Biconstituent fibers

Fiber biconstituent A hybrid or composite fiber comprising a dispersion of fibrils of one synthetic plastic within and parallel to the longitudinal axis of another also a construction of plastic and metal or alloy filaments. 

Other elastomeric-type fibers iaclude the biconstituents, which usually combine a polyamide or polyester with a segmented polyurethane-based fiber. These two constituents ate melt-extmded simultaneously through the same spinneret hole and may be arranged either side by side or ia an eccentric sheath—cote configuration. As these fibers ate drawn, a differential shrinkage of the two components develops to produce a hehcal fiber configuration with elastic properties. An appHed tensile force pulls out the helix and is resisted by the elastomeric component. Kanebo Ltd. has iatroduced a nylon—spandex sheath—cote biconstituent fiber for hosiery with the trade name Sidetia (6). 

Fig. 1. Stress—strain curves A, hard fiber, eg, nylon B, biconstituent nylon—spandex fiber C, mechanical stretch nylon D, spandex fiber E, extruded latex...

More recentiy, melt-spun biconstituent sheath—core elastic fibers have been commercialized. They normally consist of a hard fiber sheath (polyamide or polyester) along with a segmented polyurethane core polymer (11,12). Kanebo Ltd. in Japan currentiy produces a biconstituent fiber for hosiery end uses called Sideria. 

Nylon—spandex sheath—core biconstituent fiber. 

Fig. 2. Ultrafine fibers are produced by spinning bicomponent or biconstituent polymer mixtures, highly stretching such products to ultrafine deniers, and extracting or otherwise removing the undesked matrix carrier to release the desked ultrafine fibers (30). For example, spinning polyester islands in a matrix of polystyrene and then, after stretching, dissolving the polystyrene to leave the polyester fibers cospinning polyester with polyamides, then stretching,...

M.W. Olson G.H- Brice, Bicomponent and Biconstituent Fibers in Ballistic Fabric for Personnel Armor , Rept No USA-NLabs, C/-PLSEL-TR-71-48CE, TS-173, Contract DAA17-70-C-0032, Uniroyal Inc, Wayne (1971)... 

Blends of two fiber-forming polymers can be used to spin several types of two-component fibers (Allied Chemical Corp., n.d. Buckley and Phillips, 1969 Cresentini, 1971 Fukuma, 1971 Hayes, 1969 Mumford and Nevin, 1967 Papero et ai, 1967 Pollack, 1971). As shown in Figure 9.3, the two components may be arranged as mated half-cylinders, in a skin-core configuration, or in a matrix-fibril configuration. The first two configurations are referred to as bicomponent, the last as biconstituent fibers. 

Figure 9.3. Classification of bicomponent and biconstituent fibers. (Allied Chemical Corp., advertising literature) (A) Bicomponent system (B) skin-core system (C) matrix-fibril system.

Figure 9.5. Micrograph of a drawn biconstituent fiber containing 30 % poly(ethylene terephtha-late) and 70 % nylon 6. The fibers form elongated, tapered cylinders about 100-200 //m in length. (Buckley and Phillips, 1969.)...

A second important type of biconstituent fiber is a semicompatible blend on nylon 66 with nylon 61 (I referring to isophthalic acid), with nylon 61... 

Biconstituent fiber n. A fiber extruded from a homogeneous mixture of two different polymers. Such fibers combine the characteristics of the two polymers into a single fiber. 

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