Fibers production

In 1965, Harwell, at the request of RAE, initiated the production of 35 cm long staple carbon fiber in batches of about 4.5 kg, specifically for use at RAE. Once the commercial UK companies came on stream, Harwell turned their attention to making continuous fiber, at first some 300 m long [77]. The initial production was by a semi-batch process, where the precursor was wound onto metal frames for oxidation and then off-wound and coiled into a vertical pot furnace for subsequent carbonization. A problem associated with this procedure was that the lengths of fiber had in-built kinks, which were points of incipient weakness, where the precursor had come into contact with the metal frame during oxidation. 

Brand name Manufacturer filaments k filament Copolymers shape 

DralonT Bayer (Germany) 160 3.3 None (homopolymer) Dog-bone 

The gas evolution processes that occurred during the formation of carbon fibers up to 1000°C were studied by Bromley [85] and in the region 400-500°C, the main products evolved were NH3, CO2, H2O and CH4 together with high molecular weight hydrocarbons, but little 

Precursor Flexural strength Gpa Flexural modulus Gpa Strain to failure for 1100°C material % 

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Table 2. Worldwide Synthetic Fiber Production by Fiber, 10 t...

Crimp. The tow is usually relaxed at this point. Relaxation is essential because it gready reduces the tendency for fibrillation and increases the dimensional stabiUty of the fiber. Relaxation also increases fiber elongation and improves dye diffusion rates. This relaxation can be done in-line on Superba equipment or in batches in an autoclave. Generally saturated steam is used because the moisture reduces the process temperatures required. Fiber shrinkage during relaxation ranges from 10 to 40% depending on the temperature used, the polymer composition used for the fiber, and the amount of prior orientation and relaxation. The amount of relaxation is also tailored to the intended apphcation of the fiber product. 

Textile Fibers Products Identification A.ct, US. Public Eaw 85—897 U.S. Federal Trade Commission, Washington, D.C., effective Mar. 3,1960. 

Texturing. The final step in olefin fiber production is texturing the method depends primarily on the appHcation. For carpet and upholstery, the fiber is usually bulked, a procedure in which fiber is deformed by hot air or steam jet turbulence in a no22le and deposited on a moving screen to cool. The fiber takes on a three-dimensional crimp that aids in developing bulk and coverage in the final fabric. Stuffer box crimping, a process in which heated tow is overfed into a restricted oudet box, imparts a two-dimensional sawtooth crimp commonly found in olefin staple used in carded nonwovens and upholstery yams. 

The tendency of the strong, highly crystalline fibers to fibnUate, ie, to develop a hairy surface on wet-abrasion has, for the textile appUcations, been minimized by process changes both in fiber production and fabric manufacture. However, for nonwoven or speciaUty paper appUcations, this property can aUow potential users to develop ceUulosic microfibers during processing. 

Worldwide demand for DMF in acryhc fiber production has held up better than in the United States. The high solubiUty of polyacrylonitrile in DMF, coupled with DMF s high water miscibility, makes it an attractive solvent for this appHcation. Its principal competition in this area comes from DMAC. 

Glass fibers <3 fim are to be avoided because these are classed as respirable fibers which can enter and damage lung passages. Most glass fiber products have sufficient fiber lengths to prevent lung entry even if their diameters are <3 fim. 

Eig. 11. Composite hoUow-fiber production scheme (PEI = polyethyleneimine TDI = toluene 2,4-diisocyanate). Anisotropic (porous skin) polysulfone hoUow fiber is roUed into bath A and is lifted vertically (to avoid droplet formation) into a beating tube. The fiber is then passed through bath B and is... 

Worldwide synthetic fiber production for 1990 was 17.5 x 10 t (see Fibers survey). 

Fibrex Nickel Fibers, Product Brochure, National Standard Co., Mishawaka, Ind., 1987. 

A significant percentage of U.S. staple fiber production is packaged ia bales of extmsion coated spunbonded fabrics, so treated to render the fabric impervious. Synthetic fibers have been shipped worldwide ia this manner with great success. 

When selecting a particular paster adhesive, coating material, and coating process for sohd fiber packaging, the fact that sohd fiberboard lacks the open-flute stmcture (to facihtate exit of moisture from internal phes of paperboard) should be considered. It is generally desirable to minimize the amount of process water added with the adhesive or coating with sohd fiber products. Moisture trapped in the filler phes can result in pin holes or bhsters in the coating and/or warp of the sheet (15). 

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