Spinning and Fiber Properties

UHMW-PE/Decalin Dispersion under mixing condition 

Work by Prevorsek shows that the modulus of HMWPE is strain dependent in that with high impact it actually increases in modulus. At standard deformation rates Spectra 900 and 1000 are 120 and 170 GPa but at ballistic rates it can reach up to 300 GPa [188] (Tables 9.8 and 9.9). At these ballistic rates the material absorbing the energy of a projectile is proportional to the modulus of the material, thus making this material popular for the end use of bullet protection apparel [189]. 

Weight/unit length (den) (decitex) Ultimate tensile strength 900 1000 2000  

Smith and Lemstra [186] studied the effect of molecular weight on the tensile strength of melt and solution spun, ultra drawn PE fibers. They showed that the tensile strength (s) and tensile modulus (E) of drawn fibers increases with molecular weight (Mw) based on an empirical relationship [186]  

They [186] also found that decreasing polydispersity (Mw/Mn) enhances the tensile strength at specific molecular weight and tensile modulus. 

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While all available types of cellulose can be used, dissolving pulps are preferred for best spinning and fiber properties. The solvent preparation involves mixing orthophosphoric acid with polyphosphoric acid, in a 80 20 ratio at around 50° C and then cooling and storing for several hours to arrive at the desired concentration of anhydride. 

Fiber Spinning and Mechanical Properties Aside from providing the critical concentrations at which liquid-crystalline behavior appears. Table m also lists the processing concentrations of the candidate block copolymers. Since rigid molecules would aggregate together to form anisotropic domains as their concentration exceeds Cer the processing of molecular composites must be controlled within this limit. 

Flammability of PP becomes particularly critical in fibers, where solid additives may interfere with spinning and mechanical properties. A wide variety of flame retardants are therefore explored for such applications [35], often as coatings rather than additives. For example, addition of a liquid containing 45% Br+ 15% Cl, to polyvinyl acetate or acrylic latex, produces a flame retardant backing for PP fabrics, for applications such as upholstery [18]. 

Table 8.49 is a smnmary of spinning process conditions for producing single filaments of PEA resins. The fiber was spun into ambient air under the above conditions. The properties of the fibers have been summarized in Table 8.50. Tables 8.51 and 8.52 present spinning process conditions and fiber properties for FEP resins. Figure 8.40 compares fiber tenacity vs melting point of the fiber for Heffher, et al. s, and Vita sf " ] works.

VassUatos, G., Knox, B.H., Frankfort, H.R.E. Dynamics, structure and fiber properties in high-speed spinning of polyethylene terephthalate. In High-Speed Fiber Spinning. Science and Engineering Aspects, Ziabicki, A., Kawai, H., eds. John Wiley Sons, New York, 1985, pp. 383-429. 

Shilton, S.J., G. Bell and J. Ferguson, The Rheology of Fiber Spinning and the Properties of Hollow-Fiber Membranes for Gas Separation , Polymer, 35 (24) (1994). 

Fig. 11. Effect of spinning speed on properties of nylon-6 fibers, where (T) is the tangent modulus (° ), the tenacity and (A ), the elongation. To convert...

Flame retardants designated for nylon include halogenated organic compounds, phosphorous derivatives, and melamine cyanurate (160—163). Generally, flame retardants are difficult to spin in nylon because of the high loading required for effectiveness and their adverse effects on melt viscosity and fiber physical properties. 

Currently, HVI systems are providing rehable information on six characteristics of quaUty from a cotton sample in approximately 30 s that are highly related to the spinning quaUty and market value of the cotton. As of the 1991 crop year, cotton must be tested by HVI to be eligible for price supports in the United States. Information on every bale of cotton should gready improve the marketing of cotton and encourage the production of cotton with fiber properties desired by users. 

As the basic fiber microstructure is determined during the spinning and drawing processes, several spinning process variables have a significant impact on fiber properties e.g., flow rate, winder speed, spinnerette geometry, etc.). Spinning... 

Sulfolane is a water-soluble biodegradable and highly polar compound valued for its solvent properties. Approximately 20 million pounds of sulfolane are consumed annually in applications that include delignification of wood, polymerization and fiber spinning, and electroplating bathes.It is a solvent for selectively extracting aromatics from reformates and coke oven products. 

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