Fiber drawn

It is more convenient to use the procedure of the first kind for higher drawn fibers (over 350% of elongation) and the second procedure for fibers of smaller drawing. The value of the angle of inclination of the texture depends on the magnitude of the drawing applied. As a result of the investigations of one of the authors... 

We have found that high molecular weight poly (p-PIN)s readily yields fibers by manual drawing from the melt. X-ray analysis of melt-drawn fibers showed a characteristic amorphous halo with a d spacing at 6.2 A. 

Die-drawing 143 Die-drawn fibers 144 Differential polarizability tensor 91 Differential scanning calorimetry 63, 165 Diffusion 189... 

A report130 of DSC measurements on polybenzimidazole fibers describes important differences for the glass transition temperature depending on die mechanical treatment of the fiber. An as-spun fiber exhibits a Tg at 387°C instead of 401°C for a drawn fiber free to shrink or 435°C for a drawn fiber widi fixed length. 

There are several interesting applications reported in the literature, such as insulated wire and cable, UV cross-linking of drawn fibers, and tapes from ultra-high-molecular-weight polyethylene. Semi-interpenetrating networks (IPNs) from acrylates and polyurethanes are suitable as UV curable adhesives with high elasticity, good impact resistance, and excellent adhesion to a variety of substrates. ... 

Mechanical properties of the blends were investigated in fiber form. The as-spun fiber tensile properties are summarized as shown in Table 4. These fibers were further drawn at elevated temperatures at various draw ratios. These drawn fibers were stronger than the as-spun fibers. Table 5 illustrates the effects of temperature and draw-ratio on the fiber properties. Drawing at 400 °C at a ratio... 

The recent studies of the phase structure of linear polyethylene by refined NMR analyses are reviewed. The phase structure of the polymer in various crystalline forms, including bulk-crystals, solution-crystals and drawn fibers, is discussed in terms of different modes of molecular mobilities in a wide range of temperature. 

In the fiber structure, molecular chains in the crystalline region are highly oriented parallel to the fiber axis and a majority of molecular chains in the noncrystalline region are also highly oriented, so that both the conformational versatility and the mobility of molecular chains are much limited. But even in highly drawn fibers a significant, albeit minor, amount of amorphous material with a liquidlike mobility still exists. 

White (1955) believes that differential thermal analysis curves obtained by him on heating drawn fibers of 6, 6-6 and 6-10 nylons as well as polyethylene terephthalate, indicate that at first crystallites disorient and then melt. He found two peaks in what would correspond to a specific heat-temperature curve. However, it is difficult to understand why the disorientation of oriented crystals would involve the absorption of energy. 

Marx, Smith, Worthington and Dole (1955) observed a sudden change of slope of the cv— T curve of drawn 6-Nylon at 115° C. Although this break in the value of dcjd T was reproducible (observed during three different experiments), it disappeared on annealing the drawn fibers just below the melting point. 

Nuclear magnetic resonance provides a valuable complement to internal friction in studies of molecular motion on polytetrafluoro-ethylene. Pertinent studies have been reported by Smith, Slichter, Wilson and Pake, Powles and Kail, and by Sinnott. Hyndman and Origlio studied the NMR spectra of drawn fibers. They found that the... 

Figure 8 SEM pictures showing the morphology of artificial fibroin fibers from different processings, (a) Drawn fibers from TFA dope solution (Ha et al., 2005). (b) Cross-section and surface (inset) of fiber after post-drawn from aqueous solution (Lin et al., 2007).

Fischer, E. W. Thermodynamical explanation of large periods in high polymer crystals and drawn fibers. Ann. N. Y. Acad. Sci. 89, 620—634 (1961). 

Fibers could be drawn from concentrated syrups of these products in toluene. The drawn fibers could not directly be converted to ceramic fibers, because they melted on being heated, and a cure step was required to render them infusible. The required cure could be accomplished by UV irradiation of the fibers. Following this treatment, pyrolysis of the fibers in a stream of argon gave black ceramic fibers, and pyrolysis in a stream of ammonia gave white ceramic fibers. 

Studies of craze microstructure and the surrounding displacements of crazes have established that the only parts around a craze that undergo plastic deformation are concentrated into a process zone at the tip of the craze, and into a fringing layer all around the entire craze body. In the process zone craze matter is generated by one of the two processes discussed above, and fibrils are necked down to the final extension ratio. In the fringing layer, additions are made to craze fibrils by drawing polymer out of half space. Outside the idetifiable parts of a craze, the solid polymer remains entirely elastic while inside the craze body the fully drawn fibers carry the required craze tractions purely elastically in their orientation hardened state at the... 

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