Question

The cross section of spinneret used for producing hollow fibre

• A. C-shaped
• B. Rectangular
• C. Annular concentric
• D. Triangular

Hint:

Hollow fibres are always produced using spinnerets that allow controlled internal void formation, typically annular in design.

Answer 1

The Correct Option is C

Step 1: Understanding hollow fibre production.
Hollow fibres require a continuous void at the centre of the fibre along its length. This is achieved by controlled polymer flow during extrusion.
Step 2: Role of spinneret geometry.
An annular concentric spinneret consists of two concentric openings—an outer ring for polymer flow and an inner core for creating the hollow region.
Step 3: Analysis of options.
C-shaped, rectangular, and triangular spinnerets produce special solid cross-sections but do not generate a central hollow channel.
Step 4: Conclusion.
Therefore, an annular concentric spinneret is used to produce hollow fibres.

Answer 2

Producing a hollow fibre means the extruded filament must have a continuous empty channel running down its centre, so the spinneret hole shape has to be one that can create that central void rather than just a shaped solid cross-section. Checking each shape against this requirement narrows it down.

1. C-shaped: A C-shaped orifice produces a solid filament with a non-round outline, but the opening is not closed around a central core, so it does not enclose a hollow channel down the fibre's length.
2. Rectangular: A rectangular orifice gives a flat, ribbon-like solid cross-section. Like the C-shape, there is no inner core being isolated from the outer polymer flow, so no hollow region forms.
3. Annular concentric: This design uses two concentric openings - polymer is extruded only through the outer ring, while the inner circular region is left empty, so a continuous hollow core runs through the fibre.
4. Triangular: A triangular orifice is used for trilobal fibres to create a solid, faceted cross-section, again without isolating any central void.

Only a spinneret with two concentric openings can keep the centre of the extruded filament empty while the polymer solidifies around it.

Therefore, the correct answer is Annular concentric.