Spinneret design

Figure 3.33 Twin-orifice spinneret design used in solution-spinning of hollow fiber membranes. Polymer solution is forced through the outer orifice, while bore-forming fluid is forced through the inner capillary...

In an attempt to remove the problems associated with the acetone coagulation bath, fibers were air-gap spun into aqueous salt solutions, eg up to 25% of diammonium hydrogen phosphate or potassium phosphate or 5% zinc sulphate (109). This patent also makes it clear that the corrosive nature of the solution is an issue in spinneret design. 

The dried polyester polymer is transported to extruders where it is melted, and piunped to spinning packs held in a spin manifold. The spin packs contain spiimeiets with a large number of fine holes through which the melted polymer flows to form filaments. Any contaminants in the polymer are removed by filtration prior to the spinneret. Different spinneret designs enable a wide range of fibre cross-sections to be produced including solid round, hollow and trilobal. 

Spinneret design Coaxial spinneret Hollow or core-shell nanofibers... 

Figure 6.3 illustrates a spinneret design for preparing sheath-core conjugate fibre. One of the component streams is fed through a narrow tube while the second component stream supplying the sheath is fed around this... 

Effects of Spinneret Design and Flow Behavior within the Spinneret on Hoiiow-Fiber Membranes... 

Figure 31.9 illustrates the dual-layer spinneret design in our lab (Li et al., 2002). The outer-layer dope, inner-layer dope, and bore fluid are delivered to the orifice by passing through three independent channels. The most difficult parts of spinneret design arc precision and channel alignment. To run the dual-layer hollow-fiber spinneret, two metering pumps were employed to deliver inner and outer dopes. 

Zheng Y, Zeng Y (2014) Electric field analysis of spinneret design for multihole electrospinning system. J Mater Sci 49 1964-1972... 

A major disadvantage of these methods, is that due to the different spinneret design it is difiicult to replicate the solutions developed at research laboratories with needle-based electrospinning set-ups. Therefore major modifications in solution chemistry are required before an optimum solution and processing conditions can be achieved from lab to industrial scale. 

In the literature, different modifications of the spinneret design were proposed as follows (1) spinnerets with different flow angles, to tailor pore size distribution and control pure water permeability [46] and (2) spinnerets with microstructured annulus or needle, to increase the active surface area [47,48],... 

W. Nijdam, J. de Jong, C.J.M. van Rijn, T. Visser, L. Versteeg, G. Kapantaidakis, G.H. Koops, and M. Wessling, High performance microengineered hollow fiber membranes by smart spinneret design. Journal of Membrane Science 256 (2005) 209-215. 

N. Widjojo, T.S. Chung, D.Y. Arifin, M. Weber, and V. Warzelhan. (2010). The elimination of die swell and spinning instability in the hyperbranched polyethersulfone (HPES) hollow fiber spinning process via novel spinneret designs and precise spiiming conditions, Chem. Eng. J. 163 143-153. 

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