dye lightfastness such as automotive iaterior fabrics, select premetallized dyes and uv inhibitors are appHed through the dye bath (179—182). Nylon can also be codyed with polyurethane elastomeric fibers, wool, acryflcs, polyesters, and ceUulosics (183). 

Block copolymers have become commercially valuable commodities because of their unique stmcture—property relationships. They are best described in terms of their appHcations such as thermoplastic elastomers (TPE), elastomeric fibers, toughened thermoplastic resins, compatibilizers, surfactants, and adhesives (see Elastot rs, synthetic—thermoplastic). 

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. 

When bleaching is requited, a reductive bleach with sodium hydrosulfite and sodium metabisulfite is used. Cotton blends may requite a hydrogen peroxide bleach at pH 9.0—9.5 prior to or iastead of the normal reductive bleach. Chlorine-type bleaches which damage elastomeric fibers are avoided. 

Elastomers come next in order of quantity sold worldwide. Like the previous categories, elastomers cover an extremely broad range of material types and application areas. They include cast elastomers, spray and rotational casting elastomers, thermoplastic elastomers, microcellular elastomers, gels, and elastomeric fibers. Each type is covered separately.13d> 14... 

Polyurethane elastomeric fibers, 205 Polyurethane elastomers, 201 Polyurethane foams, 20, 29, 202 preparation of, 251-252 Polyurethane formulations, one- and two-component system, 238-241... 

Elastic recovery, 19 744 in olefin fibers, 11 227—228 Elastic scattering, 24 88-89 Elastic springs, in virtual two-way SMA devices, 22 346-347 Elastic waves, 17 422 Elastohydrodynamic (EHD) lubrication regime, 15 211-212 Elastomer-coated dies, in bar soap manufacture, 22 752 Elastomer designations, ASTM, 9 552t Elastomeric fibers, dyeing, 9 204 Elastomeric polycarboranylsiloxanes,... 

Ultee, A. J., History of Spandex Elastomeric Fibers. In Manmade Fibers Their Origin and Development, Seymour, R. B. and Porter, R. S. (Eds), Elsevier Applied Science, Amsterdam, 1992, pp. 278-294. 

Property of polymer e, elastomeric /, fiber- or film-forming p, powdery. 

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 fibers are used in cul rubber and extruded latex and spandex fibers. 

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. 

The development of elastomeric fibers has resulted in a variant of wet spinning called reaction or chemical spinning. In point of fact, rayon, the first wet-spun material, might properly be said to be produced by reaction wet spinning or chemical wet spinning because complex chemical reactions always have been involved in that operation. In any case, it has been found that the prepolymer of an elastomeric fiber may be extruded into a bath containing a highly reactive diamine so that the chemical conversion from liquid to solid occurs there. 

Types 1 and 4 tensile failures, which are of less interest to conservationists at this time, are caused by brittle crack propagation and by long axial splits, respectively. Such fractures can occur in ceramic and elastomeric fibers (both Type 1) and highly oriented aramids (Type 4). 

---