Spinning bicomponent

There are variations of the spinning process that have not been mentioned here, e.g., bicomponent spinning. Usually, this operation is carried out by employing two extrusion systems that keep the resins separate until just before the streams exit the spinneret. Sheath-core or side-by-side yarns can be spun by this process. Simpler bicomponent yarns are spun with mixed incompatible resins from mixed-pellet blends. 

In bicomponent spinning, two strongly bonded (but separable) polymers of different chemical and/or physical structure are processed into single filaments by means of special spinnerets, e.g. side-by-side type (S/S), core-cover type (C/C) or matrix/fibril type (M/F) (see Fig. 2.2). Bicomponent spinning offers the best opportunities for the production and development of micro- and nanofibres by the use of matrix/fibril... 

Keywords Biotextile Fibers and filaments Melt spinning Bicomponent spinning Textile structures Braids Knits Nonwovens Spacer fabric... 

Another approach is to make ultra-fine (submicron diameter) filaments by the island-in-the-sea technique, where the sacrificial matrix (sea) polymer is removed in a subsequent post-spinning process. Thus, by using bicomponent spinning technology, the material strength profile, resorption profile, and the biological properties can be engineered into the fiber to meet specific medical requirements. 

Bacillus megaterium, 29 Bacterial polyesters, 29 Bicomponent spinning, 18 Bioabsorption, 2 Biocompatibility, 2 Biodegradation, 2 Bioerosion, 2 Biofunctionality, 3 Biological hydrolysis, 60 Biological oxidation, 60 Biomaterial, 2 Biopol, 30 Bioresorption, 2 Biotextile, 11 Bombyx mori, 55 Bulk erosion, 8... 

Polyacrylonitrile (PAN) is produced by the additional polymerization of acrylonitrile always, the second and the third monomers are used for the modihcation of dyeability and spinnability. They can then be spun into fibers by dry or wet spinning methods, such as how Orion with a distinctive dumbbell cross section is spun by dry process produced by DuPont, and Acrilan had circular cross section and is spun by the wet extrusion technique produced by Monsanto. PAN fiber can also get the crimp structure like wool by using the bicomponent spinning process in fiber preparation. Properties of PAN fibers are listed in Table 2.27. 

Islands in the sea fibres were first introduced by Toray in the 1970s and are a relatively fast method to produce nanofibre fabrics. The process involves bicomponent spinning and extruding two polymer componaits from one spinning die, whereby the nanofila-ments are supported in the surrounding polymer matrix, as shown in Fig. 4.4. 

W. E. Fitzgerald and J. P. Knudsen (June 1967), Mixed-stream spinning of bicomponent fibers. Textile Res. /., 37(6), 447-453, Conventional Bicomponent Spinning. 

J. Radhakrishnan, H. Ito,T. Kikutani and N. Okui (January 1999), Enhancement of fiber structure formation of a hquid crystalline copolyester via ultra-high speed bicomponent spinning with poly (ethylene terephthalate), Polym. Eng. Sci,39(1), 89-98. 

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,...

Bicomponent technology has been used to introduce functional and novelty effects other than stretch to nylon fibers. For instance, antistatic yams are made by spinning a conductive carbon-black polymer dispersion as a core with a sheath of nylon (188) and as a side-by-side configuration (189). At 0.1—1.0% implants, these conductive filaments give durable static resistance to nylon carpets without interfering with dye coloration. Conductive materials such as carbon black or metals as a sheath around a core of nylon interfere with color, especially light shades. 

In another approach, filaments containing two polymers that do not adhere to each other are spun and then split. One may, for example, spin a bicomponent fiber of nylon that has several filaments of polyester embedded. After a fabric containing bicomponent filaments has been woven, it is treated to split the components, thus converting the original filament to several smaller filaments. Deniers of the order of 0.1 can be achieved by this ingenious method. In the last method, instead of... 

Polylactic acid also has many potential uses in fibres and non-wovens. It is easily converted into a variety of fibre forms using conventional melt-spinning processes. Spunbound and meltblown non-wovens as well as monocomponent, bicomponent, continuous (flat and textured) and stable fibres are all easily produced. 

Bicomponent fibers A fiber made by spinning two compositions concurrently in each capillary of the spinneret. 

Bicomponent fibres are sjmthetic fibres composed of two firmly but separately combined polymers of different chemical and physical structures. The structure of the bieomponent depends on the shape of the spinnerette orifice (side-by-side, sheath eore, matrix - fibril and multi-fibrillary) and the type of spinning method. Due to the structural differences, the two components shrink differently on heat treatment and form crimp and greater bulk in the fibre. The first fully synthetic bicomponent was an acrylic (Sayelle, Orion 21). The use of sheath-core fibres composed of nylon 6,6 and nylon 6 (Heterofil, ICI) for floor coverings is described. 

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