A study of fiber extrusion in wet spinning. II. Effects of spinning conditions on fiber formation

Han, Chang Dae; Segal, Leon

doi:10.1002/app.1970.070141206

Cited by 40 publications

(29 citation statements)

References 8 publications

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“…The draw down ratio is defined as the ratio of the tow velocities, exiting-to-entering the zone of interest. The spin draw (sampling point I), or draw applied during coagulation, calculated from the apparent entering and exiting velocities, was less than 1, which has been observed by others [12][13][14][15][16][17]. The tow velocity entering coagulation was calculated using the known, constant volumetric flow rate of the dope, and the dimension of the spinneret, and was used, uncorrected for viscoelastic die swell of the extruded jets, for the velocity calculation.…”

Section: IV Iii Iimentioning

confidence: 99%

Properties of PAN Fibers Solution Spun into a Chilled Coagulation Bath at High Solvent Compositions

Morris

Weisenberger

Rice

2015

Fibers

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Abstract:In this work, multifilament, continuous polyacrylonitrile (PAN) fiber tow was solution spun mimicking industrial processing at the small pilot scale (0.5 k tow), while carefully altering the composition of the coagulation bath, in order to determine the effect on the resulting fiber shape, density, orientation, and tensile properties at varying points in the spinning process. Novel here are the abnormally high coagulation bath solvent compositions investigated, which surpass those often reported in the literature. In addition, the coagulation bath was maintained at a slightly chilled temperature, contrary to reported methods to produce round fibers. Further, by altering the composition of the bath in a step-wise fashion during a single spinning run, variations in all other process parameters were minimized. We found that with increasing solvent composition in the coagulation bath, the fibers not only became round in cross section, but also became smaller in diameter, which persisted down the spin line. With this decrease in diameter, all else equal, came an accompanying increase in apparent fiber density via a reduction in microvoid content. In addition, molecular orientation and tensile properties also increased. Therefore, it was found that inadequate understanding of the coagulation bath effects, and spinning at low coagulation bath solvent compositions, can hinder the ability of the fiber to reach optimum properties.

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Section: IV Iii Iimentioning

confidence: 99%

Properties of PAN Fibers Solution Spun into a Chilled Coagulation Bath at High Solvent Compositions

Morris

Weisenberger

Rice

2015

Fibers

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“…Under this condition, the jet stretch only leads to slippage between the solid skin and fluid core but does not make the PAN chains extend effectively. [18] Thus, a higher orientation in coagulation seems to be obtained by employing a higher shear force combined with an appropriate jet stretch.…”

Section: Effect Of Jet Stretch On the Orientationmentioning

confidence: 99%

Effect of Jet Swell and Jet Stretch on the Structure of Wet-Spun Polyacrylonitrile Fiber

Ouyang

Chen

Zhang

et al. 2011

Journal of Macromolecular Science, Part B

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The jet swell effect in the wet spinning of polyacrylonitrile (PAN) fiber was studied by optical microscopy and the jet swell ratio was obtained through directly measuring the diameter of the freely extruded fibers. For reflecting the actual drawing situation of the fibers in the coagulation process, the jet stretches were then corrected from the apparent values to the true values, and their effect on the cross-sectional morphology, internal structure, and orientation of the wet-spun PAN fibers was studied by optical microscopy, scanning electron microscopy, and X-ray diffraction, respectively. The results showed that jet stretch plays an important role in eliminating the adverse effects caused by the jet swell effect and affects the fiber structure; PAN fibers of uniform denier, dense and homogenous structure, and high orientation can only be obtained at a suitable jet stretch.

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“…22 The theory and diffusion models related to this boundary movement were well surveyed. 23 When the spinning solution is extruded into the coagulation bath, the diffusion interchange occurs between the two phase, one is solvent as DMSO, the other is insolvent as water, a very distinct moving boundary turns out, one side of the boundary is hard, while the other side is the soft original gel. This boundary begins at the surface and moves inward to the center.…”

Section: Effect Of Coagulation Ratementioning

confidence: 99%

Effects of different coagulation conditions on polyacrylonitrile fibers wet spun in a system of dimethylsulphoxide and water

Wang

2007

J of Applied Polymer Sci

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Polyacrylonitrile (PAN) precursors were prepared by the wet spinning way. The effects of the coagulation conditions, such as coagulation temperature, coagulation ratio, and coagulation concentration, are discussed in detail. While keeping the coagulation bath concentration constant, as the coagulation bath temperature increased, the cross section deviated less from a circular form, and the as-spun fiber diameter decreased. Measurement to the rate of the boundary movement has been calculated depending on the coagulation rate. While keeping the coagulation bath temperature constant, high coagulation bath concentration can cause more coagulant to diffuse into the solution to the polymer precipitated consequently, which led to a faster coagulation rate. The as-spun fiber from high coagulation concentration was compacted than those from low concentration. The character of the formed structure reflected the system mobility and capability to crystallize. Improvement in fiber density in the as-spun fiber resulted in improvements in the tensile strength of the as-spun fiber.

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A study of fiber extrusion in wet spinning. II. Effects of spinning conditions on fiber formation

Cited by 40 publications

References 8 publications

Properties of PAN Fibers Solution Spun into a Chilled Coagulation Bath at High Solvent Compositions

Properties of PAN Fibers Solution Spun into a Chilled Coagulation Bath at High Solvent Compositions

Effect of Jet Swell and Jet Stretch on the Structure of Wet-Spun Polyacrylonitrile Fiber

Effects of different coagulation conditions on polyacrylonitrile fibers wet spun in a system of dimethylsulphoxide and water

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