Journal of Applied Polymer Science, Vol.83, No.10, 2157-2163, 2002
Improved spinnerette design for extrusion of polymeric large internal diameter hollow fiber membranes
Spinnerettes for extrusion of large (similar to 1 mm) internal diameter (i.d.) hollow fiber membranes must possess certain features to extrude fibers with the proper tensile and geometrical properties. Spinnerette designs that properly extrude small i.d. (< 200 mum) hollow fibers will produce large i.d. hollow fibers with low burst strengths because of poor flow patterns and insufficient time in the spinnerette to knit a strong seam interface. In this report, an alternative design is offered that provides much better fiber properties without creating high pressure drops or shear stresses at the spinnerette wall that would normally result in melt fracture. The equations that guide the presented spinnerette design are provided and the suggested design is successfully guided by the results. The new spinnerette design also has the feature of allowing rapid change of hollow fiber wall thickness by making the core fluid pin replaceable.