Answer:

The process creates orientation of macromolecules and as a result increases the strength of material. Fiber spinning is a typical example. It has the following peculiarities: deformation (flow and elastic strains) is primarily extensional and shear stresses are neglected.

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In this study, the effect of spinneret geometry, including the entrance angle α of the entrance channel, the length Ls, and the diameter D0 of the exit channel, on the spinning dynamics of dry-jet wet-spinning of cellulose/1-butyl-3-methylimidazolium chloride ([BMIM]Cl) solution was simulated by using finite element method. Based on the mathematical model of dry-jet wet-spinning established in our previous work (Xia et al., Cellulose 2015, 22, 1963) the radial and axial profiles of velocity, pressure, and shear rate in the spinneret and the profiles of diameter, temperature, and tensile stress in the air-gap region were obtained. From the simulated profiles, the effect of spinneret geometric parameters on the flow behavior and the pressure drop of polymer solution in the spinneret and the die-swell ratio near the spinneret was discussed. The entrance angle α of the entrance channel mainly influences the flow behavior of polymer solution in the spinneret and the die-swell effect near the spinneret. As the decrease of the entrance angle α of the entrance channel, the vortices in the spinneret could be removed and the die-swell ratio decreases. The increase of the length Ls of the exit channel results in the increase of pressure drop in the spinneret and the decrease of the die-swell ratio. It is also found that the increase of the diameter D0 of the exit channel reduces the flow velocity of polymer solution and decreases the pressure drop in the spinneret at a constant mass flow rate. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 43962.

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