Fiber spinning procedure

Hollow fiber spinning dopes and preparation procedures vary over a wider range than their flat-sheet equivalents, but some representative dopes and spinning conditions taken from the patent literature [98,103,104] are given in Table 3.4. 

Is used in the textile industry as an antistat and lubricant for wool and synthetic fiber processing, and as a co-emulsifier and antistat in synthetic fiber spin finishes. It is also an anti-precipitant, leveling, and migrating agent in various dyeing procedures, and an antistat in carpet shampoos. 

High speed spinning procedures for the manufacture of high denier polypropylene fibers and yams require application of nucleating agerrls, such as dibenzylidene sorbitol, para-methyldibenzylidene sorbitol, bis-(3,4-dimethyl benzylidene) sorbitol, and sodium 2,2 -methylene-bis-(4,6-di-t-butylphenylene) phosphate. They are used in concentration of 2500-3000 ppm. ... 

Two different types of applications of antimicrobial finishing have been described. The classical procedure for applying the antimicrobial is still as an aftertreatment but the incorporation of the antimicrobial in the fiber spinning mass is becoming more and more popular. Besides all the positive aspects the consumer can benefit from, in the background there is the aspect of safety for man and the environment which certainly has to be paid attention to in the same manner. The given examples demonstrate some of the possibilities that really meet all requirements of a state-of-the-art antimicrobial treatment. 

The reverse of this procedure may be important in design situations that is, the entrance correction must be known as a function and included in the overall pressure drop calculations. In extruder dies and spinerettes for fiber spinning, L/R values rarely exceed 10, and the entrance loss may be the major contribution to the overall pressure drop. Carley provides examples of design calculations involving these concepts. 

The PEI substrate hollow fibers were prepared using the dry - wet spinning technique to form integrally skinned asymmetric hollow fiber membranes. Two different polymer solution compositions were utilized. In the first case a 22.5 wt% solution of PEI in dimethylacetamide (DMAc) or N-methylpyrrolidone (NMP), containing 1.0 - 1.5 wt% of lithium nitrate was used following the method similar to that described by Deng and others. In the second case a spinning procedure described by Kneifel and Peinemann was adopted. Here NMP was used as the solvent and y-butyrolactone (GBL) was used as the nonsolvent. 

One report (13) describes the procedure for spinning dry asymmetric ceUulose acetate fiber with a bore skin. Such fibers are spun in a modified dry-spinning process in which a volatile Uquid (methyl formate) is used as the ceUulose acetate solvent. The bore coagulating Uquid is isopropyl alcohol, which is subsequentiy removed. The advantages of these dry fibers over most ceUulose acetate membranes are that they can be stored dry, they are wet-dry reversible, they can be sterilized and packed dry, and they are ready for use without removal of preservatives. 

Early in the manufacture of PP, a concept was developed for dry spinning directly from the solution obtained in the polymerization operation. Had it been feasible, it would have been the realization of a chemical engineer s dream the gaseous olefin fed into one end of the equipment, and the packaged fiber, ready for shipment to a textile mill, coming out the other end. But it did not turn out that way, and today melt spinning is the accepted technique for the production of staple fibers, monofilament, and multifilament yams. To this usual method have been added the fibrillation and the slit film procedures for producing yams. 

Production. Recognition that the shish-kebab fibers produced by the surface-growth procedure result from the deformation of a gel-like entangled network layer at the rotor surface led to the development of gel-spun polyethylene fibers. The fiber is made by the solution spinning method. The polymer is... 

Researchers at du Pont (Dhingra, 1980) made a continuous a-alumina fiber by spinning a viscous solution. Du Pont Co. does not make these fibers any more. Nevertheless, we give a brief description of this process of making alumina fiber because it represents an important technique. The basic fabrication procedure involves three steps ... 

Numerous copolymer compositions have been screened with regard to ultimate carbon fiber properties, under comparable conditions of spinning, stabilization and carbonization. Although it is evident that different compositions will require different conditions for optimal properties, it was felt that a standard screening procedure, taking care of complete stabilization (match test), and providing for a minimum of fiber breaks, should help to select potential candidates. 

Around the same time, Mansmann and coworkers reported the production of carbon fibers from a variety of dry-spun materials, including lignin (lignosulfonates) by the simple addition of small amounts of PEO or acrylic acid-acrylamide copolymers. Although similar to the procedure of Ohtani, Mansmann employed acidic rather than neutral and/or alkaline spinning conditions. 

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