Fiber-Spinning Processes

These solvents include tetrahydrofuran (THF), 1,4-dioxane, chloroform, dichioromethane, and chloroben2ene. The relatively broad solubiHty characteristics of PSF have been key in the development of solution-based hoUow-fiber spinning processes in the manufacture of polysulfone asymmetric membranes (see Hollow-fibermembranes). The solvent Hst for PES and PPSF is short because of the propensity of these polymers to undergo solvent-induced crysta11i2ation in many solvents. When the PES stmcture contains a small proportion of a second bisphenol comonomer, as in the case of RADEL A (Amoco Corp.) polyethersulfone, solution stabiHtyis much improved over that of PES homopolymer. 

Polymer Solvent. Sulfolane is a solvent for a variety of polymers, including polyacrylonitrile (PAN), poly(vinyhdene cyanide), poly(vinyl chloride) (PVC), poly(vinyl fluoride), and polysulfones (124—129). Sulfolane solutions of PAN, poly(vinyhdene cyanide), and PVC have been patented for fiber-spinning processes, in which the relatively low solution viscosity, good thermal stabiUty, and comparatively low solvent toxicity of sulfolane are advantageous. Powdered perfluorocarbon copolymers bearing sulfo or carboxy groups have been prepared by precipitation from sulfolane solution with toluene at temperatures below 300°C. Particle sizes of 0.5—100 p.m result. 

Hollow-fiber permeators, 26 22 Hollow fibers, 13 389-390 cellulose ester, 26 19 cellulosic, 26 18-20 ion-exchange, 26 15 mechanical considerations and dimensions for, 26 5-7 natural polymer, 26 23 polyacrylonitrile, 26 23 polyamide, 26 21-22 post-treatment of, 26 13-14 preparation of, 26 3 production of, 19 757 with sorbent walls, 26 26 technology of, 26 27 wet spinning of, 25 816, 817-818 Hollow-fiber spinning processes, 26 7-12 Hollow fiber spinning technology,... 

Rotary drum vacuum filters, 11 345, 355-357. See also Drum filters Rotary dryers, 9 121-122 indirect-heat, 9 129 steam-tube, 9 129-130 Rotary fiber spinning process, 13 387 Rotary furnace technologies, 21 391 Rotary hearth furnaces, 13 177—178 Rotary impeller vane meters,... 

Improved Comfort Properties. Wear comfort generally means cotton-like properties, The ability lo absorb moisture from the skin and ihe softness of cotton fabrics are considered to be the two key properties for comfort. The extremely line denier of cotton fibers accounts for its softness. Both properties can be achieved in acrylic fibers. Improved moisture retention can be achieved by incorporating hydrophilic comonomers that decrease ultimate fiher density, by modifying the fiber spinning process, ur by using after-treatments such as modified finishes. 

Figure 2.35 Schematic diagram of a fiber spinning process.

Figure 3.52 The fiber spinning process with detail of a stretching fiber during the cooling process.

Figure 6.18 Schematic diagram of the fiber spinning process in the post-extrusion die region.

Fig. 14.1 (a) Schematic representation of the melt fiber spinning process, (b) Photograph of a... 

The mathematical formulation of the fiber-spinning process is meant to simulate and predict the hydrodynamics of the process and the relationship between spinning conditions and fiber structure. It involves rapid extensional deformation, heat transfer to the surrounding quenching environment, air drag on the filament surface, crystallization under rapid axial-orientation, and nonisothermal conditions. 

Fig. 14.11 Schematic representation of fiber spinning process simulation scheme showing the multiple scale simulation analysis down to the molecular level. This is the goal of the Clemson University-MIT NSF Engineering Research Center for Advanced Engineering Fibers and Films (CAEFF) collaboration. CAEFF researchers are addressing fiber and film forming and structuring by creating a multiscale model that can be used to predict optimal combinations of materials and manufacturing conditions, for these and other processes.

Figure 2.2 Schematic of a generic fiber spinning process.

The following process variables are very important in any fiber spinning process ... 

In all cases, because of the orientation phenomenon inherent to the fiber spinning process, the phases are all aligned in the longitudinal direction. In the fibril-matrix structure, the number and size of fibrils depend on composition, rheological properties of the constiments and the type of deformation during spinning. A tree-ring structure , as shown... 

FIGURE 5.66 Schematic diagram of a hollow-fiber spinning process. (After Chung, T. S. and Hu, X. 1997. /. Appl. Polym. Sci.y 66, 1067. With permission. )... 

The wet and dry fiber-spinning processes with emphasis on the fiber formation mechanism... 

H. Yasuda et al.. Gel spinning processes, in Advanced Fiber Spinning Processes, P.T. Nakajima, Ed., Woodhead Publishing Limited, Cambridge, p. 174 (1994). 

A. Ziabicki, The Role of Phase and Structural Transitions in Fiber Spinning Processes, presented at Society of Fiber Science and Technology, Japan, 25th Anniversary, Tokyo-Osaka (1969). 

Recent researches in life cycle assessments (LCA) have also focused to enable PLA to find its place among traditional commodity polymers for many applications in the agricultural sector as well as in the packaging field (the food and nonfood sector). It was found that PLA can be processed like all other thermoplastic polymers with extrusion, injection molding, blow molding, thermoforming or fiber spinning processes into various products. 

Fiber spinning process Melting spinning is the common process used to make textile-type polyolefin fibers (UHMWPE is an exception due to its ultra-high molecular weight as will be seen later). The process of making continuous filament yam consists of the following steps [2] ... 

G.G. Lipscomb, The melt hollow fiber spinning process steady-state behavior, sensitivity and stability, Polym. Adv. Tech., 5 (1994) 745-758. 

Manufacture of gas-separation membrane modules is largely a machine-assisted, labor-intensive operation. Polymer dopes are typically prepared batchwise with sufficient hold time to insure uniformity. The membrane performance is largely controlled by the polymer precipitation step and very dependent upon phase behavior and precipitation kinetics. Thus, it is essential that processing conditions be maintained as uniformly and as constant as possible if product quality and uniformity is to be preserved. For this reason, membrane-fihn formation and hollow-fiber spinning processes are usually operated continuously or for extended run times. Since the intermediate film or fiber must eventually be converted into discrete items, the continuous process is typically interrupted by collection of the membrane formed on spools or fiber skeins where it may be inventoried briefly before batch processing into the final assembly resumes. 

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