Elastomeric fibres

Spandex fibres have dogbone to rounder cross-section and tend to be larger in 

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Elastomeric fibres based upon both polyester-urethane and polyether-urethane structures followed. The early work by Bayer led to the use of highly polar solvents such as dimethyl formamide. Formation of fibres by reactive spinning, where the isocyanate-ended polymer is extruded into an aqueous solution of a chain-coupling agent, was described in 1949 [75] and by dry-spinning a solution of the chain-coupled polymer in 1951 [76], However, Bayer did not immediately use their technology to produce commercial fibres [77],... 

Fabrics containing elastomeric fibres can be heat-set. A tricot or sleek-knit fabric knitted from nylon 6 and polyurethane may be satisfactorily heat-set at 180-185 C for 20-25 sec. Slightly higher temperatures (190 C) may be used for nylon 6,6. However, the required width and stretch characteristics of the finished fabric determine the precise conditions to be employed with a particular fabric [29]. 

Testing of the temperature dependence of the extension and shrinkage behaviour at low (TMA) or oscillating (DMA) yarn tension glass temperature, elasticity and other parameters for exact differentiation of elastomeric fibres. 

The prepolymer (1) above has two reactive end groups. Further polymerization can therefore be brought about by coupling with bifunctional reagents such as diamines, diols and also water. The reaction with a diamine gives the pol)rmer (2) which can be dissolved in dimethylforma-mide or dimethyl acetamide and then dry-spun to give elastomeric fibres. 

The most important area for PTHF and THF-alkylene oxides copolymers remains the PU elastomers area (including elastomeric fibres), the PTHF and the high THF content copolymers confer on the resulting PU elastomers specific properties, such as excellent hydrolytic stability, resiliency, low temperature stability, elasticity at lower temperatures, and resistance to fungus attack [7, 35, 36, 37]. 

Polyurethane fibres of a kind different to those described above have become important within the last decade these are elastomeric fibres, which are commonly called spandex fibres. These products are made either by solution spinning or by reaction spinning. In the first process, a hydroxy-terminated polyester (e.g., an adipate) or polyether (e.g., poly(oxytetramethylene) glycol) is treated with an excess of diisocyanate (e.g., tolylene diisocyanate) to give an isocyanate-terminated pre-polymer similar to those used for cast elastomers (Section 14.6.1). The pre-polymer is dissolved in a strongly polar solvent (e.g., dimethylformamide) and treated with an aliphatic diamine or hydrazine to effect chain extension with hydrazine the following reaction occurs ... 

Spandex fibres have replaced natural rubber elastomeric fibres in various... 

Spandex fibres have replaced natural rubber elastomeric fibres in various applications such as foundation garments on account of their greater strength, improved ageing characteristics and easier dyeability. They are also used in stretch fabrics. 

Apart from the two main categories of specialty fibres, a range of other specialty fibres has been developed. These include, for example, fibres for biomedical applications, water soluble poly(vinyl alcohol) fibres and elastomeric fibres based on segmented polyurethanes. " These fibres cannot be included here due to lack of space. 

Stankus, J.J., Guan, J., Fujimoto, K., and Wagner, W.R., 2006. Microintegrating smooth muscle cells into a biodegradable, elastomeric fibre matrix. Biomaterials, 27(5), pp. 735 4. 

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