Fabrics polyurethane fibers

Polyurethanes are used for the fabrication of fibers, while crosslinked polyurethanes are employed as lacquers and adhesives, as coatings for textiles and paper, and as elastomers and foams. 

The more flexible blocks are derived from low-molecular-weight (MW 1,000 to 4,000) polyesters or polyethers with —OH groups at each end of their chains. Polyurethane fibers are fairly soft and elastic and have found use as spandex and Lycra , the stretch fabrics used in bathing suits, leotards, and undergarments. 

Amoroso NJ, D Amore A, Hong Y, Wagner WR, Sacks MS. Elastomeric electrospun polyurethane scaffolds the interrelationship between fabrication conditions, fiber topology, and mechanical properties. Adv Mater 2011 23 106-11. 

Commercially available polypyrrole-coated products from Achilles are predominantly available as coated films, but a number of products based on nonwoven textiles and used as static dissipating bars, brushes, and rollers for photocopying and fax machines are also being offered (see Fig. 35.10). A similar nonwoven material is used in filtration equipment. They also are offering conductive gloves for applications in clean rooms based on a nonwoven fabric constructed of coated polyurethane fibers. 

High molai mass polyuiethanes weie obtained from condensation of 4,4 -(hexa luoioisopiopylidene)bis(phenylchloiofomiate) with various diamines (125). These polymers could be cast into transparent, flexible, colodess films or spun into fibers which showed promise as crease-resistant fabrics. Other polyurethanes discovered are good candidates for naval and aerospace apphcations (126). 

Man-Made Leathers. These materials contain a nonwoven fabric which is impregnated with a polyurethane to improve fiexibiHty, processibiHty, and conformabiHty (Fig. 9). Advanced man-made leathers contain microfibers as fine as 0.03 tex (0.3 den) or less to imitate coUagen fiber bundles, thereby attaining the soft feel and appearance essential for soft leather use. Polyurethane in the substrate is usually provided with porous stmcture by poromeric technology. The coating layer is also porous in the two-layer type man-made leathers (5—10). 

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). 

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. 

Dry A filter manufactured from cotton wool, glass-fiber fabric, pleated paper, foamed polyurethane, cellular polythene, or other suitable materials. As the name suggests, the filter is dry in nature and has no oil coating. 

SCRIMP process This Seeman Composites Resin Infusion Process (SCRIMP) is described as a gas-assist resin transfer molding process. As an example glass fiber fabrics/ thermoset vinyl ester polyester plastic and polyurethane foam panels (for insulation) are placed in a segmented tool. A vacuum is pulled with a bag so that a huge amount of plastic can be drawn into the mold (Marco process approach). Its curved roof is made separately and bonded to the box with mechanical and adhesive fastening. It is similar to various reinforced plastics molding processes. 

Another widespread use of polyurethane elastic fibers is in disposable diapers and adult incontinence garments. Elastic strands are incorporated into waistbands and side panels made of non-woven fabrics where they improve fit and reduce leakage. 

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. 

Blood circulates inside the fibers and dialysate outside (Figure 18.5). The fibers are imbedded at each end in polyurethane that ensures separation between blood and dialysate. During fabrication, the bundle ends must be carefully cut with a blade to reopen each fiber. Blood inlet and outlet are located in caps screwed on the housing, which are designed to distribute blood uniformly into all fibers, while dialysate ports are located at each end of the housing, perpendicular to the fibers. 

Cyclic oligomeric phosphonates with the varying degrees of structural complexity (Structure 5.4) are also available in the market.25 They are widely used as flame-retardant finishes for polyester fabrics. After the phosphonate is applied from an aqueous solution, the fabric is heated to swell and soften the fibers, thus allowing the phosphonate to be absorbed and strongly held. It is also a useful retardant in polyester resins, polyurethanes, polycarbonates, polyamide-6, and in textile back coatings. A bicyclic pentaerythritol phosphate has been more recently introduced into the market for use in thermosets as well as for polyolefins (preferably, in combination with melamine or ammonium polyphosphate)... 

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